Assessment of microbial diversity in the rhizosphere of Pinus roxburghii (Sarg.) and bio-inoculant potential of selected pine bacterial isolates for wheat varieties based on cultureindependent and culture-dependent techniques.

Abstract

Evidence is lacking regarding compatibility of pine bacteria as bio-inoculants for crops. The diversity and abundance of rhizosphere bacteria of Pinus roxburghii has never been investigated with simultaneous application of culture-dependent and culture-independent techniques. The present study was aimed to isolate, characterise, check the bio-inoculant potential of pine bacteria and assess rhizosphere bacterial diversity using culture-independent advanced approaches. Forty bacteria isolated from the rhizoplane of P.roxburghii growing in a cold climate at high altitude in Murree, were morphologically characterised; nine were identified by 16S rRNA sequence analyses and used in experiments. Diversity and abundance of the 16S rRNA gene and nifH gene in the rhizosphere was assessed by cloning, RFLP analysis, 454-amplicon pyrosequencing and qPCR. The bacterial isolates significantly improved dry weight of shoot, root, root area, IAA and GA3 content, number of grains plant-1 , weight of grains plant-1 in wheat varieties Chakwal-50 and Fareed-06 under axenic and field conditions. The number of 16S rRNA sequences (2979) identified by pyrosequencing shared similarity with 13 phyla of bacteria and archaea. The results confirm the existence of diverse bacteria of agricultural and industrial importance in the rhizosphere and compatibility of rhizoplane bacteria as bio-inoculants for wheat varieties.