Different Cell Wall-Degradation Ability Leads to Tissue-Specificity between Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola

Jianbo Cao,Limin He,Chuanliang Chu,Meng Yuan,Xianghua Li,Meng Zhang,Lihong Qin

doi:10.3390/pathogens9030187

Abstract

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) lead to the devastating rice bacterial diseases and have a very close genetic relationship. There are tissue-specificity differences between Xoo and Xoc, i.e., Xoo only proliferating in xylem vessels and Xoc spreading in intercellular space of mesophyll cell. But there is little known about the determinants of tissue-specificity between Xoo and Xoc. Here we show that Xoc can spread in the intercellular spaces of mesophyll cells to form streak lesions. But Xoo is restricted to growth in the intercellular spaces of mesophyll cells on the inoculation sites. In vivo, Xoc largely breaks the surface and inner structures of cell wall in mesophyll cells in comparison with Xoo. In vitro, Xoc strongly damages the cellulose filter paper in comparison with Xoo. These results suggest that the stronger cell wall-degradation ability of Xoc than that of Xoo may be directly determining the tissue-specificity.

Highlights

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) lead to bacterial blight and bacterial leaf streak in rice (Oryza sativa L.), respectively [1]
The leaves inoculated with Xoo represented water-soaked symptom with little brown color around inoculation sites and the leaves inoculated with Xoc were yellow colored at 5 days after infection (DAI) (Figure 1A)
There were many bacteria around mesophyll cells in leaf inoculated by Xoo and Xoc on inoculation sites (Figure 1B-1,C-3)

Summary

Introduction

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) lead to bacterial blight and bacterial leaf streak in rice (Oryza sativa L.), respectively [1]. Oryzicola (Xoc) lead to bacterial blight and bacterial leaf streak in rice (Oryza sativa L.), respectively [1]. Bacterial blight and bacterial leaf streak are devastating bacterial disease of rice worldwide [1,2]. Xoo and Xoc both belong to Xanthomonas species in the Gammaproteobacteria and have a very close genetic relationship [1,2]. Xoo enters rice leaf through hydathodes or wounds multiplies in xylem vessels to cause leaf blight [1]. Xoc gains access to leaf by stomata or wounds and multiplies in the sub-stomatal cavity [1]. Xoc can spread in the intercellular spaces of mesophyll cells to form streak lesions between the veins [1]. The determinants of Xoo and Xoc parasitic tissue-specificity are still largely unknown [3]

Methods

Results

Conclusion