The signal orchestration between legumes and the rhizobia attribute to symbiotic nitrogen fixation through nodule formation. Root nodules serve as a nutrient-rich reservoir and harbor diverse microbial communities. However, the existence of non-rhizobial endophytes (NRE) and their role inside the root nodules are being explored; there is no evidence on yeast microflora inhabiting nodule niche. This study focused on unraveling the presence of yeast in the root nodules and their possible function in either nodulation or signal exchange. From the root nodules of blackgram, two yeast strains were isolated and identified as Candida glabrata VYP1 and Candida tropicalis VYW1 based on 18S rRNA gene sequencing and phylogeny. These strains possessed plant growth-promoting traits viz., IAA, ACC deaminase, siderophore, ammonia, and polyamine production. The functional capacity of endophytic yeast strains, and their interaction with Rhizobium sp. was further unveiled via profiling volatile organic compounds (VOC). Among the VOCs, α-glucopyranoside and pyrroloquinoline pitches a pivotal role in activating lectin pathways and phosphorous metabolism. Further, lectin pathways are crucial for nodulating bacterium, and our study showed that these endophytic yeasts assist nodulation by Rhizobium sp. via activating the nod factors. The plant growth-promoting traits of NRE yeast strains coupled with their metabolite production, could recruit them as potential drivers in the plant–microbe interaction.

中文翻译：

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非根瘤菌内生 (NRE) 酵母有助于根瘤菌根瘤中的根瘤菌 (Vigna mungo L.)

豆科植物和根瘤菌之间的信号协调归因于通过根瘤形成进行的共生固氮。根瘤是营养丰富的水库，并拥有多种微生物群落。然而，正在探索非根瘤菌内生菌 (NRE) 的存在及其在根瘤中的作用；没有证据表明酵母菌群栖息在根瘤生态位上。这项研究的重点是解开根瘤中酵母的存在及其在结瘤或信号交换中的可能功能。从blackgram的根瘤中分离出两种酵母菌株，基于18S rRNA基因测序和系统发育鉴定为光滑念珠菌VYP1和热带念珠菌VYW1。这些菌株具有促进植物生长的特性，即 IAA、ACC 脱氨酶、铁载体、氨和多胺生产。内生酵母菌株的功能能力，以及它们与根瘤菌的相互作用。通过分析挥发性有机化合物 (VOC) 进一步揭晓。在 VOC 中，α-吡喃葡萄糖苷和吡咯喹啉在激活凝集素途径和磷代谢方面发挥着关键作用。此外，凝集素途径对于结瘤细菌至关重要，我们的研究表明，这些内生酵母有助于根瘤菌的结瘤。通过激活点头因子。NRE 酵母菌株的植物生长促进特性与其代谢产物的产生相结合，可以将它们作为植物-微生物相互作用的潜在驱动因素。α-吡喃葡萄糖苷和吡咯喹啉在激活凝集素途径和磷代谢方面发挥着关键作用。此外，凝集素途径对于结瘤细菌至关重要，我们的研究表明，这些内生酵母有助于根瘤菌的结瘤。通过激活点头因子。NRE 酵母菌株的植物生长促进特性与其代谢产物的产生相结合，可以将它们作为植物-微生物相互作用的潜在驱动因素。α-吡喃葡萄糖苷和吡咯喹啉在激活凝集素途径和磷代谢方面发挥着关键作用。此外，凝集素途径对于结瘤细菌至关重要，我们的研究表明，这些内生酵母有助于根瘤菌的结瘤。通过激活点头因子。NRE 酵母菌株的植物生长促进特性与其代谢产物的产生相结合，可以将它们作为植物-微生物相互作用的潜在驱动因素。