An overview of heat stress in tomato (Solanum lycopersicum L.)

Abstract

Heat stress has been defined as the rise of temperature for a period of time higher than a threshold level, thereby permanently affecting the plant growth and development. Day or night temperature is considered as the major limiting factor for plant growth. Earlier studies reported that night temperature is an important factor in the heat reaction of the plants. Tomato cultivars capable of setting viable fruits under night temperatures above 21 °C are considered as heat-tolerant cultivars. The development of breeding objectives is generally summarized in four points: (a) cultivars with higher yield, (b) disease resistant varieties in the 1970s, (c) long shelf-life in 1980s, and (d) nutritive and taste quality during 1990s. Some unique varieties like the dwarf “Micro-Tom”, and the first transgenic tomato (FlavrSavr) were developed through breeding; they were distributed late in the 1980s. High temperature significantly affects seed, pollen viability and root expansion. Researchers have employed different parameters to evaluate the tolerance to heat stress, including membrane thermo stability, floral characteristics (Stigma exertion and antheridia cone splitting), flower number, and fruit yield per plant. Reports on pollen viability and fruit set/plant under heat stress by comparing the pollen growth and tube development in heat-treated and non-heat-stressed conditions are available in literature. The electrical conductivity (EC) have been used to evaluate the tolerance of some tomato cultivars in vitro under heat stress conditions as an indication of cell damage due to electrolyte leakage; they classified the cultivars into three groups: (a) heat tolerant, (b) moderately heat tolerant, and (c) heat sensitive. It is important to determine the range in genetic diversity for heat tolerance in tomatoes. Heat stress experiments under field conditions offer breeders information to identify the potentially heat tolerant germplasm.

Functional Characterization of Tomato Phytochrome A and B1B2 Mutants in Response to Heat Stress

“…However, phyB1B2 produced fertile pollen for a longer time under HS, followed by phyA, in comparison with WT pollen, which quickly reacted to high temperatures (Figure 7). Stigma exertion and antheridia cone splitting are floral characteristics used to evaluate HS tolerance [45]. PhyA achieved a significantly lower percentage of stigma-exerted and abnormal flowers compared to WT within 2 weeks under fluctuating high temperature; at the same time, no marked difference occurred when compared to phyB1B2 (Figure 4C, D).…”

“…High Tm causes undesirable defects in tomato flowers. There are indicated parameters related to floral characteristics that are used to evaluate tomato tolerance to HS in the flowering stage, such as stigma exertion, antheridia cone splitting, and flower number [45]. HS induced stigma exertion and antheridia cone splitting [46,47].…”

Metabolic changes associated with chilling injury tolerance in tomato fruit with hot water pretreatment

“…The highest level of sucrose agreed with the results of Iwahashi and Hosoda (2000) who reported a lower accumulation of invertase protein in tomato fruit after the application of thermal treatment. Furthermore, sucrose availability has been related to the heat stress tolerance of tomato fruit (Almeida et al, 2020;Alsamir et al, 2021).…”

Effect of Elevated Temperature on Tomato Post-Harvest Properties

“…Heat tolerance is particularly influenced by the plant's genotype and management practices. Crops like tomato are specifically sensitive to heat stress during the reproductive phase, causing flower abortion and limited fruit set, and thereby leading to substantial yield loss [3][4][5]. Heat stress can also affect fruit quality of tomatoes by altering physical properties such as size and colour, nutritional composition and sensorial attributes.…”