β‑Glucanase Family Genes Promote Resistance to Sheath Blight in Rice by Inhibiting the Permeability of Plasmodesmata

Rice
sheath blight (ShB) caused by Rhizoctonia solani is one of the most serious diseases that threatens rice (Oryza sativa) production. However, the mechanisms
of defense against ShB in rice remain largely unknown. In this study,
we identified that the expression levels of β-glucanase (OsBGL) family genes sensitively respond to infection
by R. solani, and OsBGLs positively regulate rice resistance to ShB. In addition, OsBGL2 colocalized with AtPDCB1 at the plasmodesmata (PD)
and limited the PD permeability. The level of callose accumulation
in osbgls mutants and overexpressors was examined,
and OsBGLs were found contribute to callose accumulation.
Taken together, these data suggest that OsBGLs can
regulate the deposition of callose at the PD to reduce its permeability
to defend itself against ShB. Through the identification of these
genes and the elucidation of their functions, this research fills
the gap in the mechanism of PD permeability in rice ShB resistance.