Long-term fertilisation management changes bacterial phoD and gcd gene communities and abundances in the rhizosphere of cotton (Gossypium hirsutum L.) grown in a grey desert soil

Exploring the genetic potential of soil functional microbes to solubilise and mineralise recalcitrant inorganic and organic P is an important step towards an improved understanding of the fundamental mechanisms driving soil P cycling and optimising P fertilisation management. However, studies on the key genes of functional microbes to P transformation remains largely unknown. It is necessary to assess their roles and contributions to further understand the microbial regulatory mechanism of the P-cycling process. In the present study, the effects of longterm fertilisation on the phoD- and gcd-harbouring bacterial communities in the cotton rhizosphere at the bud stage were investigated using high-throughput sequencing technology. The phoD- and gcd-harbouring bacterial community structures in the cotton rhizosphere changed significantly in response to long-term fertilisation regimes. Pseudomonas and Sinorhizobium were the dominant genera shared by the phoD- and gcd-harbouring bacterial community composition. The abundant genera Pseudomonas and Mesorhizobium in the phoD-harbouring bacteria, and Planctomyces, Lacunisphaera and Amycolatopsis in the gcd-harbouring bacteria were observed as members of keystone species in the community network, respectively. Significant correlations were detected between soil available P and the phoD-harbouring Mesorhizobium and Aurantimonas, and gcd-harbouring Planctomyces and Lacunisphaera. Moreover, the soil available P was significantly and negatively correlated with abundance of phoD and gcd genes. These results have demonstrated that the composition and abundance of phoD and gcd genes are governed by soil-available P drivers and provide new insights into the roles of functional microbes involved in soil recalcitrant P mobilisation and optimal management of P fertiliser.