Department of Forestry, Nanjing Forestry University, Nanjing 210037, China.
Department of Biology and Environment, Nanjing Forestry University, Nanjing 210037, China.
Int J Mol Sci. 2023 Sep 19;24(18):14282. doi: 10.3390/ijms241814282.
The research on plant endophytes has been drawing a lot of attention in recent years. belongs to a group of endophytes with plant growth-promoting activity and has been widely used in agricultural fields. In our earlier studies, FBS135 was isolated from healthy-growing and was able to promote pine growth. FBS135 can grow under extremely low nitrogen conditions. To understand the mechanism of the low-nitrogen tolerance of this bacterium, the transcriptome of FBS135 in the absence of nitrogen was examined in this study. We found that FBS135 actively regulates its gene expression in response to nitrogen deficiency. Nearly half of the number (4475) of genes in FBS135 were differentially expressed under this condition, mostly downregulated, while it significantly upregulated many transportation-associated genes and some nitrogen metabolism-related genes. In the downregulated genes, the ribosome pathway-related ones were significantly enriched. Meanwhile, we constructed a Tn5 transposon library of FBS135, from which four genes involved in low-nitrogen tolerance were screened out, including the gene for the host-specific protein J, RNA polymerase σ factor RpoS, phosphoribosamine-glycine ligase, and serine acetyltransferase. Functional analysis of the genes revealed their potential roles in the adaptation to nitrogen limitation. The results obtained in this work shed light on the mechanism of endophytes represented by FBS135, at the overall transcriptional level, to an environmentally limited nitrogen supply and provided a basis for further investigation on this topic.
近年来，植物内生菌的研究受到了广泛关注。属于具有植物生长促进活性的内生菌群，已广泛应用于农业领域。在我们早期的研究中，从健康生长的 中分离出了 FBS135，它能够促进松树生长。FBS135 可以在极低氮条件下生长。为了了解该细菌耐低氮的机制，本研究检测了 FBS135 在缺乏氮源时的转录组。我们发现 FBS135 积极调节其基因表达以应对氮缺乏。在这种条件下，FBS135 中近一半（4475 个）的基因表达差异，大多数下调，而它显著上调了许多与运输相关的基因和一些与氮代谢相关的基因。在下调的基因中，核糖体途径相关基因显著富集。同时，我们构建了 FBS135 的 Tn5 转座子文库，从中筛选出了四个参与耐低氮的基因，包括宿主特异性蛋白 J 的基因、RNA 聚合酶 σ 因子 RpoS、磷酸核糖胺-甘氨酸连接酶和丝氨酸乙酰转移酶。基因的功能分析揭示了它们在适应氮限制方面的潜在作用。本工作的结果阐明了以 FBS135 为代表的内生菌在整体转录水平上适应环境有限氮供应的机制，为进一步研究这一课题提供了依据。
