[Distribution Characteristics of Soil Resistance Genes in Cotton Fields with Different Continuous Cropping Years].

Abstract

With the continuous development of intensive agriculture， the crop rotation index has increased. Continuous planting of a single type of crop introduces specific environmental selective pressures that may lead to changes in the soil resistome. Therefore， investigating the composition and characteristics of antibiotic resistance genes （ARGs） and metal resistance genes （MRGs） in soil with different degrees of continuous cropping is of great significance for promoting the green development of agriculture. In this study， we employed metagenomics techniques to examine the profile of ARGs in cotton field soils across different levels of continuous cropping years in the Xinjiang Arid Region. Our findings revealed that the types and abundance of ARGs and MRGs in cotton field soils differed with the length of continuous cropping periods. A total of 1 181 ARGs and 506 MRGs were found in the present study. Continuous cropping led to the emergence of some new ARGs and MRGs. Network and Procrustes analysis indicated a significant correlation between the composition of ARGs and MRGs. Additionally， the actP gene was the key node connecting ARGs and MRGs. Mantel tests demonstrated that ARGs and MRGs were not correlated with soil pH， alkali-hydrolyzable nitrogen， total nitrogen， or total potassium levels. However， a strong positive correlation was observed between these genes and soil electrical conductivity （Mantels' P=0.001） and a significant but weak correlation with the continuous cropping years （Mantels' P < 0.05）.