Genome-wide identification and expression analysis of the NAC transcription factor family in <i>Saccharum spontaneum</i> under different stresses

Abstract

The <i>NAC</i> (<i>NAM, ATAF1/2</i>, and <i>CUC2</i>) transcription factor family is one of the largest families unique to plants and is involved in plant growth and development, organs, morphogenesis, and stress responses. The <i>NAC</i> family has been identified in many plants. As the main source of resistance genes for sugarcane breeding, the <i>NAC</i> gene family in the wild species <i>Saccharum spontaneum</i> has not been systematically studied. In this study, 115 <i>SsNAC</i> genes were identified in the <i>S. spontaneum</i> genome, and these genes were heterogeneously distributed on 25 chromosomes. Phylogenetic analysis divided the <i>SsNAC</i> family members into 18 subgroups, and the gene structure and conserved motif analysis further supported the phylogenetic classification. Four groups of tandemly duplicated genes and nine pairs of segmentally duplicated genes were detected. The <i>SsNAC</i> gene has different expression patterns at different developmental stages of stems and leaves. Further qRT-PCR analysis showed that drought, low-temperature, salinity, pathogenic fungi, and other stresses as well as abscisic acid (ABA) and methyl jasmonate (MeJA) treatments significantly induced the expression of 12 <i>SsNAC</i> genes, indicating that these genes may play a key role in the resistance of <i>S. spontaneum</i> to biotic and abiotic stresses. In summary, the results from this study provide comprehensive information on the <i>NAC</i> transcription factor family, providing a reference for further functional studies of the <i>SsNAC</i> gene.