Genome-Wide and Transcriptome Analysis of Autophagy-Related ATG Gene Family and Their Response to Low-Nitrogen Stress in Sugar Beet

Sugar beet (<i>Beta vulgaris</i> L.) is a significant global crop for sugar production, with nitrogen playing a crucial role in its growth, development, and sugar yield. Autophagy facilitates nutrient reabsorption and recycling under nutrient stress by degrading intracellular components, thereby enhancing plant nitrogen use efficiency. However, research on the autophagy response to low-nitrogen stress in sugar beet remains limited. In this study, 29 members of the <i>ATG</i> gene family were identified, with genes within the same subfamily displaying similar gene structures and conserved domains. These <i>ATG</i> genes in sugar beet contain various hormone and stress-response elements. Transcriptome data and qRT-PCR analysis further revealed that the expression levels of <i>ATG4</i>, <i>ATG8b</i>, <i>ATG18a, TOR</i>, <i>NBR1</i>, <i>ATI, ATG8a</i>, <i>ATG12</i>, and <i>VTI12a</i> were significantly upregulated under low-nitrogen stress, with most genes showing high expression levels across different tissues. These <i>ATG</i> genes are thus likely involved in regulating autophagy in response to low-nitrogen conditions. The observed increase in autophagosome numbers further supports the induction of autophagy by low-nitrogen stress. These nine genes can be considered key candidates for further research on nitrogen-sensitive autophagy in the sugar beet <i>ATG</i> gene family. This study provides a comprehensive analysis of the structure and biological functions of <i>ATG</i> genes in sugar beet, offering genetic resources for future efforts to improve sugar beet varieties through genetic engineering. Such efforts could focus on regulating autophagy to enhance nitrogen use efficiency and develop new germplasm.