Key Laboratory of Protected Horticulture of Education Ministry and Liaoning Province, College of Horticulture, Shenyang Agricultural University, National and Local Joint Engineering Research Centre of Northern Horticultural, Facilities Design and Application Technology (Liaoning), Shenyang 110866, China.
Int J Mol Sci. 2022 Aug 29;23(17):9805. doi: 10.3390/ijms23179805.
Ripened oriental melon () with orange-colored flesh is rich in β-carotene. Lycopene β-cyclase (LCYB) is the synthetic enzyme that directly controls the massive accumulation of β-carotene. However, the regulatory mechanism underlying the -mediated β-carotene accumulation in oriental melon is fairly unknown. Here, we screened and identified a transcription factor, CmNAC34, by combining bioinformatics analysis and yeast one-hybrid screen with promoter. CmNAC34 was located in the nucleus and acted as a transcriptional activator. The expression profile of was consistent with that of during the fruit ripening. Additionally, the transient overexpression of CmNAC34 in oriental melon fruit promoted the expression of and enhanced β-carotene concentration, while transient silence of CmNAC34 in fruit was an opposite trend, which indicated CmNAC34 could modulate -mediated β-carotene biosynthesis in oriental melon. Finally, the yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), β-glucuronidase (GUS) analysis assay, and luciferase reporter (LUC) assay indicated that CmNAC34 could bind to the promoter of and positively regulated the transcription level. These findings suggested that CmNAC34 acted as an activator to regulate β-carotene accumulation by directly binding the promoter of , which provides new insight into the regulatory mechanism of carotenoid metabolism during the development and ripening of oriental melon.
成熟的东方甜瓜（）果肉呈橙黄色，富含β-胡萝卜素。番茄红素β-环化酶（LCYB）是直接控制β-胡萝卜素大量积累的合成酶。然而，东方甜瓜中 -介导的β-胡萝卜素积累的调控机制尚不清楚。在这里，我们通过生物信息学分析和酵母单杂交筛选与 启动子相结合，筛选并鉴定了一个转录因子 CmNAC34。CmNAC34 位于细胞核内，作为转录激活因子。的表达谱与果实成熟过程中 的表达谱一致。此外，CmNAC34 在东方甜瓜果实中的瞬时过表达促进了 的表达并增强了β-胡萝卜素浓度，而在果实中瞬时沉默 CmNAC34 则呈现相反的趋势，这表明 CmNAC34 可以调节 -介导的东方甜瓜中β-胡萝卜素的生物合成。最后，酵母单杂交（Y1H）、电泳迁移率变动分析（EMSA）、β-葡萄糖醛酸酶（GUS）分析测定和荧光素酶报告基因（LUC）分析表明，CmNAC34 可以与 启动子结合并正向调节 转录水平。这些发现表明 CmNAC34 通过直接结合 启动子作为激活子来调节β-胡萝卜素的积累，这为东方甜瓜发育和成熟过程中类胡萝卜素代谢的调控机制提供了新的见解。
