Stress-tolerant Plant Growth-Promoting Mesorhizobium ciceri Isolates from MID-gangetic Plains

Chickpea (Cicer arietinum L.) is one of the major sources of dietary protein for the majority of populations in developing countries like India. It also increases soil fertility through its symbiotic nitrogen fixation in association with Mesorhizobium ciceri. In the present study, 40 M. ciceri isolates were recovered from root nodules and the rhizospheric soil of chickpea collected from different chickpea-producing areas of the mid-Gangetic Plains, Uttar Pradesh, India. The isolates were characterized on the basis of biochemical characteristics as well as 16S rDNA sequences. All the isolates were investigated for stress tolerance and plant growth-promoting (PGP) characteristics. M. ciceri isolates have shown wide diversity in their tolerance to high temperatures, salinity and extreme pH. Large numbers of these isolates showed an ability of mineral mobilization, i.e. phosphate (55%) and zinc (42%). Also M. ciceri isolates exhibited PGP characteristics such as production of siderophores (27.5%), ammonia (20%), hydrogen cyanide (10%) and indole acetic acid (5%). Furthermore, a high genetic diversity among the isolates was observed based on the enterobacterial repetitive intergenic consensus-PCR amplified band patterns. In conclusion, these stress-tolerant PGP isolates of M. ciceri may be very crucial for the chickpea production in sustainable agriculture.