Physiological and Transcriptomic Analyses of IAA-Induced Inhibition of Chlorophyll Formation in Potato Tubers Post-Harvest

Light exposure can induce post-harvest potato tubers to become green due to the accumulation of chlorophyll (Chl) and the formation of glycoside alkaloids, posing a potential risk to food safety. This study evaluated exogenous indole-3-acetic acid (IAA) to inhibit greening in <i>Solanum tuberosum</i> cv. Tongshu 31. IAA treatment maintained a relatively high <i>a</i>* value and significantly reduced both Chl content and the accumulation of toxic steroidal glycoalkaloids (SGAs), such as α-solanine and α-chaconine. In addition, IAA treatment also delayed the decrease in hardness and weight loss of tubers during storage, and helped maintain a high content of starch and reduce sugar. Transcriptome analysis revealed that IAA downregulated <i>HEMA1</i>, <i>CHLH</i>, and <i>GUN4</i>, among other key genes in the Chll biosynthesis pathway, thereby inhibiting Chl accumulation. IAA also modulated hormone networks, increasing gibberellin (GA) and jasmonic acid (JA), decreasing abscisic acid (ABA), and activating signaling genes (<i>StGID1</i>, <i>StJAR1</i>, <i>StPYR1</i>, <i>StPYL4</i>), enhancing tuber defense. These results indicate that IAA can inhibit the synthesis of Chl by regulating gene expression. This study provides a new strategy for alleviating the greening problem of potatoes and explains the potential mechanism by which IAA inhibits Chl synthesis in potato tubers.