Heat Stress Targeting Individual Organs Reveals the Central Role of Roots and Crowns in Rice Stress Responses

Abstract

Inter-organ communication and the heat stress (HS; 45°C, 6 h) responses of organs exposed and not directly exposed to HS were evaluated in rice (Oryza sativa) by comparing the impact of HS applied either to whole plants, or only to shoots or roots. Whole-plant HS reduced photosynthetic activity (Fv/Fm and QY_Lss), but this effect was alleviated by prior acclimation (37°C, 2 h). Dynamics of HSFA2d, HSP90.2, HSP90.3, and SIG5 expression revealed high protection of crowns and roots. Additionally, HSP26.2 was strongly expressed in leaves. Whole-plant HS increased levels of jasmonic acid (JA) and cytokinin cis-zeatin in leaves, while up-regulating auxin indole-3-acetic acid and down-regulating trans-zeatin in leaves and crowns. Ascorbate peroxidase activity and expression of alternative oxidases (AOX) increased in leaves and crowns. HS targeted to leaves elevated levels of JA in roots, cis-zeatin in crowns, and ascorbate peroxidase activity in crowns and roots. HS targeted to roots increased levels of abscisic acid and auxin in leaves and crowns, cis-zeatin in leaves, and JA in crowns, while reducing trans-zeatin levels. The weaker protection of leaves reflects the growth strategy of rice. HS treatment of individual organs induced changes in phytohormone levels and antioxidant enzyme activity in non-exposed organs, in order to enhance plant stress tolerance.

Positively Charged Microplastics Induce Strong Lettuce Stress Responses from Physiological, Transcriptomic, and Metabolomic Perspectives

“…Zeatin is a typical cytokinin plant hormone, a regulator of plant growth . In different plant species, stress conditions were reported to elevate levels of zeatin. − The genes related to zeatin also showed an increasing trend with the increase in MPs levels, suggesting that the increase of zeatin could be a potential response mechanism of lettuce to MP stress.…”

Effect of ascorbate and hydrogen peroxide on hormone and metabolite levels during post‐germination growth in wheat

“…Elevation of the stress‐related active cytokinin cZ seems to reflect mild/moderate oxidative stress/redox disbalance caused by both treatments (Gajdošová et al, 2011; Prerostova et al, 2022). Interestingly, the amounts of cytokinin ribosides, O ‐ and N ‐glucosides were greatly reduced by ASA and H 2 O 2 (with exception of 5 mM ASA).…”

“…Thus, cytokinins decreased H 2 O 2 levels through their effects on GSH in rose, which resulted in initiation of bud outgrowth (Porcher et al, 2021). In addition, cytokinins promoted CAT and APX activities and reduced ROS levels in wheat (Lubovská et al, 2014; Prerostova et al, 2022; Zavaleta‐Mancera et al, 2007). Modulation of cytokinin levels was found to affect the antioxidant enzyme system both in control and stress conditions (Lubovská et al, 2014).…”

How rice adapts to high temperatures

“…In addition, the tiller angle between the main stem of rice and its side tillers also directly affects the photosynthetic rate, and thus affects the rice yield per unit area (Li et al, 2020a). Recent studies have shown that the expression of HEAT SHOCK FACTOR A2d (HSFA2d) increases rapidly only 15 min after HS, and the formation of rice tiller angle can be regulated by HSFA2D-LA1 (LAZY1) pathway in rice (Zhang N et al, 2018;Hu et al, 2020;Prerostova et al, 2021). Therefore, the phenotypic characteristics of tillers can also be used as one of the screening criteria for thermoresistant varieties.…”