Abstract
BACKGROUND: Autophagy represents an ancient cytoprotective program that sustains cell viability under metabolic or environmental stresses via targeted recycling of cellular components. However, the contribution of ATG18s in maize is ambiguous. RESULTS: This work aims to identify and characterize the maize ZmATG18 subfamily genes at the whole-genome level and a total of eight ZmATG18 subfamily genes were identified. Gene duplication analysis showed that segmental duplication events were involved in the ZmATG18 gene evolution process. Promoter analysis suggested that ZmATG18 genes contained numerous stress and hormone-related elements. The phylogenetic relationships, conserved motifs and gene structure analysis revealed that ZmATG18 subfamily members were highly comparable to their counterparts in Arabidopsis, rice and tomato. The expression profiles of ZmATG18 gene family during development revealed that ZmATG18 genes exhibited distinct tissue-specific expression patterns at different developmental stages in maize. Furthermore, the role of ZmATG18a was analyzed under drought stress. Subcellular localization showed that ZmATG18a was present in both the cytoplasm and nucleus. ZmATG18a plays a positive role in drought stress since the stop-of-gain EMS mutant of ZmATG18a was more sensitive to drought stress whereas the Mutator mutant which showed higher ATG18a expression was less sensitive to drought stress. CONCLUSIONS: In this study, we identified the ZmATG18 subfamily members in B73 inbred line for their physicochemical properties, gene structures, conserved motifs, phylogenetic analysis, expression profile analysis. Finally, ZmATG18a was demonstrated to play a positive role in drought stress. This study provides insights into the diversity of ZmATG18 subfamily genes and their potential role in drought stress. More importantly, ZmATG18a was identified to be potential target for genetic engineering to improve drought stress tolerance of maize.