Combinative effects of a bacterial type-III effector and a biocontrol bacterium on rice growth and disease resistance

Journal of biosciences

Haiying Ren¹  Juying Long¹  Tao Song¹  Qian Yin¹  Tingquan Wu¹  Ganyu Gu¹  Shujian Zhang¹  Hansong Dong1¹  Zhiyi Chen² 

[1] Key Laboratory of Monitoring and Management of Plant Pathogens and Insect Pests, Ministry of Agriculture of China, and Department of Plant Pathology, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, China$$;Institute of Plant Protection, Jiangsu-Provincial Academy of Agricultural Sciences, 1 Zhongling Street, Nanjing, 210014, China$$

关键词: Biocontrol bacteria;    disease resistance;    growth promotion;    hpa 𝐺Xoo-expressing rice line 1 (HER1);    rice;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Expression of HpaGXoo, a bacterial type-III effector, in transgenic plants induces disease resistance. Resistance also can be elicited by biocontrol bacteria. In both cases, plant growth is often promoted. Here we address whether biocontrol bacteria and HpaGXoo can act together to provide better results in crop improvement. We studied effects of Pseudomonas cepacia on the rice variety R109 and the hpaGXoo-expressing rice line HER1. Compared to R109, HER1 showed increased growth, grain yield, and defense responses toward diseases and salinity stress. Colonization of roots by P. cepacia caused 20% and 13% increase, in contrast to controls, in root growth of R109 and HER1. Growth of leaves and stems also increased in R109 but that of HER1 was inhibited. When P. cepacia colonization was subsequent to plant inoculation with Rhizoctonia solani, a pathogen that causes sheath blight, the disease was less severe than controls in both R109 and HER1; HER1, nevertheless, was more resistant, suggesting that P. cepacia and HpaGXoo cooperate in inducing disease resistance. Several genes that critically regulate growth and defense behaved differentially in HER1 and R109 while responding to P. cepacia. In R109 leaves, the OsARF1 gene, which regulates plant growth, was expressed in consistence with growth promotion by P. cepacia. Inversely, OsARF1 expression was coincident with inhibition in growth of HER1 leaves. In both plants, the expression of OsEXP1, which encodes an expansin protein involved in plant growth, was concomitant with growth promotion in leaves instead of roots, in response to P. cepacia. We also studied OsMAPK, a gene that encodes a mitogen-activated protein kinase and controls defense responses toward salinity and infection by pathogens in rice. In response to P. cepacia, an early expression of OsMAPK was coincident with R109 resistance to the disease, while HER1 expressed the gene similarly whether P. cepacia was present or not. Evidently, P. cepacia and GXoo-gene mediated resistance may act differently in rice growth and resistance. Whereas combinative effects of P. cepacia and HpaGXoo in disease resistance have a great potential in agricultural use, it is interesting to study mechanisms that underlie interactions involving biocontrol bacteria, type-III effectors and pathogens.

【 授权许可】

Unknown