Fast Regulation of Hormone Metabolism Contributes to Salt Tolerance in Rice (Oryza sativa spp. Japonica, L.) by Inducing Specific Morpho-Physiological Responses

Abstract

Clear evidence has highlighted a role for hormones in the plant stress response, including salt stress. Interplay and cross-talk among different hormonal pathways are of vital importance in abiotic stress tolerance. A genome-wide transcriptional analysis was performed on leaves and roots of three-day salt treated and untreated plants of two Italian rice varieties, Baldo and Vialone Nano, which differ in salt sensitivity. Genes correlated with hormonal pathways were identified and analyzed. The contents of abscisic acid, indoleacetic acid, cytokinins, and gibberellins were measured in roots, stems, and leaves of seedlings exposed for one and three days to salt stress. From the transcriptomic analysis, a huge number of genes emerged as being involved in hormone regulation in response to salt stress. The expression profile of genes involved in biosynthesis, signaling, response, catabolism, and conjugation of phytohormones was analyzed and integrated with the measurements of hormones in roots, stems, and leaves of seedlings. Significant changes in the hormone levels, along with differences in morphological responses, emerged between the two varieties. These results support the faster regulation of hormones metabolism in the tolerant variety that allows a prompt growth reprogramming and the setting up of an acclimation program, leading to specific morpho-physiological responses and growth recovery.

A Meta-Analysis of Comparative Transcriptomic Data Reveals a Set of Key Genes Involved in the Tolerance to Abiotic Stresses in Rice

“…The loss of DST function increases stomatal closure and reduces stomata density, consequently resulting in enhanced drought and salt tolerance in rice [92]. Our previous finding that salt-tolerant plants are able to close stomata more efficiently than salt-sensitive plants [32,46] is consistent with the putative upstream role of DST in the tolerance response. DST regulates the expression of genes that are related to H 2 O 2 homeostasis, through the formation of a transcriptional complex with another TF, the “DST Co-activator 1” (DCA1) [94].…”

“…This difference can be ascribed to a delay of the response of the salt-susceptible genotype. Consistently, Formentin and colleagues [46,47] demonstrated that the salt-tolerant genotype is able to activate a faster stress response as compared to the salt-susceptible genotype, through an early activation of H 2 O 2 and hormone signalling pathways.…”

“…Previously, OsABA8ox1 was shown to be up-regulated in roots under short-term osmotic stress in the tolerant cultivar Eurosis, but not in the susceptible Loto, and it was hypothesized that the encoded hydroxylase might contribute to the tolerant response of Eurosis through the reduction of ROS, which are produced during ABA signalling [28]. It was also demonstrated that the reduced ABA content in leaves of the salt-tolerant variety Baldo was related to tolerance and was linked to the down-regulation of OsABA8ox1 [46]. Moreover, the overexpression of OsABA8ox1 in rice highlighted that this gene is a master regulator of the abiotic stress response through the control of ABA level, whose fluctuation might vary the tolerance of rice to abiotic stresses [60].…”

“…Moreover, the overexpression of OsABA8ox1 in rice highlighted that this gene is a master regulator of the abiotic stress response through the control of ABA level, whose fluctuation might vary the tolerance of rice to abiotic stresses [60]. Therefore, the adequate regulation of endogenous ABA levels, that is due, at least in part, to the activity of OsABA8ox1 , is thought to be crucial for tolerance in rice [28,46,60].…”

Systematic hormone-metabolite network provides insights of high salinity tolerance inPongamia pinnata(L.) pierre

“…Further, JA also showed strong interaction with organic acids and amino acids with the salinity treatment time suggesting that organic acids and amino acids may be involved in promoting salt-induced growth by regulating osmotic balance, ion homeostasis, carbon and nitrogen balance under salt stress (Sharma et al, 2018; Siddiqi Husen, 2019). The results suggest that the increased interaction between hormones and metabolites may be beneficial for Pongamia to survive under extreme salinity stress (Sahoo et al, 2014; Formentin et al, 2018).…”