Ca2+-responsive phospholipid-binding BONZAI genes confer a novel role for cotton resistance to Verticillium wilt

Abstract

Verticillium wilt which produced by the soil-borne fungus Verticillium dahliae is an important biotic threat that limits cotton (Gossypium hirsutum) growth and agricultural productivity. It is very essential to explore new genes for the generation of V. dahliae resistance or tolerance cotton varieties. Ca2+ signaling as a secondary messenger is involved in pathogen stress response. Despite Ca2+-responsive phospholipid-binding BONZAI (BON) genes have intensively been investigated in Arabidopsis, their function has not still been characterized in cotton. Here, we show that three copies of GhBON1, two copies of GhBON2 and GhBON3 were found from the genome sequences of upland cotton. The expression of GhBON1 is inducible to both V. dahliae and salicylic acid (SA), jasmonic acid (JA) and H2O2 stresses. Knocking down of GhBON1, GhBON2 and GhBON3 using virus induced gene silencing (VIGS) each increases up-regulation of defense responses in cotton. These GhBON1, GhBON2 and GhBON3-silenced plants enhance resistance to V. dahliae accompanied by higher burst of hydrogen peroxide and increased cell death and have more effect on the up-regulation of defense response genes. Further analysis revealed that GhBON1 could interacts with BAK1-interacting receptor-like kinase 1 (GhBIR1) and pathogen-associated molecular pattern (PAMP) receptor regulator BAK1 (GhBAK1) at plasma membrane. Our study further reveals that plant Ca2+-responsive phospholipid-binding BONZAI genes negatively regulate Verticillium wilt with the conserved function in response to disease resistance or plant immunity.