As an important horticultural plant, the orchid is widely distributed in its natural habitat and faces various environmental stresses, among which nutrient recycling and stress resistance are of great concern. During these processes, autophagy is an essential pathway, which is a conserved self-eating process that degrades macromolecular components and recycles cell materials or nutrients during developmental processes or under stress conditions. Two ubiquitin-like systems (UBLs) play a major role in the initiation of autophagy and are associated with two key proteins: ATG8 and ATG12. In this study, we identified and refined the UBL-related genes in orchids and performed phylogenetic reconstruction together with other plant species. We found that the orchid had unique domains in UBL-related genes, indicating potential functional diversification in the ATG8 system in plants. Transcriptome and protein tertiary structure prediction indicated that conserved domains that are vital for the canonical function of ATG12 are incomplete in orchids, in which a novel mechanism of autophagy may have evolved.

作为重要的园艺植物，兰花在其自然栖息地中分布广泛，并面临各种环境压力，其中营养物质的循环利用和抗逆性受到极大关注。在这些过程中，自噬是必不可少的途径，这是一种保守的自我饮食过程，在发育过程中或在压力条件下，该过程会降解大分子成分并回收细胞物质或营养。两个类似泛素的系统（UBL）在自噬的启动中起主要作用，并且与两个关键蛋白：ATG8和ATG12相关。在这项研究中，我们鉴定并完善了兰花中与UBL相关的基因，并与其他植物物种一起进行了系统发育重建。我们发现兰花在UBL相关基因中具有独特的结构域，表明植物的ATG8系统具有潜在的功能多样化。转录组和蛋白质三级结构预测表明，对于ATG12的正常功能至关重要的保守域在兰花中是不完整的，其中可能已经进化出一种新的自噬机制。