Data_Sheet_1_The Transcription Factor Lrp of Pantoea stewartii subsp. stewartii Controls Capsule Production, Motility, and Virulence Important for in planta Growth.docx

The bacterial phytopathogen Pantoea stewartii subsp. stewartii causes leaf blight and Stewart’s wilt disease in susceptible corn varieties. A previous RNA-Seq study examined P. stewartii gene expression patterns during late-stage infection in the xylem, and a Tn-Seq study using a P. stewartii mutant library revealed genes essential for colonization of the xylem. Based on these findings, strains with in-frame chromosomal deletions in the genes encoding seven transcription factors (NsrR, IscR, Nac, Lrp, DSJ_00125, DSJ_03645, and DSJ_18135) and one hypothetical protein (DSJ_21690) were constructed to further evaluate the role of the encoded gene products during in vitro and in planta growth. Assays for capsule production and motility indicate that Lrp plays a role in regulating these two key physiological outputs in vitro. Single infections of each deletion strain into the xylem of corn seedlings determined that Lrp plays a significant role in P. stewartii virulence. In planta xylem competition assays between co-inoculated deletion and the corresponding complementation or wild-type strains as well as in vitro growth curves determined that Lrp controls functions important for P. stewartii colonization and growth in corn plants, whereas IscR may have a more generalized impact on growth. Defining the role of essential transcription factors, such as Lrp, during in planta growth will enable modeling of key components of the P. stewartii regulatory network utilized during growth in corn plants.

细菌性植物病原菌潘托伊亚·斯图亚特亚种斯图亚特亚种可引发易感玉米品种的叶片褐变和斯图亚特萎蔫病。前期通过RNA-Seq研究对潘托伊亚·斯图亚特亚种在木质部晚期感染期间的基因表达模式进行了考察，而利用潘托伊亚·斯图亚特亚种突变库进行的Tn-Seq研究则揭示了木质部定殖所必需的基因。基于这些发现，构建了七个转录因子（NsrR、IscR、Nac、Lrp、DSJ_00125、DSJ_03645和DSJ_18135）和一个假定的蛋白质（DSJ_21690）的编码基因中具有框架内染色体缺失的菌株，以及一个假定的蛋白质（DSJ_21690）的编码基因中具有框架内染色体缺失的菌株，以进一步评估编码基因产物在体外和植物体内的生长过程中所起的作用。针对荚膜生成和游走能力的检测表明，Lrp在体外调节这两种关键的生理输出中发挥作用。将每个缺失菌株单独感染玉米幼苗的木质部，结果表明Lrp在潘托伊亚·斯图亚特亚种的致病性中起着重要作用。通过共接种缺失菌株与相应的互补或野生型菌株之间的植体内木质部竞争实验以及体外生长曲线分析，确定Lrp控制着对潘托伊亚·斯图亚特亚种在玉米植株中定殖和生长至关重要的功能，而IscR可能对生长具有更广泛的影响。界定如Lrp等关键转录因子在植体内生长过程中的作用，将有助于模拟潘托伊亚·斯图亚特亚种在玉米植株生长过程中所利用的调控网络的关键组成部分。