Postharvest ethylene treatment suppressed potato tuber sprouting through modulation of phytohormone regulation (P-25)

Ethylene is registered for commercial use as a postharvest potato tuber sprout suppressor in several countries. However, there is a significant knowledge gap regarding mode of action of ethylene and its overall impact on dormancy regulation of tubers at molecular level. The objective of this study is to integrate transcriptomic and targeted metabolomic analyses to elucidate critical hormonal regulation of potato tuber impacted by ethylene treatment. Certified mini tubers of cv. Russet Burbank were exposed to continuous ethylene treatment (10 ppm) for 15-weeks and then kept for additional 3-weeks under air application. Emergence and growth of sprout was monitored, and primary bud and tuber flesh tissues were collected at 3-weeks interval for transcriptome and hormone analysis. Ethylene treatment resulted in delayed and lower sprout growth score when compared with the control (air-flow treatment) until the tubers kept under ethylene and air (15 + 3-weeks) treatments. Ethylene treatment resulted in increased transcript abundance of genes associated with ethylene biosynthesis (ACS6, ACO4) and signaling (ERF1A). On the contrary, auxin signaling (IAA14, PIN3, ARF19) and gibberellic acid (GA) biosynthesis and signaling (GA20OX1, GA3OX1) genes had decreased transcript abundance, aligning with reduced levels of indole-3-acetic acid (IAA) and gibberellin A6 (GA6) content in primary bud under ethylene treatment. Abscisic acid (ABA) catabolism genes (CYP707A1, CYP707A4) also had decreased abundance with ethylene treatment leading to elevated ABA levels. Jasmonic acid (JA) derivatives increased in tuber bud tissues, correlating with increased transcript abundance of biosynthesis (AOC2, OPR1) and signaling genes (MYC2, TIFY10A), suggesting stress response associated modulatory role of JA under ethylene treatment. Collectively, these findings demonstrate ethylene’s role as a key regulator of tuber dormancy, through suppression of IAA, cytokinin, and activation of ethylene, ABA, and JA signaling. The study provides insights into hormonal crosstalk, explaining molecular basis for ethylene-based postharvest management strategies.