Physio biochemical and molecular determinants in rhizo bacteria common bean interactions

Abstract

newline This study was conducted to investigate the rhizobacterial and common bean interactions where in roots of Phaseolus vulgaris L. were collected from different regions of Bhadarwah to isolate rhizobacteria from root nodules. The 16S rRNA partial gene sequence of the isolates BR3, BR5 and BR6 showed more than 99 percent similarity with Bacillus megaterium (ROA047), Bacillus aryabhattai (HFBP06) and Bacillus spp. (UFPI-57A), respectively. Eight cultivars/lines were initially screen for nodulation efficiency out of which four cultivars viz. BR 104, VL 125, VL 63 and BR 50 showed greater nodulation efficiency. Two rhizobiumspp.(T1, T2), two rhizobacterial isolates (T3, T4), one combination treatment (Bacillus megaterium + Rhizobium leguminasarum) (T5), one nitrogen treatment (T6) and untreated control was used for greenhouse pot experiments. In most of the parameters studied, T5 treatment and cultivar BR 104 were found to be significantly different for biochemical parameters analysed. The roots of BR 104 contained highest nitrate content (23.02µg/g FW) with T6 treatment while nodules of BR 104 recorded 7.58 µg/g FW with T5 treatment. Similarly, highest root and nodule allantoin content was found in BR 104 in T5. There was constant increase in oxidative stress indices such as ascorbic acid, hydrogen peroxide (H2O2) and lipid peroxidation during nodulation stage. SOD activity on 15th day was maximum in T5 treatment in cultivar BR 50 followed by treatment T5 and T6 in VL 63 and VL 125.On 20th and 30th day. POX activity on 15th and 20th day with T6 was recorded highest in VL 63 (10.03 µM min/mg protein, 16.96 µM/min/mg protein). Semi-quantitative RT-PCR expression of chalconesynthasegene(CHS)studied in cultivarBR 104 under inoculation T1 and T5 was found to be upregulated with time (24 h, 48 h, 72 h, 96 h, 120 h, 144 h and 168 h). Thus, it can be concluded that native rhizobacteria isolate along with rhizobium inoculant can be used to improve the overall growth, symbiotic parameters and enhanced yield of com