Genetic and Molecular Mechanisms Conferring Heat Stress Tolerance in Tomato Plants

Abstract

Climate change is a major threat to global food security. Changes in climate can directly impact food systems by reducing the production and genetic diversity of crops and their wild relatives, thereby restricting future options for breeding improved varieties and reducing the ability to adapt crops to future challenges. The global surface temperature is predicted to rise by an average of 0.3°C during the next decade, and the Paris Agreement (Paris Climate Accords) aims to limit global warming to below an average of 2°C, preferably to 1.5°C compared to pre-industrial levels. Even if the goal of the Paris Agreement can be met, the predicted rise in temperatures will increase the likelihood of extreme weather events, including heatwaves, making heat stress (HS) a major global abiotic stress factor for many crops. HS can have adverse effects on plant morphology, physiology, and biochemistry during all stages of vegetative and reproductive development. In fruiting vegetables, even moderate HS reduces fruit set and yields, and high temperatures may result in poor fruit quality. In this review, we emphasize the effects of abiotic stress, especially at high temperatures, on crop plants, such as tomatoes, touching upon key processes determining plant growth and yield. Specifically, we investigated the molecular mechanisms involved in HS tolerance and the challenges of developing heat-tolerant tomato varieties. Finally, we discuss a strategy for effectively improving the heat tolerance of vegetable crops.

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

“…These data suggest that a favorable SP can be harnessed by breeding, although few QTLs for this trait are known. For many years, the only known gene controlling SP was Se2.1 [ 23 ], but recently, other positions have been identified [ 46 ] together with new candidate genes [ 12 , 25 ]. The SP variability present in landraces may be exploited to unravel new QTLs for this trait by biparental or linkage disequilibrium-based QTL mapping.…”

“…In many vegetables, such as tomato, reproductive development is more sensitive to and therefore more vulnerable to heat than the vegetative growth [ 9 , 10 ]. Heat effects indicate that in tomato, the male function is generally more exposed to damage than the female one [ 3 , 11 , 12 ]. The most sensitive stage is at early stamen development, when the anther has entered meiosis, which occurs about ten days before anthesis.…”

Reproductive-Stage Heat Stress in Cereals: Impact, Plant Responses and Strategies for Tolerance Improvement

“…[1,[22][23][24][25][26]. In particular, the exposure of plants to above-optimum temperatures (usually by 10-15 • C [1]) at the R stage cause cytological alterations, including loss of membrane integrity, ROS accumulation, and altered carbohydrate and lipid metabolism in mature pollen, resulting in loss of pollen viability [17,19]. Additionally, leaf photosynthesis is severely affected, consequently impacting plant growth and development [27].…”

“…However, HS causes anther indehiscence, for instance, in rice, thus interrupting pollen release [12]. Especially, anther and pollen development at anthesis are very sensitive to temperature instabilities, resulting in compromised reproduction and fertilization processes and, ultimately, reduced seed set and grain yields; structural abnormalities of pollen and pistil, and their decreased functionality, underline seed number reduction under HS [10,17,26]. Pre-anthesis HS (40-45 • C) significantly decreased the seed setting rate and grain quality in rice [32].…”

“…In coping with HS, plants have developed a suite of intricate and diverse short-term acclimation and long-term adaptation mechanisms at various levels, encompassing morphological, whole-plant, cellular, physiological, metabolic and molecular responses [4,17]. Chief among these strategies include altered cellular metabolism, phytohormonal regulation [18], and activation of stress-inducible genes, particularly antioxidant enzymes and Heat Shock Proteins (HSPs) [19].…”