Involvement of type VI secretion system in secretion of iron chelator pyoverdine in Pseudomonas taiwanensis.
Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an iron chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo. Through Tn5 mutagenesis of P. taiwanensis, we showed that mutations in genes that encode components of the type VI secretion system (T6SS) as well as biosynthesis and maturation of pyoverdine resulted in reduced toxicity against Xoo. Our results indicated that T6SS is involved in the secretion of endogenous pyoverdine. Mutations in T6SS component genes affected the secretion of mature pyoverdine from the periplasmic space into the extracellular medium after pyoverdine precursor is transferred to the periplasm by the inner membrane transporter PvdE. In addition, we also showed that other export systems, i.e., the PvdRT-OpmQ and MexAB-OprM efflux systems (for which there have been previous suggestions of involvement) and the type II secretion system (T2SS), are not involved in pyoverdine secretion.
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.|Institute of Biotechnology, National Taiwan University, Taipei, 10617, Taiwan.
Wen-Jen
WJ
Chen
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.
Tzu-Yen
TY
Kuo
Biopesticide Division, Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Council of Agriculture, Taichung, 41358, Taiwan.
Feng-Chia
FC
Hsieh
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.
Pi-Yu
PY
Chen
Department of Agronomy, National Chung Hsing University, Taichung, 40227, Taiwan.
Chang-Sheng
CS
Wang
Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan.
Yu-Ling
YL
Shih
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.
Ying-Mi
YM
Lai
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.|Institute of Biotechnology, National Taiwan University, Taipei, 10617, Taiwan.
Je-Ruei
JR
Liu
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.
Yu-Liang
YL
Yang
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan.|Institute of Biotechnology, National Taiwan University, Taipei, 10617, Taiwan.
Ming-Che
MC
Shih
D061046:Biological Control Agents; D005798:Genes, Bacterial; D007502:Iron Chelating Agents / Q000378:metabolism*; D016296:Mutagenesis; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D011549:Pseudomonas / Q000235:genetics / Q000378:metabolism*; D017262:Siderophores / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000069376:Type VI Secretion Systems / Q000235:genetics / Q000378:metabolism*; D014974:Xanthomonas / Q000472:pathogenicity
D061046:Biological Control Agents; D007502:Iron Chelating Agents; D009842:Oligopeptides; D017262:Siderophores; D000069376:Type VI Secretion Systems; C042453:pyoverdin