Justice Norvienyeku, Lili Lin, Abdul Waheed, Xiaomin Chen, Jiandong Bao, Sami Rukaiya Aliyu, Lianyu Lin, Ammarah Shabbir, Wajjiha Batool, Zhenhui Zhong, Jie Zhou, Guodong Lu, Zonghua Wang

Plant Biotechnology Journal; 2021 Mar; 19(3):589-601.  doi: 10.1111/pbi.13488. 

Abstract

Rice cultivars from japonica and indica lineage possess differential resistance against blast fungus as a result of genetic divergence. Whether different rice cultivars also show distinct metabolomic changes in response to P. oryzae, and their role in host resistance, are poorly understood. Here, we examine the responses of six different rice cultivars from japonica and indica lineage challenged with P. oryzae. Both susceptible and resistant rice cultivars expressed several metabolites exclusively during P. oryzae infection, including the saponin Bayogenin 3-O-cellobioside. Bayogenin 3-O-cellobioside level in infected rice directly correlated with their resistant attributes. These findings reveal, for the first time to our knowledge that besides oat, other grass plants including rice produces protective saponins. Our study provides insight into the role of pathogen-mediated metabolomics reprogramming in host immunity. The correlation between Bayogenin 3-O-Cellobioside levels and blast resistance suggests that engineering saponin expression in cereal crops represents attractive and sustainable disease management.

See: https://pubmed.ncbi.nlm.nih.gov/33043566/

Figure 4: Clustering and expression profile of putative saponin biosynthesis gene in rice during P. oryzae infection. (a). the Neighbour‐joining tree showed the clustering 145 rice diphosphate glucuronyltransferases (UDP/GTs) into 33 different subfamilies (groups) based on conserved alignable motifs. Each group is defined by a colour shade and consists of 1‐15 genes. (b). Displayed the chromosomal distribution and locations of UDP/GTs gene clusters in rice. The blue each vertical bar with upper and lower or (long and short) arms represents rice chromosome. The position of the blue circle (connecting the upper and lower arms) on each chromosome indicate represents the centromeric region. The numbering (Chr1‐Chr12) on top of each vertical blue bar corresponds to chromosome number. Set of genes aligned to red solid lines projecting from the chromosome represents a single cluster; therefore, the number of red solid lines on each chromosome reflects the number of UDP/GTs gene clusters identified on the respective chromosome. (c). Showed the comparative expression pattern of 108 differentially expressed UDP/GTs susceptible (CO39 and NPB) and resistant (Pi‐gm) rice cultivars challenged with the rice blast fungus. (d). The heatmap represent folds expression pattern of rice‐specific β‐amyrin synthase genes in blast resistant and susceptible rice cultivars challenged with P. oryzae. Note the expression these 106 were exclusively in response to infection and were not detected in the non‐inoculated control groups. Each coloured dot in or outside box plot represents the unique expression level (log₂ FPKM) of UDP/GTs gene in the treated rice cultivars with a P ≤ 0.05. The asterisks at the whiskers indicate the lower and upper outliers.