Accelerating the Development of Heat Tolerant Tomato Hybrids through a Multi-Traits Evaluation of Parental Lines Combining Phenotypic and Genotypic Analysis

Abstract

The constitution of heat tolerant F1 hybrids is a challenge to ensure high yield and good fruit quality in the global climate. In the present work, we evaluated 15 genotypes for yield-related traits highly affected by high temperatures (HT). This phenotypic analysis allowed to identify four parental genotypes showing promising yield performances under HT conditions. Two of these genotypes also exhibited good fruit quality traits. A molecular marker analysis was carried out for six resistance genes to pathogens mostly affecting tomatoes. This analysis evidenced the presence of a maximum of three resistant alleles in parental genotypes. Exploring single nucleotide polymorphisms (SNPs) revealed by two high-throughput genotyping platforms allowed identifying additional 12 genes potentially involved in resistance to biotic stress, to be further investigated. Following these considerations, 13 F1 hybrids were constituted combining the parental genotypes and then evaluated for multiple traits under HT conditions. By estimating a hybrid index based on yield performances, desirable quality and resistance gene, we identified seven hybrids showing the best performances. The promising results obtained in the present work should be confirmed by evaluating the best hybrids selected for additional years and environments before proposing them as novel commercial hybrids that could maintain high performances under HT conditions.

Genomic Insights into the Origin of a Thermotolerant Tomato Line and Identification of Candidate Genes for Heat Stress

“…Results showed that during the summer season, when temperatures were recorded to exceeded 32 °C with peaks of 38 °C, one genotype, named E42, exhibited a high and stable yield production (2.93 kg/plant) comparable to those of the tomato hybrids DOCET (3.13 kg/plant) and JAG8810 (3.37 kg/plant), reported to be heat-tolerant (Monsanto, unpublished results). Particularly, E42 stands out for the high number of total flowers and total number of fruits in all environments (open field, under tunnel), even when grown with one-month late transplant to increase exposure to high temperatures during reproduction [ 11 , 12 , 13 ]. These data were also confirmed by using a selection index based on fruit set, total number of fruits and yield production (both by Olivieri et al [ 13 ] and Ruggieri et al [ 12 ]), where the good performances of E42 were compared with 14 and 45 tomato lines, respectively.…”

“…Particularly, E42 stands out for the high number of total flowers and total number of fruits in all environments (open field, under tunnel), even when grown with one-month late transplant to increase exposure to high temperatures during reproduction [ 11 , 12 , 13 ]. These data were also confirmed by using a selection index based on fruit set, total number of fruits and yield production (both by Olivieri et al [ 13 ] and Ruggieri et al [ 12 ]), where the good performances of E42 were compared with 14 and 45 tomato lines, respectively. Francesca et al [ 14 ] compared physiological traits of E42 and the thermotolerant LA3120 (Malintka) genotype (Tomato Genetics Resource Center, TGRC, University of California, Davis, CA, USA) under heat stress.…”

“…Data obtained using a genotyping by sequencing (GBS) strategy [ 11 , 13 ] evidenced a high genetic variability of E42 respect to other analyzed genotypes. Since this strategy is based on reduced representation sequencing (RRS) approaches through the use of restriction enzymes [ 15 , 16 ], its major limitation is due to the random distribution of restriction enzyme sites on the genome, and thus the inability to target polymorphisms localized within genes or having a functional significance [ 17 ].…”

Tomato F3 lines development and its selection index based on narrow-sense heritability and factor analysis

“…The index selection approach is an effective approach in multicharacter-based selection. The effectiveness of this approach has been reported by Authrapun et al (2021), Olivieri et al (2021), andFarid et al (2021). Basically, index selection uses index values from a combination of several selection criteria with specific weighting values (Wang and Chen 2016).…”

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

“…Analyses of reproductive thermotolerance has been carried out in several tomato genotypes, including cultivars [ 11 , 29 , 30 , 31 , 32 , 33 ], breeding lines [ 19 , 32 , 34 ] and wild relatives [ 7 , 35 ]. Up to date, few studies have addressed the response to heat in tomato landraces [ 36 , 37 ], those cultivated populations adapted to specific climatic and agronomic conditions and preserved by farmers [ 38 ].…”