Table_1_Phosphate-Solubilizing Pseudomonas sp. Strain WS32 Rhizosphere Colonization-Induced Expression Changes in Wheat Roots.docx

Rhizosphere colonization is a pre-requisite for the favorable application of plant growth-promoting rhizobacteria (PGPR). Exchange and mutual recognition of signaling molecules occur frequently between plants and microbes. Here, the luciferase luxAB gene was electrotransformed into the phosphate-solubilizing strain Pseudomonas sp. WS32, a type of plant growth-promoting rhizobacterium with specific affinity for wheat. A labeled WS32 strain (WS32-L) was applied to determine the temporal and spatial traits of colonization within the wheat rhizosphere using rhizoboxes experimentation under natural condition. The effects of colonization on wheat root development and seedling growth were evaluated, and RNA sequencing (RNA-seq) was performed to explore the transcriptional changes that occur in wheat roots under WS32 colonization. The results showed that WS32-L could survive in the wheat rhizosphere for long periods and could expand into new zones following wheat root extension. Significant increases in seedling fresh and dry weight, root fresh and dry weight, root surface area, number of root tips, and phosphorus accumulation in the wheat leaves occurred in response to WS32 rhizosphere colonization. RNA-seq analysis showed that a total of 1485 genes in wheat roots were differentially expressed between the inoculated conditions and the uninoculated conditions. Most of the transcriptional changes occurred for genes annotated to the following functional categories: “phosphorus and other nutrient transport,” “hormone metabolism and organic acid secretion,” “flavonoid signal recognition,” “membrane transport,” and “transcription factor regulation.” These results are therefore valuable to future studies focused on the molecular mechanisms underlying the growth-promoting activities of PGPR on their host plants.根际定殖是植物促生根际菌（Plant Growth-Promoting Rhizobacteria, PGPR）得以有效应用的前提条件。植物与微生物之间频繁发生信号分子的交换与相互识别过程。本研究将荧光素酶luxAB基因通过电转化法导入溶磷假单胞菌（Pseudomonas sp.）WS32菌株中，该菌株是一类对小麦具有特异亲和性的植物促生根际菌。随后利用标记得到的WS32菌株（WS32-L），通过自然条件下的根箱实验，探究其在小麦根际内的定殖时空特征。本研究同时评估了该菌株定殖对小麦根系发育及幼苗生长的影响，并通过RNA测序（RNA-seq）分析WS32定殖后小麦根系的转录组变化。结果表明，WS32-L可在小麦根际中长期存活，并伴随小麦根系伸长而向新区域拓殖。经WS32根际定殖后，小麦幼苗的鲜重、干重，根系鲜重、干重、根表面积、根尖数量以及叶片磷积累量均显著提升。RNA-seq分析显示，接种组与未接种组的小麦根系中共鉴定出1485个差异表达基因。大部分差异表达基因被注释到以下功能类别：“磷及其他养分转运”、“激素代谢与有机酸分泌”、“类黄酮信号识别”、“膜转运”以及“转录因子调控”。上述研究结果可为后续解析PGPR对宿主植物的促生活性分子机制提供重要参考依据。