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

Abstract

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.

A computational model of Pseudomonas syringae metabolism unveils a role for branched-chain amino acids in Arabidopsis leaf colonization

“…In the plant pathogen Erwinia amylovora , Lrp is necessary to express virulence genes that control motility and synthesis of exopolysaccharides, a function that becomes apparent when BCAA levels are low [ 46 ]. Similarly, in the corn pathogen Pantoea stewartia , Lrp is necessary to induce disease symptoms in the plant, indicative of successful virulence expression [ 48 ]. The evidence contributed by Tomassetti et al [ 45 ], Schachterle and Sundin [ 46 ], and Bartholomew et al [ 48 ] suggest that leucine degradation, and more broadly, BCAAs degradation, plays a positive role in virulence induction by lowering intracellular levels of BCAAs and allowing Lrp to transcribe virulence genes.…”

“…Similarly, in the corn pathogen Pantoea stewartia , Lrp is necessary to induce disease symptoms in the plant, indicative of successful virulence expression [ 48 ]. The evidence contributed by Tomassetti et al [ 45 ], Schachterle and Sundin [ 46 ], and Bartholomew et al [ 48 ] suggest that leucine degradation, and more broadly, BCAAs degradation, plays a positive role in virulence induction by lowering intracellular levels of BCAAs and allowing Lrp to transcribe virulence genes. The molecular mechanisms by which BCAAs impact gene expression in Pst DC3000 remain unknown.…”

“…To create a carbon utilization list for AMMEDEUS, we performed SCS growth phenotyping using Biolog phenotype microarrays PM1 and PM2a plates (Hayward, CA). We grew Pst DC3000 in each of 190 SCS in quadruplicate and recorded the optical density at 600nm (OD600) at 0, 12,24,36,48,and 60 hours (Fig 1B and S1 Dataset). To only include high-confidence growth conditions for gap-filling, we only considered conditions that resulted in a max OD600 greater than 0.3 after subtracting the 0-hour baseline.…”

Biofilm-Forming Ability of Phytopathogenic Bacteria: A Review of its Involvement in Plant Stress

“…The water flow is blocked and symptoms appear, ranging from chlorotic lesions on leaves that eventually become necrotic and delay growth to rapid wilting and death in more susceptible plants. Stewartan also facilitates the pathogen's movement through the vessels or intercellular spaces, which increases virulence [114,122,124,125].…”

Status and Recent Developments of Pantoea stewartii subsp. stewartii Causes the Wilt Disease in Maize in Indonesia: A Review

“…The control function of two transcription factors, Lrp and IscR, is important for P. stewartii. These two transcription factors affect the colonization process, growth in maize and their effect on host growth (Bartholomew et al, 2022). De Maayer et al (2011 reported that the pantoea genus also involves VgrG and Hcp proteins which indirectly involve the type IV secretion system.…”