Asian J Agric & Biol. 2021(4). DOI: 10.35495/ajab.2021.02.097 AJAB Original Article Physiological changes associated with Okra mosaic virus infection in field grown okra plants Samuel Amiteye1,2, Andrew Sarkodie Appiah1*, Frederick Boateng2, Jacob Teye Kutufam1, Harry Mensah Amoatey2 1Biotechnology Centre, Biotechnology and Nuclear Agricultural Research Institute (BNARI), Accra, Ghana 2Department of Nuclear Agriculture and Radiation Processing, School of Nuclear and Allied Sciences, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana Received: February 23, 2021 Abstract Accepted: As a prerequisite for the breeding of virus-resistant okra cultivars, the effect of Okra May 27, 2021 mosaic virus infection on physiological performance of ten okra cultivars were assessed Online First: under field conditions within the coastal savannah agro-ecological zone of Ghana. All June 08, 2021 cultivars succumbed to the disease and expressed varying degrees of symptoms. The Published: September 21, 2021 results showed that plant height at initial and 50% flowering were significantly reduced with cultivar Clemson spineless showing the highest reduction of 38% and 35% respectively. Plant height at 50% podding was also reduced in all cultivars with the highest reduction (40%) occurring in cultivar Clemson spineless. Virus-infected plants of cultivars Kwabenya 1, Labadi dwarf and Asutem took on the average 43 days to attain 50% flowering compared to 25 days in healthy or control plants. Diseased plants had significantly (P<0.05) delayed, taking on the average 47 days after planting to attain 50% podding compared to the control plants with an average of 35 days. Infected plants of cultivars Kwabenya 1 and Labadi dwarf took the highest number of 51 days to attain 50% podding. Pod length and width were also reduced in all cultivars but were highest in cultivars Lucky 19 F1 and Clemson spineless at 52.19% and 46.25% respectively. Based on this assessment, cultivars Adom and Asutem which were less affected in terms of disease severity and fruit yield reduction could be exploited in future breeding programmes. Keywords: Okra, Plant growth, Okra mosaic virus, Virus resistant, Symptoms How to cite this: Amiteye S, Appiah AS, Boateng F, Kutufam JT and Amoatey HM, 2021. Physiological *Corresponding author email: changes associated with Okra mosaic virus infection in field grown okra plants. Asian andysark2000@gmail.com J. Agric. Biol. 2021(4): 202102097. DOI: https://doi.org/10.35495/ajab.2021.02.097 This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 License. (https://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction and nutritional content (Adetuyi et al., 2011). Okra is a robust crop, hence is able to survive harsh conditions Okra (Abelmoschus esculentus L. Moench) is grown where most other crops fail (Oppong-Sekyere et al, for its immature fruits and fresh tender leaves. These 2012). This unique agronomic quality coupled with its plant parts serve as food and an important source of rich nutritional qualities make it a very popular crop for raw materials for some pharmaceutical and other resource-poor small-holder farmers in rural areas industrial applications due to the high phytochemical across tropical Africa. A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 1/10 Samuel Amiteye et al Notwithstanding the importance of okra as a domestic order to be able to recommend the best cultivars for and export crop, its production is constrained by severe farmers in the short term and in the long term, those to crop damage and low yields due to viral diseases (Chen be incorporated into breeding programmes to expand et al., 2019; Asare-Bediako et al., 2014; Savary et al., the genetic variation of the crop. The present study, 2012), hence the full food, medicinal and economic therefore, sought to evaluate the effects of OkMV potentials of the crop are not realized. The most infection on ten okra cultivars in order to identify better important viruses of okra include Okra Yellow Vein performing cultivars. Mosaic Virus (OYVMV), Okra Mosaic Virus (OkMV) and Okra Leaf Curl Virus (OLCV). These viruses are Material and Methods widespread in tropical and subtropical regions across the world. OkMV has been reported as widespread in The study area Ghana, resulting in significant yield losses (Appiah et The research was conducted on the research fields of al., 2020). The virus is a member of Tymovirus group, the Biotechnology and Nuclear Agriculture Research characterised by a single stranded DNA (ssDNA) Institute (BNARI) of the Ghana Atomic Energy gonome and spread by the flea beetle Podagrica spp Commission (GAEC). The study area is located at (Asare-Bediako et al., 2014). Kwabenya, Accra on latitude 5º 40' N, longitude 0º 13' These important okra viruses infect okra plants either W with Ochrosol (Ferric Acrisol) soil type, derived singly or mixed. According to Hull (2002), mixed viral from quartzite Schist. The site is well drained and has infections could be either antagonistic or synergistic. an elevation of 76 m above sea level within the coastal Antagonism normally arises when co-infecting viruses savannah agro-ecological zone (Dickson and Benneh, are related resulting in cross protection (Aguero et al., 2004). The maximum and minimum average 2018) or interference (Kumar et al., 2016). Synergism temperatures for the period of study were 30.7 and 26.0 also arises when co-infecting viruses are not related, oC respectively with average annual rainfall of 220 resulting in more severe disease symptoms than those mm. The highest and lowest relative humidity were 75 caused by single infections (Cho et al., 2000). Studies and 60% respectively (Dickson and Benneh, 2004). done by Ndunguru and Rajabu (2004), revealed that okra exhibits a variety of symptoms which usually Planting materials and field design ranged from mild to severe, caused by either single or Planting materials used comprised five exotic okra mixed virus infections. In mild situations, okra show cultivars namely; Lucky 19F1 (LF1), F1 Kirene (FIK), symptoms such as veinal mottling, vein banding and F1 Sahari (F1S), Kirikou F1 (KF1) and Clemson leaf mosaic. In severe cases, however, infected plants Spineless (CS) obtained from Technisem, Accra and show small and twisted leaves, downward curling of five local okra cultivars comprising Asutem (AS), mature leaves, deformed fruits and stunted growth. Togo (TG), Labadi dwarf (LD), Kwabenya 1 (K1) and A large variety of okra cultivars exist in Ghana and are Adom (AD) obtained from the local markets and okra predominantly cultivated across the major okra- farmers’ fields. growing regions of the country (Ahiakpa et al., 2017). After land preparation and field demarcation, the okra These cultivars include exotic types sold by seeds were directly sown to a depth of 2 cm at a spacing commercial seed companies with several trade names. of 0.50 m x 0.60 m between and within rows in a Unfortunately, almost all known cultivars of okra Randomized Complete Block Design (RCBD) with currently cultivated in Ghana, both local and exotic are four replications. Each replicate measured 35 m x 7 m highly susceptible to the major viruses and many and were separated by 2 m from each other. Each block species of insect pests (Oppong-Sekyere et al, 2012; consisted of 10 subplots with each subplot measuring Prakasha et al., 2010; Petlamul et al., 2009). The 3 m x 3 m and spaced 1 m from one another. Four seeds implication of this is that production levels of okra per hill were sown and later thinned to one seedling have been generally very low. Although, some works after emergence. Cultural management practices such have already been done in Ghana, most of these studies as weed control and watering were done as and when have focused on viral disease epidemiology, little is required. known about the effects of viral diseases on growth and performance of different okra cultivars. Data collection There is, therefore, the need to evaluate the effects of Ten plants were randomly selected from the middle OkMV on cultivated okra cultivars present in Ghana in rows of each plot per cultivar and tagged. The ten A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 2/10 Samuel Amiteye et al selected plants consisted of five healthy or control 13, although this was not significantly different from plants and five infected plants. Symptom severity was the others. The least symptom severity score (2.0) at scored on the diseased plants following a five-point week was found in cultivar Adom and Asutem which scale (0 to 4) where; 0 = No symptom; 1 = Very mild recorded mild symptoms throughout the study period. symptoms, initial vein clearing, initial leaf yellowing, mild curling and blistering; 2 = Leaf completely yellow and inter-veinal regions remain green or yellow and blistering; 3 = Severe curling, yellowing, stunting and blistering; and 4 = Severe yellowing, curling, blistering and deformed pods (All leaves of the plants affected). Data was collected on quantitative traits with respect to reproductive and pod characters. The reproductive characters comprised Days to 50% flowering, Days to 50% podding, Plant height at initial flowering stage, Plant height at 50% flowering stage, and Plant height at 50% podding stage. Days to 50% flowering and Days to 50% podding were determined by counting the days Figure-1. Viral disease symptoms found on the okra after plant emergence. On the other hand, plant height at cultivars A: Healthy plant, B: mosaic, blistering and initial flowering stage, plant height at 50% flowering upward cupping of leaves, C: vein clearing, D: leaf stage, and plant height at 50% podding stage were malformation, E: mosaic and F: leaf yellowing, measured using tape measure and recorded in upward cupping of leaves and stunting. centimetres (cm). Chlorophyll contents of the cultivars were measured using hand-held SPAD meter. The pod Week 3 Week 5 week 7 week 9 week 11 week 13 characters that were recorded included pod length, pod 4.5 width and fresh fruit weight. The pod length and width 4 were taken with a tape measure and the mean for five 3.5 3 plants recorded. Fresh fruit weight was measured with a 2.5 spring balance and the mean recorded in kilogram (kg). 2 1.5 1 Statistical analysis 0.5 Genstat Statistical Software Package (12th edition), and 0 Microsoft Excel Software (2010 edition) were used for the data analyses and a p-value of 0.05 or less was Okra cultivars considered as statistically significant. The data Figure-2. Index of symptom severity for diseased collected on diseased and healthy plants were subjected plants of 10 okra cultivars. Bars represent the to Analysis of variance (ANOVA) and the Tukey’s standard error of means of four replications. pairwise comparison test was used to determine the differences among the means. Influence of OkMV on plant height at initial flowering stage Results OkMV infection influenced plant height at initial flowering stage. Generally, plant height was Viral disease symptom severity significantly (P<0.05) reduced in diseased plants of all Disease symptoms were found mostly in the young cultivars. The reduction in plant height was most severe leaves and included leaf yellowing, leaf malformation, in cultivars CS (38%), F1K (35%), AD (35%) and F1S vein clearing, mosaic, leaf blistering, upward cupping (24%) (Fig. 3). The overall percentage reduction in of leaves and stunting (Fig. 1). plant height of diseased plants compared to healthy Generally, symptom severity increased steadily from plants was 19.7%. week 3 to week 13 for all cultivars (Fig. 2). Cultivar Kwabenya 1 and Lucky19 F1 expressed the most severe symptoms of 3.85 and 3.61 respectively at week A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 3/10 Disease symptom severity Samuel Amiteye et al Plant height at 50% flowering stage was Days to 50% flowering as influenced by OkMV significantly as affected by OkMV infection infection Plant height at 50% flowering was significantly Generally, diseased plants took significantly longer (P<0.05) influenced by the effects of infection of time to start flowering irrespective of the cultivar (Fig. OkMV (Fig. 4). In all cultivars, at 50% flowering, plant 6). Diseased plants of cultivar K1, LD and AS took height was significantly (P<0.05) reduced in diseased averagely the highest number of days (43 days) to attain plants. The reduction in plant height was more 50% flowering. A second group comprising F1K, TG, pronounced in cultivars AD (24%), CS (35%), F1K F1S, CS, AD, KF1 and LF1 attained 50% flowering (28%) and F1S (26%) whilst KF1 had the lowest earlier at an average number of 38 days. On the other percentage reduction in plant height (13%). The overall hand, healthy plants of cultivars TG, F1S, F1K and AS percentage reduction in plant height of diseased plants took significantly the least number of days (25 days) to compared to the healthy ones was 20.4%. 50% flowering compared to the diseased ones. 25 Diseased Healthy 30 Diseased Healthy 25 20 20 15 15 10 10 5 5 AD AS CS F1K F1S K1 KF1 LD LF1 TG AD AS CS F1K F1S K1 KF1 LD LF1 TG Cultivar Cultivars Figure-3. Effect of OkMV infection on plant height Figure-5. Effect of infection of OkMV on plant at initial flowering stage. Bars represent the height at 50% podding stage. Bars represent standard error of means of four replications. the standard error of means of four replications. Diseased Healthy 25 Diseased Healthy 20 45 40 15 35 10 30 25 5 AD AS CS F1K F1S K1 KF1 LD LF1 TG 20 Cultivar 15 Figure-4. Effect of infection of OkMV on plant AD AS CS F1K F1S K1 KF1 LD LF1 TG height at 50% flowering stage. Bars represent the Cultivar standard error of means of four replications. Figure-6. Effects of infection of OkMV on days to 50% flowering. Bars represent the standard error Plant height at 50% podding stage was significantly of means of four replications. as influenced by infection of OkMV The effect of OkMV infection on plant height showed Days to 50% podding as influenced by by OkMV significant (P<0.05) differences when healthy and Infection diseased plants were compared at 50% podding (Fig. Days to 50% podding was delayed by the viral infection 5). Plant height reduction was more pronounced in the in all the okra cultivars. Infected plants had cultivar CS (40%) and least in KF1 (20%). The overall significantly (P<0.05) delayed (average 47 days after percentage decrease in height of diseased plants was planting) number of days to 50% podding compared to 14.9%. healthy plants with an average 35 days (Fig. 7). A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 4/10 Plant height (cm) Plant height (cm) Plant height (cm) Days to 50% flowering Samuel Amiteye et al Infected plants of cultivars K1 and LD took the highest healthy plants was 50% longer than pods of diseased number of days of at least 51 days to attain 50% plants. Similarly, in cultivars LF1, K1 and KF1, podding while cultivar F1K attained 50% podding average pod length decrease of 45%, 30% and 25% significantly earlier at 35 days. Healthy plants of F1K, respectively were estimated. Diseased plants of cultivar AS, LF1 and TG attained 50% podding earlier at AS produced significantly, the shortest pod lengths. average of 30 days after planting. However, when With respect to percentage reduction in pod length, infected, attainment of 50% podding was delayed for accession LF1 had the highest (52.19%) whereas F1S about 16 days except F1K which attained 50% podding had the lowest (26.44%) (Table1). at 36 days even when diseased. Table-1. Effects of infection of OkMV on pod length Diseased Healthy of okra 60 55 Pod length % Cultivar Sample 50 (mm) Reduction 45 Diseased 19.95±7.16cdefg 40 AD 29.38 35 Healthy 28.25±6.31 ab 30 Diseased 8.42±1.9 i 25 AS 34.82 Healthy 12.92±1.84 fgh 20 15 fgh AD AS CS F1K F1S K1 KF1 LD LF1 TG Diseased 12.30±1.35 CS 40.82 Cultivars Healthy 20.70±2.19bcde Figure-7. Effects of infection of OkMV on days to Diseased 15.12±3.25 efgh 50% podding. Bars represent standard error of F1K 38.90 Healthy 24.75±5.72 abcd four replications Diseased 16.55±5.42fgh F1S 26.44 Healthy 22.50±7.59 abcde Chlorophyll content as affected by infection of Diseased 17.30±6.60 cdefgh OkMV infection K1 42.92 Healthy 30.30±7.25 a Significantly (P<0.05) higher chlorophyll content was Diseased 15.95±7.24 defgh recorded in healthy plants of cultivar Clemson KF1 39.05 Healthy 26.17±10.88 abc spineless (one of the most affected cultivars) than in Diseased 12.57±1.51 fgh diseased plants. Chlorophyll content of healthy plants LD 28.45 Healthy 17.57±1.58cde increased from the third week after planting to the ninth Diseased 12.55±1.07fgh week while that of the diseased plants decreased (Fig. LF1 52.19 Healthy 26.25±6.77 ab 8). Diseased 10.82±1.23 gh TG 47.14 Healthy 20.47±7.83bcdef Each value is a mean of four replicates, and values followed by the same superscript(s) are not significantly different (p>0.05) according to Tukey’s pairwise comparison. Pod width as influenced by OkMV infection The effect of OkMV infection on pod width reduction was significant (P<0.05) (Table 2). Generally, all Figure-8. Effects of OkMV infection on the cultivars, local and exotic, healthy plants produced chlorophyll content of diseased plants of cultivar pods with bigger widths than pods produced from Clemson spineless. diseased plants. Healthy plants from F1K and AD produced significantly the biggest pod widths. On the Pod length as affected by OkMV infection other hand, diseased plants from TG, AS and CS In all cultivars, virus infection caused significant cultivars produced the least pod widths. Percentage (P<0.05) reduction in pod length. However, the effect reduction in pod length was observed to be most of the disease on pod length reduction was much pronounced in KF1 (35.22%) and least in AD (26.89) pronounced in TG where the average pod length of (Table 2). Diseased plants of cultivar AD and K1 A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 5/10 Days to 50% podding Samuel Amiteye et al produced significantly the highest pod widths of KF1, LF1 and TG. Highest percentage reduction in 9.65±1.17 and 8.80±0.90 respectively compared to fresh fruit weight was seen in cultivar LF1 (52.19%) diseased plants of other cultivars. whilst LD (28.45%) had the lowest. Table-2. Effect of OkMV on pod width of okra Table-3. Effects of infection of OkMV on fresh fruit % weight of okra Cultivar Sample Pod width (mm) Reduction Mean fresh % Cultivar Sample Diseased 9.65±1.17 cdefgh fruit weight (g) Reduction AD 26.89 Diseased 19.95±7.16fgh Healthy 13.20±1.15ab AD 29.38 Healthy 28.25±6.31 bc Diseased 5.87±1.05 i AS 27.79 Diseased 8.42±1.93 gh Healthy 8.13±0.84fgh AS 34.83 Healthy 12.92±1.84 def Diseased 6.25±0.52i CS 46.25 Diseased 12.30±1.35gh Healthy 11.63±1.25ab CS 40.57 Healthy 20.70±2.19 b Diseased 8.50±1.40 defghi F1K 39.59 Diseased 15.12±3.25 cde Healthy 14.07±3.17 a F1K 38.90 Healthy 24.75±5.72 a Diseased 8.42±2.52 efghi F1S 28.15 Diseased 16.55±5.42 h Healthy 11.72±3.25 abcd F1S 26.44 Healthy 22.50±7.59 efg Diseased 8.80±0.90 defghi fgh K1 30.15 Diseased 17.30±6.60 Healthy 12.60±1.58abc K1 42.90 Healthy 30.30±7.25 b Diseased 7.30±3.14hi Diseased 15.95±7.24 gh KF1 35.22 Healthy 11.27±3.44 abcdef KF1 39.05 Healthy 26.17±10.88 cde Diseased 7.55±1.43ghi Diseased 12.57±1.51 h LD 30.22 LD 28.45 Healthy 10.82±1.30 abcdef Healthy 17.57±1.58 bcd Diseased 8.05±0.25 fghi Diseased 12.55±1.07 gh LF1 36.11 LF1 52.19 Healthy 12.60±1.45 abc Healthy 26.25±6.77 bc Diseased 5.62±0.62i Diseased 10.82±1.23 gh TG TG Healthy 10.45±3.54bcdefgh 46.22 Healthy 20.47±7.83bcd 47.19 Each value is a mean of four replicates, and values Each value is a mean of four replicates, and values followed by the same superscript(s) are not followed by the same superscript(s) are not significantly different at (p>0.05) according to Tukey’s significantly different (p>0.05) according to Tukey’s pairwise comparison. pairwise comparison. Fresh pod weight as affected by OkMV infection Correlation among four essential traits in ten okra Fresh fruit weight was significantly (P<0.05) reduced cultivars by the effect of OkMV (Table 3). Generally, viral Correlation coefficients were worked out to study the infection caused an estimated 50% reduction in the relationship of chlorophyll content (CC) with fresh fruit fresh fruit weights comparing healthy and diseased weight (FFW), pod width (PW) and pod length (PL). plants. Cultivar F1K was found to produce the heaviest The results of correlation coefficients indicated that fresh fruit weights while diseased plants of F1S, LD chlorophyll content shared very strong positive and AS produced significantly the lightest fresh fruit correlation with fresh fruit weight (FFW) and pod weights. Cultivars that produced intermediate fresh width (PW) but weak negative correlation with pod fruit weights from diseased plants include AD, CS, K1, length. Fresh fruit weight (FFW) exhibited very weak A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 6/10 Samuel Amiteye et al correlation with pod length (PL) but very strong different cultivars in this study could be a result of the positive correlation with pod width (PW) while Pod differences in genetic make-up of the cultivars length (PL) and pod width (PW) shared very strong resulting in differential reactions to the virus. positive correlation. Reduction in the height of virus-infected plants have Table-4. Correlation among chlorophyll content, been reported in groundnuts (Appiah et al., 2016), fresh fruit weight, pod length and pod width cowpea (Kareem and Taiwo, 2007) and pepper CC FFW PL PW (Pazarlar et al., 2013). FFW 0.4067** Generally, flowering was delayed in diseased plants of all cultivars compared to healthy or control plants. 0.0002 Diseased plants took significantly longer time to PL -0.0787ns -0.0223ns flower irrespective of cultivar. Delay in flowering in 0.4936 0.8465 tomato plants infected with Potato virus X and PW 0.2268* 0.3460** 0.7862*** Tobacco mosaic virus (Balogun, 2003) and okra plants 0.0458 0.0019 0.0000 infected with OkMV (Ndunguru and Rajabu 2004) has been reported (Ndunguru and Rajabu, 2004). The CC = Chlorophyll content, FFW =Fresh fruit weight, delayed flowering observed in diseased cultivars in this PL = Pod length, PW = Pod width study could be due to impaired photosynthesis, ineffective uptake of nutrients, and other stress Below each correlation coefficient (bolded) is P -value conditions imposed by the disease during the growing (underlined). *, **, *** represent significant period of the cultivars (Niser et al., 2002). As in days correlation at P ≤ 0.05, 0.01, 0.001 respectively. ns = to 50% flowring podding was significantly affected by not significant at P ≤ 0.05. the viral infection in all the okra cultivars. The Discussion infection significantly delayed the number of days to 50% podding compared to healthy plants by an average It is noteworthy that the ten okra cultivars assessed in of 35 days. Viruses have a remarkable impact on their this study were previously evaluated for Okra mosaic host metabolism, with carbohydrate and chlorophyll disease resistance in which all cultivars succumbed to metabolism being two activities which are seriously the OkMV infection (Appiah et al., 2020). In the affected by viral infections. Chlorophyll content current study, symptom expression among the cultivars decreased in virus-infected plants of all the cultivars. was severe, perhaps due to cultivar susceptibility, Lower levels of chlorophyll observed in the virus- strain of the virus and probably the influence of other infected plants in this study may be due to inefficient viruses which were not detected in this study. The functioning of chlorophyllase, leading to poor infection resulted in different kinds of symptoms development of chloroplast or inhibition of chlorophyll which culminated in poor plant growth. The reduction synthesis as reported by Zhao et al., 2016 and Roca and in plant growth and yield as a result of virus infection Minguez-Mosquera (2003). Furthermore, the chlorotic has been reported (Chen et al., 2019; Latham et al., and mosaic symptoms observed on the virus-infected 2004). plants could indicate the occurrence of chloroplast- Generally, plant height at initial flowering stage, 50% virus interactions (Zhao et al., 2016; Rahoutei et al., flowering and 50% podding stages was significantly 2001), resulting in fluctuation of chlorophyll reduced in diseased plants of all cultivars. The average fluorescence and reduced chlorophyll pigmentation percentage reduction in plant height of diseased plants (Liu et al., 2014). The reduction in the chlorophyll compared to healthy plants at initial flowering stage content may have resulted in reduced photosynthetic was 19.7%. This result corroborates the findings of activity culminating in low yields. Parimala et al. Ndunguru and Rajabu (2004) who recorded 19.5% (2009) reported a decrease in yield of virus-infected reduction in plant height between virus-infected and okra as a result of reduced chlorophyll content. In this healthy plants. In most of the cases, stunting was study, chlorophyll content showed a strong positive severe, probably due to mixed infections with other correlation with fresh fruit weight. There has been a viruses. Cho et al. (2000), observed severe plant growing interest on the part of plant breeders to damage as a result of infection caused by two or more develop higher yielding varieties of crops (Nestel et al., viruses. However, it must be noted that the disparity in 2006; Gregorio, 2002). Therefore, information on the the percentage reduction in plant height observed in the association between the chlorophyll content and yield A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 7/10 Samuel Amiteye et al parameters will serve as a useful guide in future variability which could be exploited in breeding breeding efforts. Results from the correlation analysis programmes. Singh et al. (2017), observed significant implies that targeting high chlorophyll content of okra variation among okra cultivars, suggesting variations leaves through breeding will consequently lead to that are useful for studying genetic diversity of okra improvement in fresh fruit weight and pod width. germplasm. Cultivars K1, AD and F1K are the best Significant reduction in pod length, width and weight with respect to pod length, pod width and fresh fruit was observed in virus-infected plants of all the weight and therefore can be selected as parents in future cultivars. Generally, for all cultivars; local or exotic, breeding work. healthy or control plants produced pods with bigger widths than pods produced from diseased plants. It is Conclusion noteworthy that despite the infection, diseased plants of cultivar AD and K1 produced significantly higher This study has elucidated the effect of okra mosaic pod widths than diseased plants of other cultivars. This disease on the growth and performance of ten okra may suggest that these cultivars are tolerant to viral cultivars under field conditions within the coastal infections and therefore may offer some bases for their savannah agro-ecological zone of Ghana. All ten okra selection for introgression of desirable genes for high cultivars succumbed to the disease but had varying fruit yield into preferred cultivars. Tolerance of okra levels of reduction in growth and performance. cultivars to OYVMV have been reported (Mohsan et Diseased plants compared to healthy ones had al., 2017). OkMV infection reduced fresh fruit weight significantly reduced (p≤0.05) chlorophyll content, of all cultivars. The viral infection resulted in an plant height, delayed flowering process and fresh pod estimated 50% reduction in the fresh fruit weights weight. Lower levels of chlorophyll content were compared to weights recorded in healthy plants. The observed in the virus-infected plants with consequent reduction in the fruit weight of the virus-infected okra reduction in photosynthetic activity culminating in cultivars observed in this study could be due to lower yields. Plant height of diseased plants was reduction in photosynthesis (Liu et al., 2014) resulting significantly reduced compared to healthy or control from the viral infection. Differences in the average plants at initial flowering stage. The viral infection also fresh pod weight per plant observed among the significantly delayed the achievement of 50% podding cultivars may be attributed to inherent fruit by an average of 35 days. Similarly, fresh fruit weights characteristics such as higher pod diameter, higher of diseased plants decreased by an estimated 50% number of pods per plant, fruit length, and higher compared to weights recorded in healthy plants. The number of branches per plant (Mahapatra et al., 2007; observed significant reduction in the yield parameters Mohammad et al, 2001 and Singh and Jain, 2002). caused by OkMV disease emphasises the damaging Pod length, pod width and fresh fruit weight are potential of the disease on okra cultivation and the need desirable characteristics for domestic, industrial and for improved control measures to maximise commercial preference (Alam and Hossain, 2008). production. Two local cultivars, Adom and Asutem Results from the current study indicate that pod length, were found to be the best performing cultivars under pod width and fresh fruit weight were considerably field conditions having recorded less reduction in fresh decreased in diseased plants compared to records of fruit weight despite the infection. Therefore, these these characters in the healthy or control plants. cultivars can be selected as locally-adapted, good Furthermore, reports by Echezona and Offordile materials tolerant to OkMV for further improvement in (2011) attributed the cause to the feeding activity of future breeding work. Podagrica spp. that causes damage to the leaves resulting in significant reduction in the photosynthetic Acknowledgement capacity. Similar reduction in the yield of okra cultivars as a result of OkMV infection has been We wish to profoundly commend the invaluable reported (Fajinmi and Fajinmi, 2010). contributions of Mr. Yusif Mohammed as well as staff In addition to the effect of OkMV on growth and of the Biotechnology Centre that have enabled the performance of the okra cultivars, the result of this success of this work. We also acknowledge the study has also revealed significant variation among Biotechnology and Nuclear Agriculture Research cultivars with respect to pod length, pod width and Institute (BNARI) of the Ghana Atomic Energy fresh fruit weight. This implies a broad range of genetic Commission (GAEC) for permitting the use of the A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 8/10 Samuel Amiteye et al Molecular Biology Laboratory and other facilities to tomato seedlings singly or doubly infected with carry out this study. Potato X potexvirus and Tobacco mosaic tobamovirus. Biokemistri 14: 64-74. Disclaimer: None. Chen S, Wellin L and Guohui Z, 2019. Symptoms and Conflict of Interest: None. yield loss caused by rice stripe mosaic virus. Virol. Source of Funding: None. J. 16(145). DOI: https://doi.org/10.1186/s12985- 019-1240-7 References Cho JD, Kim JS, Choi HS, La YJ and Kim KS, 2000. Ultrastructural aspects of the mix infections of Aguero J, Gomez-Aix C, Sempere RN, Garcia-Villalba watermelon mosaic potyvirus isolated from R, Garcia-Nunez J, Hernando Y and Aranda MA, pumpkin and cucumber green mottle mosaic 2018. Stable and broad spectrum cross-protection tobamovirus from watermelon. Plant Pathol. 16: against Pepino Mosaic Virus attained by mixed 216-221. infection. Front. Plant Sci. 9: 1810. doi https://doi.org/10.3389/fpls.2018.01810. Dickson KB and Benneh G, 2004. A new geography of Ahiakpa, J. K. Magdy, M., Werner. O., Amoatey, H. Ghana. Longmans Group Limited, London, UK. M., Yeboah, M. A., Appiah A. S., Quartey, Echezona BL and Offordile JI, 2011. Responses of flea E. K, Ros, R. M. (2017). Intra-specific variation in beetles (Podagrica spp.) and okra plants West African and Asian germplasm of (Abelmoschus esculentus L. Moench) to okra (Abelmoschus spp. L.). Annals of differently coloured polyethylene shades. Int. J. Agricultural Science 62:131– 138. Pest Manage. 57(2): 161-168. Akaho EKH, Maakuu BT, Anim-Sampong S, Emi- Fajinmi AA and Fajinmi OB, 2010. Incidence of okra Reynolds G, Boadu HO, Osae EK, Akoto-Bamford mosaic virus at different growth stages of okra S, Dodoo-Amoo DNA, 2003. Intermediate safety plants ([Abelmoschus esculentus (L.)] Moench) analysis report (GAEC- under tropical condition. J. Gen. Mol. Virol. 2(1): NNRI- RT-90). 28-31. Alam A and Hossain MM, 2008. Variability of Gregorio GB, 2002. Progress in plant breeding for different growth contributing parameters of some trace minerals in staple crops. J Nutr. 132: 500 – okra (Abelmoschus esculentus L.) accessions and 502. their interrelation effects on yield. J. Agric. Hull R, 2002. Matthew's plant Virology 4th edition. Rural Devel. 6: 25-35. Academic Press, San Diego, California, USA. Appiah AS, Amiteye S, Boateng F and Amoatey HM, Kareem KT and Taiwo MA, 2007. Interactions of 2020. Evaluation of okra (Abelmoschus esculentus viruses in Cowpea: effects on growth and yield L. Moench) cultivars for resistance to Okra mosaic parameters. Virol. J. 4: 15. DOI:10.1186/1743- virus and Okra yellow vein mosaic virus. 422X-4-15 Australas. Plant Pathol. 49(11): Kumar N, Barua S, Riyesh T, Chaubey KK, Rawat KD, DOI:10.1007/s13313-020-00727-3 Khandelwal N, Mishra AK, Sharma N, Chandel Appiah AS, Offei SK, Tegg RS and Wilson CR, 2016. SS, Sharma S, Singh MK, Sharma DK, Singh SV Varietal response to groundnut rosette disease and and Tripathi BN, 2016. Complexities in isolation the first report of Groundnut ringspot virus in and purification of multiple viruses from Ghana. Plant Dis. 100: 946-952. mixed viral infections: viral interference, Asare-Bediako E, Addo-Quaye A and Bi-Kusi A, persistence and exclusion. PLoS One 11: 2014. Comparative efficacy of plant extracts in e0156110. managing whitefly (Bemisia tabaci Gen) and leaf Latham LJ, Jones RAC and Coutts BA, 2004. Yield curl disease in okra (Abelmoschus esculentus losses caused by virus infection in four L). Am. J. Agric. Sci. Technol. 2(1): 31-41. combinations of non-persistently aphid- Adetuyi FO, Osagie AU and Adekunle AT, 2011. transmitted virus and cool-season crop legume. Nutrient, anti-nutrient, mineral and zinc Austr. J. Exp. Agric. 44(1). Ea03060. bioavailability of okra Abelmoschus esculentus (L) Liu J, Yang J, Bi H and Zhang P, 2014. Why mosaic? Moench Variety. Am. J. Food Nutr. 1(2): 49-54. Gene expression profiling of African cassava Balogun OS, 2003. Patterns of disease manifestation in mosaic virus-infected cassava reveals the effect of A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 9/10 Samuel Amiteye et al chlorophyll degradation on symptom Univ. J. 12: 43-49. development. J. Integr. Plant Biol. 56: 122-132. Prakasha TL, Patil MS and Benagi VI, 2010. Survey Mahapatra MR, Acharyya P and Sengupta S, 2007. for bhendi yellow vein mosaic disease in parts of Variability and association analysis in okra. Indian Karnataka. Karnataka J. Agric. Sci. 23: 658-659. Agric. 51: 17-26. Rahoutei J, García-Luque I and Barón M, 2001. Mohammad A, Muhammad SM and Mushtaq Y, 2001. Inhibition of photosynthesis by viral infection: Comparative study on the performance of some effect on PSII structure and function. Physiol. exotic okra. Int. J. Agric. Biol. 3: 423-425. Plant. 110: 286–292. 10.1034/j.1399- Mohsan M, Saeed S and Qamar S, 2017. Varietal 3054.2000.110220. reaction of different okra cultivars against Okra Roca M and Minguez-Mosquera MI, 2003. yellow vein mosaic virus under field condition. Involvement of chlorophyllase in chlorophyll Adv. Res. J. Multidisc. Discov. 10(4): 18-21. metabolism in olive varieties with high and low Ndunguru J and Rajabu AC, 2004. Effect of okra chlorophyll content. Physiol. Plant. 117: 459–66. mosaic virus disease on the above-ground Savary S, Ficke A, Aubertot J-N and Hollier C, 2012. morphological yield components of okra in Crop losses due to diseases and their implications Tanzania. Sci. Hortic. 99: 225-235. for global food production lossess and food Nestel P, Bouis HE, Meenakshi JV and Pfeiffer W, security. Food Security. 4(4): DOI: 2006. Biofortification of staple food crops. J. 10.1007/s12571-012-0200-5 Nutr. 136: 1064-1067. Singh DK and Jain SK, 2002. Performance of okra Niser N, Irfan M, Khan J, Nabi G, Muhammed I and cultivars. Annual Research Report. Submitted to Badshah N, 2002. Influence of various DES. Pantnager. pp. 3-5. levels of nitrogen and phosphorus on the Singh N, Singh DK, Sati UC, Rawat M and Pandey P, growth and yield of Chilli. Asian J. Plant 2017. Genetic analysis studies in okra Sci. 1(5): 599-601. [Abelmoschus esculentus (L.) Moench]. Int. J. Pure Oppong-Sekyere D, Akromah R, Nyamah EY, Brenya Appl. Biosci. 5: 361-367. E and Yeboah S, 2012. Evaluation of some okra Zhao J, Zhang X, Hong Y and Liu Y, 2016. Chloroplast (Abelmoschus spp L.) germplasm in Ghana. Afr. J. in plant-virus interaction. Front. Microbiol. 7: Plant Sci. 6(5): 166-178. 1565. Parimala P, Prabhu IM and Muthuchelian K, 2009. Contribution of Authors Physiological response of yellow vein mosaic virus-infected bhendi [Abelmoschus esculentus] leaves. Physiol. Mol. Plant Pathol. 74: 129–133. Amiteye S, Appiah AS and Boateng F: Pazarlar S, Gumus M and Oztekin GB, 2013. The Contributed to the conceptualization of the study, Effects of Tobacco mosaic virus Infection on experimental design, data analysis and Growth and Physiological Parameters in Some interpretation, article review and final approval of Pepper Varieties (Capsicum annuum L.) Notulae manuscript. Botanicae Horti Agrobotanici Cluj-Napoca, 41(2), Kutufam JT: Contributed to research design, data 427-433. https://doi.org/10.15835/nbha4129008 collection and final reading of the manuscript. Petlamul W, Ngampongsai A and Petcharat J, 2009. Amoatey HM: Contributed to the Oviposition preference of papaya fruit fly, conceptualization of the study, manuscript Bactrocera papayae Drewand Hancock (Diptera: critiquing and final approval of the manuscript. Tephritidae) on some chili varieties. Thaksin A s i a n J A g r i c & B i o l . 2 0 2 1 ( 4). 10/10