Comprehensive Analysis of Autophagy-Related Genes in Sweet Orange () Highlights Their Roles in Response to Abiotic Stresses.

Autophagy is a highly conserved intracellular degradation pathway that breaks down damaged macromolecules and/or organelles. It is involved in plant development and senescence, as well as in biotic and abiotic stresses. However, the autophagy process and related genes are largely unknown in citrus. In this study, we identified 35 autophagy-related genes (autophagy-related genes () of , Cs) in a genome-wide manner from sweet orange (). Bioinformatic analysis showed that these CsATGs were highly similar to ATGs in both sequence and phylogeny. All the were randomly distributed on nine known (28 genes) and one unknown (7 genes) chromosomes. Ten were predicted to be segmental duplications. Expression patterns suggested that most of the were significantly up- or down-regulated in response to drought; cold; heat; salt; mannitol; and excess manganese, copper, and cadmium stresses. In addition, two members, and , were cloned from sweet orange and ectopically expressed in . The and transgenic plants showed enhanced tolerance to osmotic stress, salt, as well as drought () or cold (), compared to wild-type plants. These results highlight the essential roles of genes in abiotic stresses.