AUTHOR=Prerostova Sylva , Jarosova Jana , Dobrev Petre I. , Hluskova Lucia , Motyka Vaclav , Filepova Roberta , Knirsch Vojtech , Gaudinova Alena , Kieber Joseph , Vankova Radomira 

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

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.799249

DOI=10.3389/fpls.2021.799249

ISSN=1664-462X

ABSTRACT=<p>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 (<italic>Oryza sativa</italic>) by comparing the impact of HS applied either to whole plants, or only to shoots or roots. Whole-plant HS reduced photosynthetic activity (F<sub><italic>v</italic></sub>/F<sub><italic>m</italic></sub> and QY<sub>_<italic>Lss</italic></sub>), but this effect was alleviated by prior acclimation (37°C, 2 h). Dynamics of <italic>HSFA2d</italic>, <italic>HSP90.2</italic>, <italic>HSP90.3</italic>, and <italic>SIG5</italic> expression revealed high protection of crowns and roots. Additionally, <italic>HSP26.2</italic> was strongly expressed in leaves. Whole-plant HS increased levels of jasmonic acid (JA) and cytokinin <italic>cis</italic>-zeatin in leaves, while up-regulating auxin indole-3-acetic acid and down-regulating <italic>trans</italic>-zeatin in leaves and crowns. Ascorbate peroxidase activity and expression of alternative oxidases (<italic>AOX</italic>) increased in leaves and crowns. HS targeted to leaves elevated levels of JA in roots, <italic>cis</italic>-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, <italic>cis</italic>-zeatin in leaves, and JA in crowns, while reducing <italic>trans</italic>-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.</p>