Rice copine genes OsBON1 and OsBON3 function as suppressors of broad-spectrum disease resistance

Breeding for disease resistance is the most effective strategy to control diseases, particularly with broad-spectrum disease resistance (广谱抗病性) in many crops. However, knowledge on genes and mechanism of broad-spectrum resistance and trade-off (权衡) between defence and growth in crops is limited. Here, we show that the rice copine genes OsBON1 and OsBON3 are critical suppressors of immunity. Both OsBON1 and OsBON3 changed their protein subcellular localization upon pathogen challenge. Knockdown of OsBON1 and dominant negative mutant (显性负性突变体) of OsBON3 each enhanced resistance to rice bacterial and fungal pathogens with either hemibiotrophic (半活体的) or necrotrophic (死体营养的) lifestyles. The defence activation in OsBON1 knockdown mutants was associated with reduced growth, both of which were largely suppressed under high temperature. In contrast, overexpression of OsBON1 or OsBON3 decreased disease resistance and promoted plant growth. However, neither OsBON1 nor OsBON3 could rescue the dwarf phenotype of the Arabidopsis BON1 knockout mutant, suggesting a divergence of the rice and Arabidopsis copine genes. Our study therefore shows that the rice copine genes play a negative role in regulating disease resistance and their expression level and protein location likely have a large impact on the balance between immunity and agronomic traits.

疾病抗性育种是控制疾病的最有效的策略，尤其是作物中的广谱抗病性。然而，目前对于控制广谱抗病性的基因和分子机制以及抗性与生长之间的权衡取舍等方面的理解仍然还有所限制。本文的研究结果揭示了水稻copine基因OsBON1和OsBON3是重要的免疫抑制子。在病原菌侵染时，OsBON1和OsBON3蛋白均会改变其亚细胞定位的位置。敲除OsBON1基因或是OsBON3基因的显性负性突变体均显著增强了水稻对于病毒和半活体或是死体营养方式的真菌病害的抗性。OsBON1基因敲除突变体的抗性激活与生长的衰弱相关，这两者均在高温下被抑制。相反，过表达OsBON1或是OsBON3基因均能减弱水稻的疾病抗性，并促进水稻生长。然而，无论是OsBON1基因或是OsBON3基因均不能拯救拟南芥中的敲除BON1突变体的矮化表型，表明水稻和拟南芥copine基因存在功能分化。本文的研究显示水稻copine基因在调控植物疾病抗性中扮演负向的作用，copine基因的表达及蛋白的定位可能对于水稻免疫和农艺性状的平衡均有比较大的影响。

通讯：何祖华 (http://www.sippe.ac.cn/cp1-8_PI.asp?id=13)

个人简介：1993-1996年，浙江大学生物技术研究所，植物分子生物学和植物病理学博士；1997-1998年，美国加州Salk研究所，植物细胞和分子生物学实验室博士后；1999-2000年，加大Davis分校，植物病理系博士后。

研究方向：植物抗病信号转导、功能基因和信号途径互作。实验室网站：http://sippe.ac.cn/zuhuahe/

doi: 10.1111/pbi.12890