Cappetta, Elisa (2020) Selection of superior heat tolerant tomato lines through genetic and genomic strategies. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Selection of superior heat tolerant tomato lines through genetic and genomic strategies
Date: 13 March 2020
Number of Pages: 122
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Dottorato: Scienze agrarie e agroalimentari
Ciclo di dottorato: 32
Coordinatore del Corso di dottorato:
Ercolano, Maria RaffaellaUNSPECIFIED
Date: 13 March 2020
Number of Pages: 122
Keywords: heat stress, genotyping, phenotyping
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/07 - Genetica agraria
Date Deposited: 20 Mar 2020 15:33
Last Modified: 05 Nov 2021 14:01

Collection description

Climate is unequivocally changing. The planet's average surface temperature has risen about 1.62 degrees Fahrenheit (0.9 degrees Celsius) since the late 19th century. Most of the warming climates occurred in the past 35 years, were recorded in the last 10 years. Global warming affects agriculture in a number of ways, including temperate region average temperature changes and climate extremes. Tomato (Solanum lycopersicum) is both an important commercial crop and a model system for genetic studies, due to its diploid, relatively compact, and recently sequenced genome and to the availability of large genetic and genomic resource collections. Tomato species is highly sensitive to high temperature and few degrees above its optimum growth temperature threshold can lead to serious deleterious effects, such as flower abscission, decrease of pollen quality, abnormal growth, reduced fruit set and yield. Therefore, the development of innovative strategies to obtain tomato cultivars with improved yield under high temperature conditions is a main goal for plant molecular science and breeding. In this thesis, different breeding strategies were used to improve tomato cultivars tolerance to heat stress. A F4 segregating population, deriving from the tomato variety JAG8810, previously selected for yield performance under hot stress, was phenotypically investigated under heat stress conditions to evaluate quantitative and qualitative traits. By the means of a PCA analysis, best and worst performers were selected. Extreme individuals for yield were also evaluated for sub-traits, such as pollen viability, to better investigate the basis of heat stress tolerance and correlations among heat tolerance component traits. In addition, the cultivar Moneymaker was tested for a heat treatment on limited areas, suggesting that heat stress response is a local process. The F4 population deriving from the JAG8810 variety, was sequenced by genotyping by sequencing (GBS) approach to identify all possible variants. Genomic prediction models for yield production per plant (YP) and soluble solid content (SSC) under heat stress, were developed. Several parameters, including training population size and composition and marker quality were adjusted to obtain optimized models for assessed traits and population. The predicted GEBVs (genetic breeding values) of F5 offspring were phenotypically validated in field. Furthermore, the most meaningful SNPs selected for model construction were used to conduct a QTL analysis to shed light on the genetic basis of heat tolerant traits in tomato. The analysis permitted the identification of 5 QTLs involved in yield and one in SSC. Two candidate genes putatively involved in heat stress tolerance were discovered in regions underlining QTLs. Finally, with the aim to identify regulatory elements involved in the abiotic stress tolerance, a tomato genome scan and a phylogenetic analysis of Dof proteins was performed identifying SlDof11 as suitable target for CRISPR/Cas9 experiments.


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