Small G Protein StRab5b positively regulates potato resistance to Phytophthora infestans

Zaimin Tian, Zhiwei Zhang, Liru Kang, Min Li, Jian Zhang, Yan Feng, Jiang Yin, Xuechen Gong, Jun Zhao

Front Plant Sci.; 2023 Jan 9; 13:1065627. doi: 10.3389/fpls.2022.1065627.

Figure: Potato Phytophthora infestans infection symptom.

Abstract

Rabproteins are the largest members of the small G protein family and are widely distributed in eukaryotes. It comprises eight subfamilies and is responsible for regulating vesicle transport, plant growth and development, and biotic and abiotic stress responses. In this study, the small G protein gene StRab5b was cloned from potato, and its biological information, expression profile and induced expression level, overexpression and gene silencing were examined on regulating potato resistance to Phytophthora infestans using PCR, qPCR and Virus-induced gene silencing (VIGS). Our results indicate that the amino acid of StRab5b shows the highest and lowest homology with NbRab5b in N. benthamiana and StRab in potato respectively. StRab5b expression varied among different potato tissues and varieties, and was induced by P. infestans infection. Transiently ectopic expression of StRab5b in N. benthamiana enhanced its resistance to P. infestans, whereas, silencing of StRab5b and its homologous gene facilitated pathogen infection in potato and N. benthamiana respectively. Furthermore, stable expression of the StRab5b gene in potatoes enhanced its redox-stress response capacity, as manifested by the accumulation of H₂O₂ in infected leaves and subsequent increase in the activity and expression of ROS scavenging enzymes, thereby attenuating the development of P. infestans and ultimately reducing the lesions on infected potato leaves. In addition, the LOX gene transcripts and JA level were upregulated rapidly after inoculation with P. infestans. Collectively, our results suggest that StRab5b positively regulates the resistance against potato late blight (PLB) via JA-mediated defense signaling pathway.

See https://pubmed.ncbi.nlm.nih.gov/36699835/

Figure 1

Conservative domain and phylogenetic tree analysis of StRab5b (A) The conserved domains of StRab5b. (B) Phylogenetic tree of StRab5b. The phylogenetic tree was constructed with DNAMAN v. 6.0. The accession number of each protein is as follows: Oryza sativa (AF323991), Nicotiana benthamiana (DQ335217), Solanum tuberosum (ABK96799 and AK323357), Hevea brasiliensis (KC577146), Physcomitrella patens (AB379973), Phoenix dactylifera (AK287492), Nicotiana sylvestris (X63875), Mangifera indica (KF768563), Arabidopsis thaliana (D89824), Selaginella moellendorffii (KF516567), Medicago sativa (X79278), Triticum aestivum (X59133), Lotus japonicus (Z73939), and Medicago truncatula (BT147767). The symbol * represents the middle value between two sequence numbers.