Low Salicylic Acid Level Improves Pollen Development Under Long-Term Mild Heat Conditions in Tomato

Abstract

Exposure to high temperatures leads to failure in pollen development, which may have significant implications for food security with ongoing climate change. We hypothesized that the stress response-associated hormone salicylic acid (SA) affects pollen tolerance to long-term mild heat (LTMH) (≥14 days exposure to day-/nighttime temperature of 30–34/24–28°C, depending on the genotype), either positively, by inducing acclimation, or negatively, by reducing investment in reproductive development. Here, we investigated these hypotheses assessing the pollen thermotolerance of a 35S:nahG tomato line, which has low SA levels. We found that reducing the SA level resulted in increased pollen viability of plants grown in LTMH and further characterized this line by transcriptome, carbohydrate, and hormone analyses. Low expression of JAZ genes in 35S:nahG and LTMH hypersensitivity of low-jasmonic acid (JA) genotypes together suggest that the increased pollen thermotolerance in the low-SA line involves enhanced JA signal in developing anthers in LTMH. These findings have potential application in the development of more thermotolerant crops.

Various tomato cultivars display contrasting morphological and molecular responses to a chronic heat stress

“…Plant hormones signaling pathways, such as abscisic acid, ethylene, salicylic acid and jasmonic acid were proposed to play an important role in plant thermotolerance ( Kotak et al., 2007 ). In particular, salicylic acid has previously been shown to be important for anther and pollen thermotolerance in tomato ( Jansma et al., 2022 ). In our dataset, GO related to hormonal responses including abscisic acid, salicylic acid and jasmonic acid were found enriched indicating that these pathways are affected by the HS in tomato floral buds and the underlying genes could be interesting targets for HS tolerance.…”

High‐temperature stress in crops: male sterility, yield loss and potential remedy approaches

“…Application of JA and salicylic acid (SA) during HT stress at the anther development stage maintains the fertility in cotton and rice (Khan et al, 2020;Zhang et al, 2017). In tomato plants, Jansma et al (2022) found a role for SA in improving pollen viability under long-term mild heat stress conditions. Exogenous application of MeJA on a rice genetic male sterile line not only alleviated damage to anthers but also reduced the ROS in the stigma and increased fertilization under HT stress condition (Chen et al, 2021a).…”

“…In tomato plants, Jansma et al . (2022) found a role for SA in improving pollen viability under long‐term mild heat stress conditions. Exogenous application of MeJA on a rice genetic male sterile line not only alleviated damage to anthers but also reduced the ROS in the stigma and increased fertilization under HT stress condition (Chen et al ., 2021a).…”

“…HT reduced the crop yield by direct damage to enzymes and tissues (Moore et al ., 2021), impaired flowering (Tian et al ., 2012) and triggered oxidative stress at the reproductive stage (Khan et al ., 2022). In addition to this, it was found that the reproductive stage of the crops such as tomato, rice, maize, cotton and soybean is more susceptible to HT stress (Bawa et al ., 2020; Jagtap et al ., 2020; Jansma et al ., 2022; Park et al ., 2021; Wu et al ., 2022a) because, when the temperature rises at the inflorescence/panicle stage or during the flowering stage, the fertility of the crop is reduced, or sometimes the abortion of the flower may occur (Zhang et al ., 2022b).…”

Identification of thermo tolerance urdbean [Vigna mungo (L) Hepper] genotypes using temperature induction response technique

“…HT reduced the crop yield by direct damage to enzymes and tissues (Moore et al, 2021), impaired flowering (Tian et al, 2012), and triggered oxidative stress at the reproductive stage (Khan et al, 2022). In addition to this, it was found that the reproductive stage of crops such as tomato, rice, maize, cotton, and soybean is more susceptible to HT stress (Bawa et al, 2022;Jagtap et al, 2020;Jansma et al, 2022;Park et al, 2021;Wu et al, 2022) because, when the temperature rises at the inflorescence/panicle stage or during the flowering stage, the fertility of the crop is reduced, or sometimes the abortion of the flower may occur (Zhang et al, 2022). The most important effects on the reproductive phase that affect pod set, seed set and yield are flowering time, asynchrony of male and female floral organ development, and impairment of male and female floral organs.…”