Genomic and Phenotypic Diversity of Cultivated and Wild Tomatoes with Varying Levels of Heat Tolerance
Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Assessment of genetic variability in heat-tolerant tomato germplasm is a pre-requisite
to improve yield and fruit quality under heat stress. We assessed the population structure and
diversity in a panel of three Solanum pimpinellifolium (wild tomatoes) and 42 S. lycopersicum (cultivated
tomatoes) lines and accessions with varying heat tolerance levels. The DArTseq marker was used for
the sequencing and 5270 informative single nucleotide polymorphism (SNP) markers were retained
for the genomic analysis. The germplasm was evaluated under two heat stress environments for
five yield and flower related traits. The phenotypic evaluation revealed moderate broad-sense
heritabilities for fruit weight per plant and high broad-sense heritabilities for fruit weight, number
of inflorescences per plant, and number of flowers per inflorescence. The hierarchical clustering
based on identity by state dissimilarity matrix and UPGMA grouped the germplasm into three
clusters. The cluster analysis based on heat-tolerance traits separated the germplasm collection into
five clusters. The correlation between the phenotypic and genomic-based distance matrices was
low (r = 0.2, p < 0.05). The joint phenotypic and genomic-based clustering grouped the germplasm
collection into five clusters well defined for their response to heat stress ranging from highly sensitive
to highly tolerant groups. The heat-sensitive and heat-tolerant clusters of S. lycopersicum lines were
differentiated by a specific pattern of minor allele frequency distribution on chromosome 11. The
joint phenotypic and genomic analysis revealed important diversity within the germplasm collection.
This study provides the basis for efficient selection of parental lines to breed heat-tolerant varieties.
Description
Research Article
Keywords
genetic variability, heat tolerance, heritability, SNP markers, tomatoes