Identification of tomato accessions as source of new genes for improving heat tolerance: from controlled experiments to field

Abstract

Background Due to global warming, the search for new sources for heat tolerance and the identification of genes involved in this process has become an important challenge as of today. The main objective of the current research was to verify whether the heat tolerance determined in controlled greenhouse experiments could be a good predictor of the agronomic performance in field cultivation under climatic high temperature stress. Results Tomato accessions were grown in greenhouse under three temperature regimes: control (T1), moderate (T2) and extreme heat stress (T3). Reproductive traits (flower and fruit number and fruit set) were used to define heat tolerance. In a first screening, heat tolerance was evaluated in 219 tomato accessions. A total of 51 accessions were identified as being potentially heat tolerant. Among those, 28 accessions, together with 10 accessions from Italy (7) and Bulgaria (3), selected for their heat tolerance in the field in parallel experiments, were re-evaluated at three temperature treatments. Sixteen tomato accessions showed a significant heat tolerance at T3, including five wild species, two traditional cultivars and four commercial varieties, one accession from Bulgaria and four from Italy. The 15 most promising accessions for heat tolerance were assayed in field trials in Italy and Bulgaria, confirming the good performance of most of them at high temperatures. Finally, a differential gene expression analysis in pre-anthesis (ovary) and post-anthesis (developing fruit) under heat stress among pairs of contrasting genotypes (tolerant and sensitive from traditional and modern groups) showed that the major differential responses were produced in post-anthesis fruit. The response of the sensitive genotypes included the induction of HSP genes, whereas the tolerant genotype response included the induction of genes involved in the regulation of hormones or enzymes such as abscisic acid and transferases. Conclusions The high temperature tolerance of fifteen tomato accessions observed in controlled greenhouse experiments were confirmed in agronomic field experiments providing new sources of heat tolerance that could be incorporated into breeding programs. A DEG analysis showed the complex response of tomato to heat and deciphered the different mechanisms activated in sensitive and tolerant tomato accessions under heat stress.

Assessing the heat sensitivity of Urdbean (Vigna mungo L. Hepper) genotypes involving physiological, reproductive and yield traits under field and controlled environment

“…Of all the growth stages, reproductive stage is the most sensitive stage affected by negative impact of heat stress (Zinn et al, 2010). High temperature stress causes anomalies and malfunction in reproductive processes ranging from reduction in pollen germination (PGP) percentage, pollen viability percentage (PVP), malformation in ovule to inhibition in fertilization process in various crops, including rice (Xu et al, 2021), wheat (Ullah et al, 2022), chickpea (Bhandari et al, 2020;Devi et al, 2022), common bean (Silva et al, 2019;Soltani et al, 2019) and tomato (Gonzalo et al, 2021). High PGP and PVP values are indicators of efficient reproductive function leading to high pod and seed setting resulting in improved yield under heat stress (Firon et al, 2006;Pham et al, 2020).…”

“…Studies conducted in controlled high temperature environment of growth chamber revealed PGP and PVP to be highly correlated with pods plant -1 and could be used as vital indicators of heat tolerance. Earlier studies have also indicated that these traits could be used for selecting heat tolerant genotypes in chickpea (Devi et al, 2022), common bean (Rainey and Griffiths, 2005), lentil (Sehgal et al, 2019) and tomato (Gonzalo et al, 2021).…”

Various tomato cultivars display contrasted morphological and molecular responses to a heat wave

“…For most tomato cultivars, if the temperatures exceed 26ºC during the day and 20ºC during the night, fruit set is impaired mainly due to floral development alteration, and therefore fruit yield is reduced (Sherzod et al ., 2020). Because the response to stress varies widely between genotypes (Arena et al ., 2020; Gonzalo et al ., 2021), gaining deeper knowledge of the developmental and molecular response of various cultivars may provide clues for innovative breeding strategies aiming at improving commercial tomato cultivars for better adaptability to climate change. In the present work, we investigated the responses to heat stress in eleven tomato cultivars producing fruits of different sizes and shapes.…”

Effect of Elevated Temperature on Tomato Post-Harvest Properties

“…We assessed the post-harvest properties of these 41 accessions, such as the duration of fruit shelf life and fungal susceptibility, under normal and high temperature regimes. These genotypes have been extensively characterised for their responses to elevated temperature and/or drought growth conditions using Qualitative Trait Loci analysis, high-throughput geno-and phenotyping, assessment of flowering, fruit set, yield, fruit nutritional composition, antioxidant and anti-inflammatory activities, as well as by screening for photosynthetic efficiency [23][24][25][26][27][28][29][30][31][32][33][34]. In addition, several candidate genes regulating heat stress tolerance were recently identified in varieties from this collection [24,29].…”