Mondal Subhankar, Panda Babyrani, Nayak Jajati Keshari, Pradhan Chinmay, Chattopadhyay Krisnendu, Chakraborty Koushik
Crop Physiology and Biochemistry Division, ICAR-Central Rice Research Institute, Cuttack, Odisha, 753006, India.
Department of Botany, Utkal University, Vani Vihar, Bhubaneswar, Odisha, 751004, India.
Ann Bot. 2025 Jun 25. doi: 10.1093/aob/mcaf134.
BACKGROUND & AIMS: Increasing soil salinity is an emerging and potent threat to agricultural crop production. Plant root tissues are the most important place for salt sensing. Thus, root traits associated with salt tolerance are very important. Identification of new root traits may help us to optimize plants' overall performance under stress.
An experiment was conducted with eight rice genotypes and root aerenchymatous gas space, Na+, and K+ concentrations of root and leaf were measured. A further experiment was performed with four selected rice genotypes based on morphological, physiological, biochemical, and molecular traits.
We identified root tissue porosity and root aerenchymatous gas space was increased under salt stress and the induction of these traits was greater in salt-tolerant genotypes (FL478, AC39416A, and Rashpanjor) as compared to salt-susceptible genotype (Naveen). Most interestingly, root porosity and aerenchymatous gas space showed a strong correlation with leaf Na+ ion concentration as well as leaf and root K+ ion retention. Thereby, it seems more porous roots can play an important role in Na+ transport and K+ retention in salt-tolerant rice plants. Additionally, we observe relatively higher expression of ROS-induced NADPH oxidases (OsNOX5 and OsNOX9) genes in FL478, AC39416A, and Rashpanjor as compared to Naveen, whose function is associated with programmed cell death (PCD) and lysegenous aerenchyma formation in rice.
Overall the findings suggest that tolerant and moderately tolerant rice genotypes followed PCD in root cortical tissues that help to restrict upward movement of Na+ and retention of K+ in rice under saline conditions.
土壤盐度增加是对农作物生产新出现的重大威胁。植物根系组织是感知盐分的最重要部位。因此，与耐盐性相关的根系性状非常重要。鉴定新的根系性状可能有助于我们优化植物在胁迫下的整体表现。
以8个水稻基因型进行实验，测定根系通气组织气腔、根和叶中钠（Na+）和钾（K+）的浓度。基于形态、生理、生化和分子性状，对4个选定的水稻基因型进行了进一步实验。
我们发现盐胁迫下根系组织孔隙率和根系通气组织气腔增加，与盐敏感基因型（Naveen）相比，耐盐基因型（FL478、AC39416A和Rashpanjor）中这些性状的诱导作用更强。最有趣的是，根系孔隙率和通气组织气腔与叶片Na+离子浓度以及叶片和根系K+离子保留呈强相关。因此，根系孔隙率较高似乎在耐盐水稻植株的Na+转运和K+保留中发挥重要作用。此外，我们观察到与Naveen相比，FL478、AC39416A和Rashpanjor中ROS诱导的NADPH氧化酶（OsNOX5和OsNOX9）基因表达相对较高，其功能与水稻程序性细胞死亡（PCD）和裂生性通气组织形成有关。
总体而言，研究结果表明，耐盐和中度耐盐水稻基因型在根皮层组织中发生PCD，这有助于在盐胁迫条件下限制水稻中Na+的向上移动和K+的保留。
