Evolution and characterization of the AhRAF4 NB-ARC gene family induced by Aspergillus flavus inoculation and abiotic stresses in peanut

Authors: DENG, YE - Fujian Agricultural & Forestry University; CHEN, HUA - Fujian Agricultural & Forestry University; ZHANG, CHONG - Fujian Agricultural & Forestry University; CAI, TIECHENG - Fujian Agricultural & Forestry University; ZHANG, B - Fujian Agricultural & Forestry University; ZHOU, S - Fujian Agricultural & Forestry University; FOUNTAIN, JAKE - University Of Georgia; PAN, RONG-LONG - Tsinghua University; Guo, Baozhu; ZHUANG, WEI-JIAN - Fujian Agricultural & Forestry University

Submitted to: Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2018
Publication Date: 6/7/2018
Citation: Deng, Y., Chen, H., Zhang, C., Cai, T., Zhang, B., Zhou, S., Fountain, J., Pan, R., Guo, B., Zhuang, W. 2018. Evolution and characterization of the AhRAF4 NB-ARC gene family induced by Aspergillus flavus inoculation and abiotic stresses in peanut. Plant Biology. 20(4):641-802. https://doi.org/10.1111/plb.12726.
DOI: https://doi.org/10.1111/plb.12726

Interpretive Summary: Cultivated peanuts are grown in over 100 countries and provide the fourth world’s largest edible oil and the second largest vegetative proteins for human and animal consumption. Aflatoxin contamination in peanut is also a serious food safety issue to human health around the world. This toxin is produced by fungi that cause the disease on peanut as it is growing. Finding disease resistance genes to fight against these fungi is a key strategy for genetic improvement of peanut in order to mitigate aflatoxin contamination. In this study, a specific gene was identified by using gene expression microarray technology. This gene was inducible by A. flavus infection and in association with stresses on the plants such as drought and high temperatures that make peanut more susceptible. The cloning of the gene under these conditions indicates that this gene may play an important role in disease resistance against fungal pathogens. Future research will be conducted to investigate the resistance genes (R-genes) effectiveness in the breeding program as marker assisted selection for resistance to A. flavus infection and aflatoxin contamination. R-Genes are genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins.

Technical Abstract: Aflatoxin contamination in peanut is a serious food safety issue to human health around the world. Finding disease resistance genes is a key strategy for genetic improvement in breeding to deal with this issue. We have identified an Aspergillus flavus-induced NBS-LRR gene, AhRAF4, using a microarray-based approach. By comparison of 23 sequences from three species using phytogenetics, protein secondary structure, and three-dimensional structural analyses, AhRAF4 was revealed to be derived from Arachis duranensis by recombination, and has newly evolved into a family of several members characterized by duplications and point mutations. However, the members of the family descended from A. ipaensis was lost following tetraploidization. The AhRAF4 was slightly up-regulated by low temperature, drought, salicylic acid, and ethylene, but down-regulated by methyl jasmonate. The distinct responses upon A. flavus inoculation and the differential reactions between resistant and susceptible varieties indicated that AhRAF4 may play a role in defense responses. Temporal and spatial expression and the phenotype of transformed protoplasts suggested that AhRAF4 may be associated with pericarp development. Because tetraploid cultivated peanuts are vulnerable to many pathogens, an exploration of R-genes may provide an effective method for genetic improvement of peanut cultivars.