Heterogeneous root zone salinity mitigates salt injury to Sorghum bicolor (L.) Moench in a split-root system

• Published in: PloS one Vol. 14; no. 12; p. e0227020
• Main Authors: Zhang, Huawen, Wang, Runfeng, Wang, Hailian, Liu, Bin, Xu, Mengping, Guan, Yan'an, Yang, Yanbing, Qin, Ling, Chen, Erying, Li, Feifei, Huang, Ruidong, Zhou, Yufei
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.12.2019; Public Library of Science (PLoS)
• Subjects: Abiotic stress; Abscisic acid; Abscisic Acid - metabolism; Aquaporins; Aquaporins - metabolism; Biology and Life Sciences; Carrier Proteins - metabolism; Chlorophyll; Crop Production; Crops; Crosstalk; Ecology and Environmental Sciences; Engineering; Environmental conditions; Enzymatic activity; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Plant - drug effects; Gene Expression Regulation, Plant - physiology; Gene sequencing; Genes; Laboratories; Leaves; Metabolism; Molecular modelling; Photosynthesis; Photosynthesis - drug effects; Photosynthesis - genetics; Physical Sciences; Physiology; Plant Leaves - chemistry; Plant Leaves - metabolism; Plant Roots - chemistry; Plant Roots - drug effects; Plant Roots - physiology; Potassium - analysis; Potassium - metabolism; Proteins; Research and Analysis Methods; Rhizosphere; Ribonucleic acid; RNA; Root zone; Roots; Salinity; Salinity distribution; Salinity effects; Salt; Salt Stress; Salt Tolerance - genetics; Salts; Seeds; Sodium - analysis; Sodium - metabolism; Sodium chloride; Sodium Chloride - adverse effects; Soil - chemistry; Soil salinity; Sorghum; Sorghum - physiology; Stress; Transcription factors; Variance analysis; United States > US; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0227020

The heterogeneous distribution of soil salinity across the rhizosphere can moderate salt injury and improve sorghum growth. However, the essential molecular mechanisms used by sorghum to adapt to such environmental conditions remain uncharacterized. The present study evaluated physiological parameters such as the photosynthetic rate, antioxidative enzyme activities, leaf Na+ and K+ contents, and osmolyte contents and investigated gene expression patterns via RNA sequencing (RNA-seq) analysis under various conditions of nonuniformly distributed salt. Totals of 5691 and 2047 differentially expressed genes (DEGs) in the leaves and roots, respectively, were identified by RNA-seq under nonuniform (NaCl-free and 200 mmol·L-1 NaCl) and uniform (100 mmol·L-1 and 100 mmol·L-1 NaCl) salinity conditions. The expression of genes related to photosynthesis, Na+ compartmentalization, phytohormone metabolism, antioxidative enzymes, and transcription factors (TFs) was enhanced in leaves under nonuniform salinity stress compared with uniform salinity stress. Similarly, the expression of the majority of aquaporins and essential mineral transporters was upregulated in the NaCl-free root side in the nonuniform salinity treatment, whereas abscisic acid (ABA)-related and salt stress-responsive TF transcripts were more abundant in the high-saline root side in the nonuniform salinity treatment. In contrast, the expression of the DEGs identified in the nonuniform salinity treatment remained virtually unaffected and was even downregulated in the uniform salinity treatment. The transcriptome findings might be supportive of the increased photosynthetic rate, reduced Na+ levels, increased antioxidative capability in the leaves and, consequently, the growth recovery of sorghum under nonuniform salinity stress as well as the inhibited sorghum growth under uniform salinity conditions. The increased expression of salt resistance genes activated in response to the nonuniform salinity distribution implied that the cross-talk between the nonsaline and high-saline sides of the roots exposed to nonuniform salt stress is potentially regulated.