Cotton (Gossypium hirsutum L.) genotypes with contrasting K+/Na+ ion homeostasis: implications for salinity tolerance
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Cotton (Gossypium hirsutum L.) possesses notable inter- and intraspecific salt tolerance variation, but the mechanisms underlying this variation are, more or less, unclear. To explore salt stress responses, Na+/K+ transport and the transcriptional profiles of salinity tolerance candidate genes (e.g., GhSOS1, GhNHX1, and GhAKT1) were evaluated in four cotton cultivars (differing in salt sensitivities) using electrophysiological and qRT-PCR assays. Physiology and lipid peroxidation assays revealed the following pattern of salt tolerance, in decreasing order: CZ91 > CCRI44 > CCRI49 > Z571. Salinity caused ion imbalances in plants, but ion homeostasis was more pronounced in Z571, which accumulated more Na+ and less K+ in leaves. In contrast, salt-tolerant cultivars, especially CZ91, retained less Na+, but more K+ under salt stress. The non-invasive micro-test technique revealed that Z571 exhibited a higher capacity to transport Na+ from roots to shoots, but a lower capacity to extrude Na+ and retain K+ in leaves under salinity. Meanwhile, NaCl-induced changes in Na+ and K+ ion homeostasis were less pronounced in salt-tolerant cultivars, increasing leaf K+/Na+ ratios under salinity. Additionally, NaCl increased the GhSOS1 transcript abundance in hypocotyls, but this increase was more pronounced in salt-sensitive Z571. On the other hand, NaCl significantly enhanced the transcript abundances of GhSOS1 in leaves and/or GhAKT1 in hypocotyls of salt-tolerant cultivars. NaCl also increased the GhNHX1 transcript abundance, but there was no strong correlation between GhNHX1 expression level and salt resistance. The present findings provided an explanation for salt tolerance variation in cotton, illuminating the transcriptional regulation of K+/Na+ transport and the maintenance of the K+/Na+ ratio as underlying attributes.
KeywordsSodium exclusion Sodium sequestration Potassium retention Non-invasive micro-test technique Ion fluxes
This work was supported by the Modern Agricultural Industry Technology System in Henan (No. S2013-07-1), the China Agricultural Research System (No. CARS-18-05) and Innovation Project of the Chinese Academy of Agricultural Sciences (No. CAAS-ASTIP-2016-CCRI).
- Chen J, Xiong DY, Wang WH, Hu WJ, Simon M, Xiao Q, Liu TW, Liu X, Zheng HL (2013) Nitric oxide mediates root K+/Na+ balance in a mangrove plant, Kandelia obovata, by enhancing the expression of AKT1-Type K+ channel and Na+/H+ antiporter under high salinity. PLoS One 8(8):1–11Google Scholar
- Lei B, Huang Y, Sun J, Xie JJ, Niu ML, Liu ZX, Fan ML, Bie ZL (2014) Scanning ion-selective electrode technique and X-ray microanalysis provide direct evidence of contrasting Na+ transport ability from root to shoot in salt-sensitive cucumber and salt-tolerant pumpkin under NaCl stress. Physiol Plantarum 152:738–748CrossRefGoogle Scholar
- Singh PK, Shahi SK, Singh AP (2015) Effects of salt stress on physico-chemical changes in maize (Zea mays L.) plants in response to salicylic acid. Indian J Plant Sci 4:69–77Google Scholar