• ISSN 1008-505X
  • CN 11-3996/S
SUN Jia-lin, HOU Zhen-an. Effect of phosphorus on ionic balance and expression of related regulatory genes of cotton under salt and alkali stresses[J]. Journal of Plant Nutrition and Fertilizers, 2022, 28(4): 643-653. DOI: 10.11674/zwyf.2021324
Citation: SUN Jia-lin, HOU Zhen-an. Effect of phosphorus on ionic balance and expression of related regulatory genes of cotton under salt and alkali stresses[J]. Journal of Plant Nutrition and Fertilizers, 2022, 28(4): 643-653. DOI: 10.11674/zwyf.2021324

Effect of phosphorus on ionic balance and expression of related regulatory genes of cotton under salt and alkali stresses

  • Objectives Salt stress is one of the major abiotic stresses affecting the growth of cotton in Xinjiang, and proper fertilization for efficient uptake of nutrient ions under salt stress is an important way to improve salt tolerance in crops. We studied effect of phosphorus on cotton salinity tolerance via the ionome response characteristics and the expression of Na+ transport-related genes.
    Methods A cotton pot experiment was conducted, and the stress treatments were prepared by adding NaCl and NaHCO3 + Na2CO3 as salt and base stress treatments, respectively. Under each stress condition, cotton plants were sprayed with 0 (P0), 0.5% (P0.5) and 0.75% (P0.75) of phosphorus fertilizer at three-leaf-stage while the cotton in normal soil was sprayed with water (control). Cotton growth (biomass, root length, root surface area) and physiological indicators of adversity (relative permeability of the plasma membrane, malondialdehyde) were measured to study the effects of phosphorus on salinity tolerance in cotton. The ion content of cotton organs (roots, stems and leaves) was analyzed to elucidate the response characteristics of the cotton ionome. The relative expression levels of GhSOS1 (Na+ transport regulation related gene), GhNHX1 (Na+ compartmental gene), GhAKT1 (K+ transport gene) and GhVP1 (H+-translocating pyrophosphatases gene) in leaves were determined.
    Results Compared with P0, P0.5 and P0.75 treatments increased relative biomass of cotton by 23.8% and 34.7% under salt stress, and by 17.3% and 21.1% under alkali stress. Compared with P0 treatment, P0.75 treatment increased cotton root length and root surface area by 74.6% and 49.4% under salt stress, respectively. However, spraying P had no significant effect on cotton root length under alkali stress. The relative permeability of plasma membrane and the content of malondialdehyde in cotton leaves were significantly reduced by spraying phosphorus, and the effect of alleviating salt stress was greater than that of alkaline stress. Under salt and alkali stress, however, the decrease of Na content and the increase of Cu and Si content under salt stress were greater than those under alkali stress. In cotton roots, only Na content was significantly reduced by spraying phosphorus under salt stress, while the content of Ca, Zn, P, and Fe significantly increased, and the content of other ions did not change under salt and alkali stress. K/Na in various organs of cotton increased significantly with the increase of phosphorus levels. This indicated that the ion group of cotton leaves changed in a similar trend under different saline stresses, but the promotion effect of salt stress on ion root uptake in cotton was greater than that of alkali stress. Under salt and alkali stresses, the application of phosphorus significantly increased the relative expression of GhSOS1, GhNHX1, GhAKT1 and GhVP1, which may promote Na+ efflux and compartmentalization in cotton leaves, and the synthesis of tonoplast H+-transport pyrophosphatase. Under alkaline stress, it may greatly poromote K+ transport, which was significantly greater than that under salt stress.
    Conclusions Phosphorus spray on leaves can promote the growth of cotton under salt stress, up-regulate the expression of genes related to Na+ transport regulation, reduce leaf Na content, promote nutrient ion uptake and transport, maintain ion homeostasis, and thus improve salt tolerance in cotton. However, it has less alleviating effect on alkali stress.
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