PGPR regulate caspase-like activity, programmed cell death, and antioxidant enzyme activity in paddy under salinity

Abstract

The response of two root associated bacteria Pseudomonas pseudoalcaligenes and Bacillus pumilus were studied in the (salt-sensitive) rice GJ17 cultivar to salinity under controlled environmental growth conditions for protection of plant from adverse effect of salinity. Salinity affects the growth of salt-sensitive cultivar, but inoculation of plant growth promoting rhizobacteria (PGPR) reduces the harmful effect of salinity. The present study states that PGPR helps to reduce lipid peroxidation and superoxide dismutase activity in salt-sensitive GJ17 cultivar under salinity and play an important role in the growth regulation for positive adaptation of plants to salt stress. This study shows that inoculation of paddy (Oryza sativa) with such bacteria could provide salt-tolerant ability by reducing the toxicity of reactive oxygen species by reducing plant cell membrane index, cell caspase-like protease activity, and programmed cell death and hence resulted in increase cell viability. As these isolates remain associated with the roots, the effects of tolerance against salinity are observed here. Results also indicate that isolated PGPR strain help in alleviating up to 1.5 % salinity stress as well as improve tolerance.

Effects of exogenously applied plant growth regulators in combination with PGPR on the physiology and root growth of chickpea (Cicer arietinum) and their role in drought tolerance

“…The lipid peroxidation showed significant decrease in all the PGPR inoculated and PGR treated plants. Jha and Subramanian (2014) found that inoculation with a single PGPR reduced the lipid peroxidation by 1 time while, combination of 2 PGPR reduced the content up to 1.6 time under salt stress condition. Koc (2015) also reported the negative impacts of plant growth promoting bacteria and arbuscular mycorrhizal fungi on lipid peroxidation and total phenolics of strawberry when grown under stress condition.…”

“…The observed reduction of antioxidant enzymes by the PGPR treatment may be attributed to the fact that PGPR reduced the occurrence of stress induced oxidative stress in plants subsequently the antioxidant enzymes were lesser in PGPR/PGR heated plants. SOD activity was higher in paddy due to salt stress but inoculation of PGPR decreased the SOD activity (Jha and Subramanian 2014). Khan et al (2017) reported that the combined application of PGPR lead to significant decrease in CAT, POD and SOD activities in the leaves of chickpea grown under stress conditont.…”

Plant Growth-Promoting Rhizobacteria Improved Salinity Tolerance of Lactuca sativa and Raphanus sativus

“…Polyamines secreted by PGPR have also been exposed to mitigate stress ethylene levels and alleviate osmotic stress [30,31]. PGPR have been demonstrated to activate the synthesis of antioxidants and indole acetic acid, which can stimulate root growth [28,32,33]. Recently, PGPR were shown to alter mineral uptake, which results in a favorable increase in the cellular ratio of K+/Na+; and elevated generation of quorum-sensing molecules, which can lead to modifications in the rhizosphere [34][35][36].…”

Native halo-tolerant plant growth promoting rhizobacteria Enterococcus and Pantoea sp. improve seed yield of Mungbean (Vigna radiata L.) under soil salinity by reducing sodium uptake and stress injury

“…Although PGPR application reduced the MDA concentration, maximum reduction (by 39 %) was recorded with combination treatment at both the salt stress conditions. Lower MDA concentration represents less membrane damage or increased salt tolerance of the plants (Jha and Subramanian 2014).…”