Alleviation of salinity stress in faba bean (Vicia faba L.) plants by inoculation with plant growth promoting rhizobacteria (PGPR)

The effects of three bacterial isolates ('Pseudomonas putida', 'P. fluorescens' and 'Bacillus subtilis') of plant growth promoting rhizobacteria were investigated to improve the growth of six cultivars from 'Vicia faba' L. under two levels of salinity stress (S1=4000 and S2=8000 ppm). Different morphological and biochemical parameters were studies. The highest values of final germination percent were observed in cultivar Wadi 1 and Line 1 (96%) in the presence of 'P. fluorescens'. Application of 'P. putida' decreased the mean germination time in the presence or absent salinity stress. The salinity treatments induced a significant decreased in all of plant growth parameters, plant chlorophyll and plant soluable proteins, while plant proline was increased, comparing to control. The plants treated with 'P. fluorescens' showed significant increase in growth traits such as plant length (10.66%), plant shoot fresh weight (9.52%) and plant leaf area (61.86%). This increasing trend was followed by application of 'B. subtilis' then 'P. putida'. The phylogenetic diversity relationship and the level of genetic diversity among the cultivars were assessed using 9 arbitrary primers. The results indicated that 6 out of the 9 primers [(GATA)4GC, (AGAC)4GC, GAC(GATA)4, (AC)8YC, CGC(GATA)4 and (AG)8YC] can generate clear multiplex banding profiles. Among the 48 polymorphism bands, only 14 were found to be useful as positive or negative markers related to salt stress. The cluster analysis classified the cultivars into two main groups. The inter-simple sequence repeat can be used to identify alleles associated with the salt stress in faba bean germplasm.