Generational\nSpecific Recruitment of Arsenic- and\nAntimony-Reducing Microorganisms in Plant Root-Associated Niches for\nAdapting to Metalloid-Metal Pollution

The\nrecruitment of microorganisms by plants can enhance their adaptability\nto environmental stressors, but how root-associated niches recruit\nspecific microorganisms for adapting to metalloid-metal contamination\nis not well-understood. This study investigated the generational recruitment\nof microorganisms in different root niches of Vetiveria\nzizanioides (V. zizanioides) under arsenic (As) and antimony (Sb) stress. The V. zizanioides was cultivated in As- and Sb-cocontaminated\nmine soils (MS) and artificial pollution soils (PS) over two generations\nin controlled conditions. The root-associated microbial communities\nwere analyzed through 16S rRNA, <i>arsC</i>, and <i>aioA</i> gene amplicon and metagenomics sequencing. V. zizanioides accumulated higher As(III) and Sb(III)\nin its endosphere in MS in the second generation, while its physiological\nindices in MS were better than those observed in PS. SourceTracker\nanalysis revealed that V. zizanioides in MS recruited As(V)- and Sb(V)-reducing microorganisms (e.g., <i>Sphingomonales</i> and <i>Rhodospirillaceae</i>) into\nthe rhizoplane and endosphere. Metagenomics analysis further confirmed\nthat these recruited microorganisms carrying genes encoding arsenate\nreductases with diverse carbohydrate degradation abilities were enriched\nin the rhizoplane and endosphere, suggesting their potential to reduce\nAs(V) and Sb(V) and to decompose root exudates (e.g., xylan and starch).\nThese findings reveal that V. zizanioides selectively recruits As- and Sb-reducing microorganisms to mitigate\nAs–Sb cocontamination during the generational growth, providing\ninsights into novel strategies for enhancing phytoremediation of metalloid-metal\ncontaminants.