Screening of indigenous endophytic diversity of Chickpea for multifunctional PGP traits under changing climatic conditions

Abstract

The present investigation was carried out to exploit diverse endophytic bacteria from Chickpea. 65 endophytic bacteria were isolated from different tissue samples (leaf, stem, root, and nodules) of Chickpeas. All were tested for IAA production, phosphate, and zinc solubilization. Maximum growth response for salt tolerance was observed in isolate CCN2 (0.95) followed by NKS2 (0.90) at a salinity level of 8 dS m⁻¹. Similarly, in the drought tolerance, maximum growth was recorded with CKN3 followed by NKN2 at 7.5 % PEG-6000 concentration. Significantly high (p < 0.05) production of IAA was shown by root endophytic Pseudomonas sp. PCR4 (65.98 μg ml⁻¹) followed by Bacillus sp. NCR3 (60.90 μg ml⁻¹). Significantly, high P-solubilization was observed in Bacillus sp. NKL4 (18.26 μg ml⁻¹) followed by Pseudomonas sp. PCS3 (16.94 μg ml⁻¹). Pseudomonas sp. (PCS-1) possesses the highest zinc solubilization index for zinc phosphate (2.34), whereas the zinc carbonate solubilization index was highest in Rhizobium sp. CCN4 (2.3). Out of 65 endophytic bacteria isolates, 47.69 %, 44.61 %, 15.38 %, and 66.66 % produced cellulase, protease enzymes, HCN, and fluorescence pigmentation, respectively. Maximum percent growth inhibition was recorded with Pseudomonas sp. (67.80 %) followed by Pseudomonas sp. (53.57 %) against Fusarium oxysporum. Out of 65, five endophytic bacterial isolates were selected based on multifunctional PGP traits, salt, drought tolerance, and antagonistic activities for traditional bioassays for triple response. The Bacillus sp. NKL2 and NKL1 produced the highest total fresh weight (1.55 and 1.42 folds), total dry matter (1.93 and 1.81 folds), and salt tolerance index (1.94 and 1.81) in the conventional triple response bioassay compared to the uninoculated control at the 8 dS m⁻¹ salinity level. This study showed that three Bacillus spp. (NKL2, NKL1 and NCS1), one Pseudomonas spp. (PCS1) and one Rhizobium spp. (CCN4) were most promising according to PGP characteristics, stress tolerance, antagonistic activities, and classical triple cross-test assay. Therefore, considering such salt-tolerant, mineral-solubilizing potential indigenous endophytic bacterial isolates for producing bio-inoculants could be an eco-friendly innovation for climate-smart agriculture under abiotic and biotic stress challenges.