Cross-climatic comparison of microbial stress-responsive genes in urban parks: A comparative analysis

Understanding the distribution and abundance of microbial stress-related genes (SRGs) is crucial for unraveling the intricate dynamics of microbial communities and their responses to diverse environmental conditions. Despite the importance of these genes in shaping microbial adaptation and resilience, a comprehensive examination of their relative abundance across distinct climatic regions, such as boreal, temperate, and tropical environments, remains notably scarce in the existing literature. This study seeks to address this research gap by exploring and comparing the relative abundances of microbial SRGs using GeoChip 5.0 functional gene array in these three climatic regions. Our data indicate a greater relative abundance of SRGs such as nsrR, degP, cpxR, ahpF, Obg and cisD in the tropical region than in the other two regions whereas ecf and glnA showed higher abundance in both temperate and tropical regions in terms of reference forests and old parks. The distinct characteristics of the tropical biome are likely to influence both SRGs and the profile of SRG-hosts, consequently enhancing soil microbial abundances. Moreover, multivariate analyses unveiled distinct SRG profiles in urban parks and climatic regions. Additionally, we explored the influence of plant functional types (recalcitrant and labile tree litter, lawn) on SRGs. The impact of vegetation type on SRGs was not statistically significant, except in the tropical region, where its influence was notably pronounced compared to the boreal and temperate regions. Furthermore, several genes (nsrR, degP, cpxR, degS, dnaK, Obg, cisD, and glnA) were more prevalent in old parks when compared to young parks in all three climatic regions. However, urban parks displayed a significantly elevated abundance of SRGs compared to forest areas. This study provides new insights into the prevalence of SRGs across different climatic regions, enhancing our understanding of their dynamics in both human-influenced environments and pristine habitats.