An R2R3-MYB transcription factor TgMYB44 positively regulates petal senescence by enhancing ABA biosynthesis in tulip

Transcriptome identification and functional characterization of an ABA-induced R2R3-MYB transcription factor involved in flower petal senescence and abiotic stress responses in Tulipa gesneriana. Tulips (Tulipa gesneriana L.) are cultivated worldwide and hold significant importance in the international markets of ornamental flowers. As a cut flower, petal senescence determines the flower longevity, which seriously affects the ornamental and economic value of tulips. Therefore, revealing the regulation mechanism of petal senescence is of great significance for flower lifespan improvement and cut flowers preservation. Here, we identified 40 MYB genes from transcriptome analysis during the process of flower opening and senescence in tulip. Among them, an ABA-induced R2R3-MYB TgMYB44 is found to be significantly downregulated in senescent petals. Overexpression of TgMYB44 altered the sensitivity to ABA, salt, and osmotic stress, as well as enhanced ABA accumulation and ABA-induced leaf senescence in Arabidopsis. Besides, silencing TgMYB44 in tulip delayed petal senescence by modulating ABA biosynthesis. Taken together, this study proposed that TgMYB44 functions as a positive regulator for petal senescence by enhancing ABA biosynthesis in tulips. These findings advance our understanding of the ABA-induced petal senescence in tulip, and also provide new strategies for biotechnological manipulation of flower longevity and postharvest preservation for tulip cut flowers.