Dynamics of Fertility-Related Traits in Tomato Landraces under Mild and Severe Heat Stress

Abstract

Studies on the reproductive dynamics under heat stress are crucial to breed more tolerant cultivars. In tomato, cultivars, breeding lines, and wild species have been evaluated for their response to heat stress. Here, we addressed the study to a panel of selected landraces representing traditional genotypes that usually show high adaptation to local environments. In two experiments, spaced by 12 years, we set-up an identical experimental design with plants transplanted at two different dates to expose the second field to thermic stress with natural fluctuations. Such a strategy resulted in both a mild and severe stress in the two years. The landraces showed wide variation for both vegetative and reproductive traits; all traits were affected by heat, mostly with a significant Genotype*Environment interaction. A high broad-sense heritability was estimated for plant height, stigma position, pollen viability, and fruit weight. Low heritability estimates were found for the number of flowers, fruit set, and yield. Despite the interaction, traits recorded under control and heat conditions were positively correlated. Multivariate analysis located the genotypes in a topography that was stable under all conditions, except under the harshest temperatures. The study revealed that landraces present a wide variability for the response of reproductive traits to thermic challenges and that such a variation could be useful to dissect the traits with higher heritability and identify quantitative trait loci for breeding more resilient varieties.

Phenotypic and Genotypic Diversity of the Tomato Germplasm From the Lazio Region in Central Italy, With a Focus on Landrace Distinctiveness

“…Notwithstanding, landraces have few chances to outstand modern hybrids and be adopted in intensive vegetable productions for large market targets, and it is acknowledged that they represent an important genetic material to be preserved and valorized, to satisfy the needing and perspective of niche agriculture and markets, that appreciate traditional products for their quality (Baldina et al, 2016;Casañas et al, 2017). In addition, landraces may be used as the gene donors for breeding novel varieties for the forthcoming needs, which included those imposed by climatic changes (Farinon et al, 2022).…”