Alleviation of drought stress in pulse crops with ACC deaminase producing rhizobacteria isolated from acidic soil of Northeast India

Abstract

The agricultural crops are often affected by the scarcity of fresh water. Seasonal drought is a major constraint on Northeast Indian agriculture. Almost 80% of the agricultural land in this region is acidic and facing severe drought during the winter period. Apart from classical breeding and transgenic approaches, the application of plant-growth-promoting bacteria (PGPB) is an alternative strategy for improving plant fitness under stressful conditions. The 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing PGPB offer drought stress tolerance by regulating plant ethylene levels. The aim of the present study was to evaluate the consortium effect of three ACC-deaminase producing rhizobacteria – Ochrobactrum pseudogrignonenseRJ12, Pseudomonas sp.RJ15 and Bacillus subtilisRJ46 on drought stress alleviation in Vigna mungo L. and Pisum sativum L. Consortium treatment significantly increase seed germination percentage, root length, shoot length, and dry weight of treated plants. An elevated production of reactive oxygen species scavenging enzymes and cellular osmolytes; higher leaf chlorophyll content; increase in relative water content and root recovery intension were observed after consortium treatment in comparison with the uninoculated plants under drought conditions. The consortium treatment decreased the ACC accumulation and down-regulated ACC-oxidase gene expression. This consortium could be an effective bio-formulator for crop health improvement in drought-affected acidic agricultural fields.

Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

“…For instance, volatile organic compounds such as acetoin and butanediol elicits stomatal closure, helping the plant prevent water loss from transpiration (Cho et al, 2008) and improving drought tolerance (Saha and Bothast, 1999;Celińska and Grajek, 2009;Ji et al, 2011;Khalifa et al, 2016). In addition, Pseudomonas, Klebsiella, Erwinia, Serratia and Pantoea species are known to be ACC deaminase-producing bacteria and therefore able to regulate plant ethylene levels inducing tolerance to drought stress (Li et al, 2015;Saikia et al, 2018;Danish and Zafar-ul-Hye, 2019). Therefore, while climate and weather data had a limited impact on microbial community composition, community ASVs significantly correlated with environmental constraints such as vapor pressure deficit could enhance drought tolerance in plant inhabiting hot-dry environments.…”

Plant Growth Promoting Rhizobacterial Mitigation of Drought Stress in Crop Plants: Implications for Sustainable Agriculture

“…Ochrobactrum pseudogrignonense strain RJ12, which produced high levels of IAA under the osmotic stress condition of −0.73 MPa (85.0 ± 1.0 µg mL −1 ) when combined in a consortium with Pseudomonas sp. strain RJ15 (72.0 ± 1.1 µg mL −1 ) and Bacillus subtilis strain RJ46 (68.0 ± 0.9 µg mL −1 ), significantly increased the root length of black gram (12.1 ± 0.9 cm) and garden pea (10.2 ± 0.3 cm) under drought stress compared to the controls [75]. This enabled the plants to withstand water stress and survive.…”

“…Recent information on the utilization of rhizospheric microorganisms in enhancing soil health and agricultural sustainability has been extensively reviewed [63,[68][69][70][71][72]. PGPR have been utilized in several crops such as garden pea (Pisum sativum L.) [73][74][75], maize (Zea mays) [21,[76][77][78][79], green gram (Vigna radiate L.) [44,52,[80][81][82], cucumber (Cucumis sativus L.) [83], potato (Solanum tuberosum L.) [44,84], sorghum (Sorghum bicolar) [85], wheat (Triticum aestivum) [86][87][88], foxtail millet (Setaria italica L.) [89] and lettuce (Lactuca sativa) [90]. The various mechanisms used by the PGPR for mitigation of water stress in plants are summarized in Table 2.…”

“…The growth of the plants was enhanced by increasing the biomass of the crops four times when compared to the un-inoculated controls, as well as contributed significantly to reduced levels of ethylene in the stressed plants The growth of the plants was enhanced by increasing the biomass of the crops four times over compared to the un-inoculated controls, as well as contributed significantly to reduced levels of ethylene in the stressed plants [101,102]. Since the study of Mayak et al [101], other authors have used ACC deaminase producing PGPR to promote crop production and reduce yield losses in crops exposed to water stress [75,86,89,91,92]. This was documented in a recent study in which Pseudomonas fluorescens DR7 and Pseudomonas fluorescens D11 with high ACC deaminase activities (24.56 ± 2.24 µmol α-KB mg protein −1 h −1 and 39.40 ± 0.68 µmol α-KB mg protein −1 h −1 ) significantly (p < 0.05) enhanced the germination of foxtail millet (13.68%-141.82%) at water potentials of −0.49 MPa and −1.03 Mpa (enhancement of 13.68% and 141.28%), respectively [89].…”

Plant Growth Promoting Rhizobacteria (PGPR) Regulated Phyto and Microbial Beneficial Protein Interactions

“…Some members of this protein family have no eukaryotic existence, but this might have remained in root cells following plant treatment and may play an intrinsic role. This resulted in phytobeneficial traits such as tolerance to salinity [16], heavy metal [1,2], and drought [17], or increased plant biomass under normal environmental conditions [18]. Similarly, the results of SNN, GNN and STRING protein functional networks of sorghum root proteins identified the main protein families: HSP70, MreB_Mbl, StbA and FtsA.…”