Potassium application alleviates the negative effects of salt stress on cotton (Gossypium hirsutum L.) yield by improving the ionic homeostasis, photosynthetic capacity and carbohydrate metabolism of the leaf subtending the cotton boll

Abstract Salinization leads to several worldwide damages in agricultural regions, mainly in semiarid regions where leaching of salt is poor due to limited and erratic rainfall. Cotton (Gossypium hirsutum L.) is a Malvaceae with wide genetic variability to salt stress. The identification of salinity tolerant genotypes is a dynamic target in a breeding program, and the selection is often based on plant phenotypes. Molecular markers are reliable tools to aid in these selection procedures. Aquaporin (AQPs) are channel proteins that play fundamental role in water relations and tolerance to environmental stresses. Plants have fine regulation of water transport through AQPs activities. In order to evaluate the AQP expressions of different cotton cultivars submitted to salt stress, we use molecular and physiological tools, based on RT-qPCR and gas exchange assays. Seven cultivars were submitted to 95 mM NaCl, started at V3 stage (21 days after emergence), during 72 h. At the end of stress treatment, root tissues were used to total RNA extraction, followed by cDNA synthesis and RT-qPCR analyzes. Three sets of specific primers were used, drawn from AQP accessions deposited in NCBI. Additionally, full expanded leaves were used to gas exchange assays and to estimate the relative water content. The dry matter of the shoots was also evaluated. Based on pattern of AQPs transcripts, we found that all semiarid tolerant cultivars (BRS Seridó, 7MH, CNPA MT 2009 152 and BRS 416) showed downregulation of AQP subtypes, mainly GhPIP1;1 and GhTIP2;1 whose action is characterized as tolerant to salinity. The results of gas exchanges, relative water content and dry matter were consistent with the molecular findings in these cultivars, confirming that GhPIP1;1 and GhTIP2;1, located at plasma membrane and vacuoles, respectively, could be adopted as AQP markers for identification of cotton tolerant to salt stress.

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Knockdown of Cytochrome P450 Genes Gh_D07G1197 and Gh_A13G2057 on Chromosomes D07 and A13 Reveals Their Putative Role in Enhancing Drought and Salt Stress Tolerance in Gossypium hirsutum

Genes ◽

10.3390/genes10030226 ◽

2019 ◽

Vol 10 (3) ◽

pp. 226 ◽

Cited By ~ 10

Author(s):

Richard Odongo Magwanga ◽

Pu Lu ◽

Joy Nyangasi Kirungu ◽

Qi Dong ◽

Xiaoyan Cai ◽

...

Keyword(s):

Salt Stress ◽

Gossypium Hirsutum ◽

Stress Tolerance ◽

Common Property ◽

Stress Conditions ◽

Tetraploid Cotton ◽

Salt Stress Tolerance ◽

Negative Effects ◽

Drought And Salt Stress ◽

Stress Responsive Genes

We identified 672, 374, and 379 CYPs proteins encoded by the CYPs genes in Gossypium hirsutum, Gossypium raimondii, and Gossypium arboreum, respectively. The genes were found to be distributed in all 26 chromosomes of the tetraploid cotton, with chrA05, chrA12, and their homeolog chromosomes harboring the highest number of genes. The physiochemical properties of the proteins encoded by the CYP450 genes varied in terms of their protein lengths, molecular weight, isoelectric points (pI), and even grand hydropathy values (GRAVY). However, over 99% of the cotton proteins had GRAVY values below 0, which indicated that the majority of the proteins encoded by the CYP450 genes were hydrophilic in nature, a common property of proteins encoded by stress-responsive genes. Moreover, through the RNA interference (RNAi) technique, the expression levels of Gh_D07G1197 and Gh_A13G2057 were suppressed, and the silenced plants showed a higher concentration of hydrogen peroxide (H2O2) with a significant reduction in the concentration levels of glutathione (GSH), ascorbate peroxidase (APX), and proline compared to the wild types under drought and salt stress conditions. Furthermore, the stress-responsive genes 1-Pyrroline–5-Carboxylate Synthetase (GhP5CS), superoxide dismutase (GhSOD), and myeloblastosis (GhMYB) were downregulated in VIGS plants, but showed upregulation in the leaf tissues of the wild types under drought and salt stress conditions. In addition, CYP450-silenced cotton plants exhibited a high level of oxidative injury due to high levels of oxidant enzymes, in addition to negative effects on CMS, ELWL, RLWC, and chlorophyll content The results provide the basic foundation for future exploration of the proteins encoded by the CYP450 genes in order to understand the physiological and biochemical mechanisms in enhancing drought and salt stress tolerance in plants.

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