Genotypic variations in ion homeostasis, photochemical efficiency and antioxidant capacity adjustment to salinity in cotton (Gossypium hirsutumL.)

Abstract

To determine the genotypic variation in response to salt (NaCl) stress in cotton (Gossypium hirsutum L.) seedlings, potassium (K +) and sodium (Na +) homeostasis, photochemical energy utility, reactive oxygen metabolism and the activity of antioxidant enzymes were comparatively analyzed in three cotton cultivars (CCRI 49, CCRI 35 and Z 51504) under salt constraint. The results showed that NaCl treatment significantly inhibited biomass accumulation, and the extent of inhibition was highest in CCRI 49 and lowest in Z 51504. Salinity caused an ion imbalance in plants but ion homeostasis was less pronounced in Z 51504, as it accumulated more K + and less Na +. Experiments of salt shock treatment were tested using a non-invasive micro-test (NMT) system, which also revealed that Z 51504 had lower Na + influx and better K + retention. Salinity increased excess-energy dissipation [non-photochemical quenching (qN) and photorespiration rate (PR)], but depressed photochemical efficiency such as photosynthesis rate (P n), quenching (qP), photochemical quantum yield of photosystem (Φ PSII) and electron transport rate (ETR). As a result, more electrons were driven to other sinks, for example decreasing ETR/P n and increasing the O 2 − generation rate. However, the superior tolerance of Z 51504 had a better balance of photochemical energy under salt conditions, displayed higher photochemical efficiency and excess-energy dissipation. Furthermore, the antioxidant enzyme activities were also affected by salt stress and less effectively removed reactive oxygen species. The antioxidant enzyme activities of Z 51504 were higher than those of CCRI 49 and CCRI 35, which resulted in lower levels of reactive oxygen species (ROS) and mitigated the salt-induced membrane lipid peroxidation. The overall results indicated that more effective retention of ions, photochemical energy utility and ROSremoving capability were probably the main reasons for the stronger salt tolerance in Z 51504.

Physiological, biochemical, and antioxidant properties of two genotypes of Vicia faba grown under salinity stress

“…Salinity stress tolerance in plants is reportedly conferred by K + retention and Na + exclusion from the shoots (Shabala, 2017). Positive correlations between K + retention in plant tissues and salinity tolerance have been reported in wheat (Wu et al, 2015), alfalfa (Guo et al, 2016), cotton (Wang et al, 2016), mustard (Chakraborty et al, 2016), and cucumber (Redwan et al, 2016). Salt tolerant genotypes maintain high K + /Na + ratios under salinity stress; this has been reported by Wu et al, (2015) in barley and by Xiong et al, (2018) in melon.…”

Signalling by potassium: another second messenger to add to the list?

“…Over the past decade, cytosolic potassium homeostasis and the ability of various plant tissues to retain potassium under stress conditions have emerged as novel and essential mechanisms of salinity stress tolerance in plants (reviewed by Shabala and Pottosin, 2014 ; Shabala et al , 2016 a ). Reported initially for barley roots ( Chen et al ., 2005 , 2007 a ,b), a positive correlation between the overall salinity stress tolerance and the ability of root tissue to retain K + was later expanded to other plant species such as wheat ( Cuin et al ., 2008 , 2009 ), lucerne ( Smethurst et al , 2008 ; Guo et al , 2016 ), pepper ( Bojorquez-Quintal et al , 2016 ), cotton ( Wang et al , 2016 b ), cucumber ( Redwan et al , 2016 ), and Arabidopsis ( Sun et al , 2015 ). This trait also explains the inter-specific variability in salinity stress tolerance (poplar – Sun et al , 2009 ; mangroves – Lu et al , 2013 ; Brassica – Chakraborty et al , 2016 ), and has recently emerged as a novel (and essentially overlooked) mechanism of salinity tissue tolerance in shoots ( Wu et al ., 2013 , 2015 ).…”

Two‐year study on combining ability and heterotic potential in functional traits under salt stress in upland cotton (Gossypium hirsutum)

“…3) The interaction of favourable alleles at different loci can improve the character more than without this interaction (Abro et al., 2009). The presence of variation in the performance of the parents compared to hybrid development programmes can be attributed to differences in the genetic constitution of the plants and their specific interaction with the prevailing environment (Wang et al, 2016). Previously, several initiatives have been undertaken to study the molecular basis of heterosis and to reveal the number and types of QTLs associated with the phenomenon of heterosis.…”