Growth and Molecular Responses of Tomato to Prolonged and Short-Term Heat Exposure

Abstract

Tomatoes are one of the most important vegetables for human consumption. In the Mediterranean’s semi-arid and arid regions, where tomatoes are grown in the field, global average surface temperatures are predicted to increase. We investigated tomato seed germination at elevated temperatures and the impact of two different heat regimes on seedlings and adult plants. Selected exposures to 37 °C and heat waves at 45 °C mirrored frequent summer conditions in areas with a continental climate. Exposure to 37 °C or 45 °C differently affected seedlings’ root development. Both heat stresses inhibited primary root length, while lateral root number was significantly suppressed only after exposure to 37 °C. Heat stress treatments induced significant accumulation of indole-3-acetic acid (IAA) and reduced abscisic acid (ABA) levels in seedlings. As opposed to the heat wave treatment, exposure to 37 °C increased the accumulation of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), which may have been involved in the root architecture modification of seedlings. Generally, more drastic phenotypic changes (chlorosis and wilting of leaves and bending of stems) were found in both seedlings and adult plants after the heat wave-like treatment. This was also reflected by proline, malondialdehyde and heat shock protein HSP90 accumulation. The gene expression of heat stress-related transcription factors was perturbed and DREB1 was shown to be the most consistent heat stress marker.

Deleterious Effects of Heat Stress on the Tomato, Its Innate Responses, and Potential Preventive Strategies in the Realm of Emerging Technologies

“…In the same study, tomato seedlings aged 12 days (germination: 24 • C) were exposed to 37 • C for 24 h, and a 1 h heat wave (45 • C) damaged the seedling's recovery ability. Exposure to a 45 • C heat wave for 1 h, 3 h, 6 h, and 12 h showed that the seedlings started drying at 6 h and lost recovery capability at 12 h. The number of lateral roots was reduced, but the growth of the primary root was stopped at 37 • C. Although 45 • C did not affect lateral roots significantly, it halted the growth of the primary root [32,33]. High temperature reduces tomato root growth and nutrient uptake, affecting root-shoot source-sink relationships that affect fruit yield and quality [28,34].…”

Regenerative strategies of Euterpe edulis (Arecaceae) at its altitudinal limits in the Atlantic Forest

“…Not all strategies used by plants to cope with stress are successful, and some symptoms, such as fruit weight reduction, seed abortion and reduced seed filling, may be observed (Martínez‐Lüscher et al., 2020; Swetha et al., 2021). Studies show that heat waves at temperatures of 37–45°C in the first 24 h are sufficient to generate deleterious effects on seeds (Martínez‐Lüscher et al., 2020; Swetha et al., 2021; Tokić et al., 2023). However, this condition may be related to the thermal tolerance of the species.…”