High Performance of Photosynthesis and Osmotic Adjustment Are Associated With Salt Tolerance Ability in Rice Carrying Drought Tolerance QTL: Physiological and Co-expression Network Analysis

Abstract

Understanding specific biological processes involving in salt tolerance mechanisms is important for improving traits conferring tolerance to salinity, one of the most important abiotic stresses in plants. Under drought and salinity stresses, plants share overlapping responsive mechanisms such as physiological changes and activation of signaling molecules, which induce and transmit signals through regulator genes in a regulatory network. In this study, two near isogenic lines of rice carrying chromosome segments of drought tolerance QTL on chromosome 8 from IR68586-F2-CA-31 (DH103) in the genetic background of sensitive cultivar “Khao Dawk Mali 105; KDML105” (designated as CSSL8-94 and CSSL8-95) were used to investigate physiological responses to salt stress [namely growth, Na+/K+ ratio, water status, osmotic adjustment, photosynthetic parameters, electrolyte leakage (EL), malondialdehyde (MDA), proline and sugar accumulations], compared with the standard salt tolerant (Pokkali; PK) and their recurrent parent (KDML105) rice cultivars. Physiological examination indicated that both CSSLs showed superior salt-tolerant level to KDML105. Our results suggested that salt tolerance ability of these CSSL lines may be resulted from high performance photosynthesis, better osmotic adjustment, and less oxidative stress damage under salt conditions. Moreover, to explore new candidate genes that might take part in salt tolerance mechanisms, we performed co-expression network analysis for genes identified in the CSSL rice, and found that Os08g419090, the gene involved with tetrapyrrole and porphyrin biosynthetic process (chlorophyll biosynthetic process), Os08g43230 and Os08g43440 (encoded TraB family protein and cytochrome P450, respectively) might have unprecedented roles in salt stress tolerance.

Stomatal and Photosynthetic Traits Are Associated with Investigating Sodium Chloride Tolerance of Brassica napus L. Cultivars

“…Severe salt stress caused a greater reduction in photosynthetic gas exchange parameters in the salt-sensitive relative to the salt tolerant cultivars. These findings are consistent with Nounjan et al [27] who reported that protecting the photosynthetic process from damage led to high-performance photosynthesis and thus salt tolerance in rice CSSL lines. Our result showed that strong correlation between SAA and the Pn, Tr, and Gs.…”

“…It was reported that the level of antioxidant enzymes rises when plants are exposed to oxidative stress including salt stress [18,25,26]. Analysis of chlorophyll content and chlorophyll-based parameters are considered as an important way to evaluate the integrity during the photosynthetic process under salt stress, while the high performance of photosynthesis was reported to associate with salt tolerance ability [27,28]. In addition, biosynthesis of osmoprotectants and compatible solutes: e.g., proline and sugar) considered an adaptive role in mediating osmotic adjustment and protecting the sub-cellular structures in salt stressed plants [6].…”

Genetic Diversity, Population Structure, and Marker-Trait Association for Drought Tolerance in US Rice Germplasm

“…Few salt-tolerant rice genotypes like Damodar, Cypress, Caffey, Jupiter, and Jazzman [21] showed drought tolerance under the greenhouse conditions. The rice genotypes showing both salt and drought tolerance may be due to similar physiological responses and co-expression of the genes under both stress conditions [22].…”

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

“…A vast amount of literature addressing the salt stress response in plant has been published [ 2 ]. Recently, some molecular players involved in mechanisms of salt tolerance have been unveiled in several plant species [ 6 , 7 ], including rice [ 8 , 9 , 10 ]. Despite these efforts, however, few fundamental findings have been successfully applied to crop plants [ 11 ].…”