Abstract
Among the abiotic stresses affecting plant reproduction, high temperature is one of the most prominent ones because it directly affects fruit set. So far, little attention has been paid to the investigation of the variation in high temperature tolerance among wild tomato (Solanum lycopersicum) germplasm. The objective of this study was to determine the tolerance of 17 different cultivated and wild tomato accessions to high temperature, using a pollen viability screening approach. Each of the 17 genotypes of tomato was analysed for their pollen quality under a 32 °C (day)/26 °C (night) regime. The total number of pollen per flower and the fraction of viable pollen were recorded. The number of pollen per flower varied between 35,547 and 109,490 whereas the fraction of viable pollen varied between 0.03 and 0.71. No correlation was found between these two traits. However, the combination of these traits could provide the best reproductive capability under high temperature. In this study, thermo-tolerant (LA2854, LA1478 and LA0417) as well as thermo-sensitive (LA1719, LA1580, and SWEET4) genotypes have been identified. Those genotypes can be used as novel genetic resources to get more insight into pollen thermo-tolerance mechanisms and be included in breeding programs.
Highlights
High temperature is one of the major abiotic stresses affecting plant reproduction, and fruit set (Dane et al 1991)
S. pimpinellifolium accessions: LA0417, LA1478, LA1719, LA1580, LA1584 and LA2854 were obtained from the Tomato Genetics Resource Centre (TGRC)
Wild tomato germplasm has been successfully used in breeding programs to introduce different traits, such as various disease resistance genes, into cultivated tomato (Labate and Robertson 2012)
Summary
High temperature is one of the major abiotic stresses affecting plant reproduction, and fruit set (Dane et al 1991). Most commercial tomato (Solanum lycopersicum) genotypes are not tolerant to high temperatures. A rise of a few degrees above the optimum growing temperature will, lead to a decrease of fruit set. Optimum growing temperatures for tomato are between 18 and 25 °C (Hurd and Cooper 1970). Developing tomato genotypes tolerant to high temperature may be a valuable strategy to cope with these environmental changes. Tolerance to high temperature is not an easy trait to improve due to its low heritability (Hanson et al 2002; Hazra et al 2009), possibly due to its sensitivity to other environmental factors such as humidity
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