Liu Yanfei, Lv Guowen, Chai Jiaxin, Yang Yaqi, Ma Fengwang, Liu Zhande
College of Horticulture, Northwest A&F University, Xianyang 712100, China.
College of Life Science, Northwest A&F University, Xianyang 712100, China.
Foods. 2021 Dec 5;10(12):3017. doi: 10.3390/foods10123017.
The development of yellow color is an important aspect of fruit quality in yellow fleshed kiwifruit during fruit ripening, and it has a large influence on consumer preference. The yellow color is determined by carotenoid accumulation and chlorophyll degradation and is likely affected by ethylene production. This study investigates the expression of carotenoid, chlorophyll degradation, and ethylene response factors in 'Qihong' fruit, which had reached the near ripening stage (firmness ≈ 20 N) and were either left untreated (controls) or treated with 0.5 μL L of 1-MCP for 12 h. Both the accumulation of -carotene (not lutein) and degradation of chlorophyll and increased in response to the 1-MCP treatment, resulting in more yellow colored flesh in the 1-MCP treated fruit with higher carotenoid and lower chlorophyll contents. 1-MCP up-regulated , , and , but reduced the expression of . These four genes were correlated with the concentrations of -carotene and the chlorophylls. The expression of three ethylene response factors, including , , and were delayed and down-regulated in 1-MCP treated fruit, showing the highest correlation with the expression of , , , and . Dual-Luciferase assays showed that 1-MCP treatment not only eliminated the inhibition of on the promoters of both and , but also reduced the activation of and on the promoter. Our findings indicate that , , and may play an important role in the response to 1-MCP treatment during the fruit eating ripe stage, which likely altered the promoter activities of carotenoid and chlorophyll-related genes (, and ) to regulate their transcripts, resulting in more yellow color in the fruit flesh of 'Qihong'.
在黄肉猕猴桃果实成熟过程中，果实变黄是果实品质的一个重要方面，对消费者偏好有很大影响。黄色由类胡萝卜素积累和叶绿素降解决定，可能受乙烯产生的影响。本研究调查了‘齐红’果实中类胡萝卜素、叶绿素降解和乙烯反应因子的表达情况，这些果实已达到近成熟阶段（硬度约为20 N），要么未处理（对照），要么用0.5 μL/L的1-甲基环丙烯（1-MCP）处理12小时。1-MCP处理后，β-胡萝卜素（而非叶黄素）的积累以及叶绿素a和叶绿素b的降解均增加，导致1-MCP处理的果实果肉颜色更黄，类胡萝卜素含量更高，叶绿素含量更低。1-MCP上调了PSY1、PDS和ZDS，但降低了LYCE的表达。这四个基因与β-胡萝卜素和叶绿素的浓度相关。包括ERF1、ERF2和ERF3在内的三个乙烯反应因子的表达在1-MCP处理的果实中延迟且下调，与PSY1、PDS、ZDS和LYCE的表达相关性最高。双荧光素酶分析表明，1-MCP处理不仅消除了ERF1对PSY1和PDS启动子的抑制作用，还降低了ERF2和ERF3对LYCE启动子的激活作用。我们的研究结果表明，ERF1、ERF2和ERF3可能在果实食用成熟阶段对1-MCP处理的反应中起重要作用，这可能改变了类胡萝卜素和叶绿素相关基因（PSY1、PDS和LYCE）的启动子活性，以调节它们的转录本，从而使‘齐红’果实的果肉颜色更黄。
