Genome-wide identification and characterization of greenbug-inducible NAC transcription factors in sorghum

Authors: HENYOU, ZHANG - Oklahoma State University; Huang, Yinghua

Submitted to: Molecular Biology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2023
Publication Date: 1/25/2024
Citation: Henyou, Z., Huang, Y. 2024. Genome-wide identification and characterization of greenbug-inducible NAC transcription factors in sorghum. Molecular Biology Reports. https://doi.org/10.1007/s11033-023-09158-x.
DOI: https://doi.org/10.1007/s11033-023-09158-x

Interpretive Summary: Sorghum is an important cereal crop that is commonly used as feed for livestock in the U.S. but also one of the most important staple foods for millions of people in Africa and Asia. Greenbug, one of the cereal aphids, is a major insect pest of sorghum causing significant economic damage. A USDA-ARS sorghum research laboratory in Stillwater, Oklahoma has been investigating host plant resistance to greenbug for helping sorghum growers to protect their sorghum crops. Here they report the recent research results on identification and characterization of the sorghum NAC (SbNAC) gene family through the genome-wide analysis. As a result, a total of 112 SbNAC genes were identified in the sorghum genome and they unevenly distribute in clusters at the telmoeric ends of each chromosome. Structure analysis revealed the diverse structures of the genes with highly variable number of exons among those SbNAC genes. Additional analysis showed a majority of SbNAC genes with specific temporal and spatial expression patterns according to the results of RNA-sequencing analysis, suggesting their diverse functions in sorghum growth and development. Another exciting result is that nine SbNAC genes exhibited differential expression between the resistant and susceptible cultivars in response to greenbug infestation, suggesting they may play a role in plant defense against the aphid. These results offer a new insight into the functions of these SbNAC genes in plant defense against the aphid pest and when confirmed, the SbNAC genes may contribute a tool in the integrated pest management for sorghum crops.

Technical Abstract: Sorghum is an important cereal crop grown worldwide because of its multipurpose uses such as food, forage, and bioenergy feedstock and its wide range of adaption even in marginal environments. Greenbug can cause severe damage to sorghum plants and yield loss by sucking nutrients from the host while introducing phytotoxins into the plants. Plant NAC transcription factors (TFs) have been reported to have diverse functions in plant development and plant defense. In this study, a comprehensive analysis of the NAC (SbNAC) gene family in sorghum was conducted through genome-wide analysis. A total of 112 full-length NAC genes have been identified in the sorghum genome. These SbNAC genes are phylogenetically clustered into 15 distinct subfamilies and unevenly distribute in clusters at the telmoeric ends of each chromosome. Twelve pairs of SbNAC genes are possibly involved in the segmental duplication among nine chromosomes except chromosome 10. Structure analysis showed the diverse structures with highly variable number of exons in the SbNAC genes. Furthermore, a majority of the SbNAC genes showed the specific temporal and spatial expression patterns according to the results of RNA-seq analysis, suggesting their diverse functions during sorghum growth and development. We have also identified nine greenbug-inducible SbNAC genes by comparing the expression profiles between two sorghum genotypes (susceptible BTx623 and resistant PI607900) in response to infestation by greenbug. Our systematic analysis of the NAC gene expression profiles provides both a preliminary survey into their roles in plant defense against insect pests and a useful reference for in-depth characterization of the SbNAC genes and the regulatory network that contribute genetic resistance to greenbug.