Chen Hao, Cao Songxiao, Jin Yazhong, Tang Yufan, Qi Hongyan
Key Laboratory of Protected Horticulture of Ministry of Education and Liaoning Province, College of Horticulture, Shenyang Agricultural University Shenyang, China.
Key Laboratory of Protected Horticulture of Ministry of Education and Liaoning Province, College of Horticulture, Shenyang Agricultural UniversityShenyang, China; Department of Horticulture, College of Agriculture, Heilongjiang Bayi Agricultural UniversityDaqing, China.
Front Physiol. 2016 Jun 28;7:254. doi: 10.3389/fphys.2016.00254. eCollection 2016.
Alcohol dehydrogenase (ADH) plays an important role in aroma volatile compounds synthesis of plants. In this paper, we tried to explore the relationship between CmADHs and the volatile organic compounds (VOCs) in oriental melon. Three different aroma types of melon were used as materials. The principle component analysis of three types of melon fruit was conducted. We also measured the CmADHs expression level and enzymatic activities of ADH and alcohol acyl-transferase (AAT) on different stages of fruit ripening. An incubation experiment was carried out to investigate the effect of substrates and inhibitor (4-MP, 4-methylpyrazole) on CmADHs expression, ADH activity, and the main compounds of oriental melon. The results illustrated that ethyl acetate, hexyl acetate (E,Z)-3,6-nonadien-1-ol and 2-ethyl-2hexen-1-ol were the four principal volatile compounds of these three types of melon. AAT activity was increasing with fruit ripening, and the AAT activity in CH were the highest, whereas ADH activity peaked on 32 DAP, 2 days before maturation, and the ADH activity in CB and CG were higher than that in CH. The expression pattern of 11 CmADH genes from 24 to 36 day after pollination (DAP) was found to vary in three melon varieties. CmADH4 was only expressed in CG and the expression levels of CmADH3 and CmADH12 in CH and CB were much higher than that in CG, and they both peaked 2 days before fruit ripening. Ethanol and 4-MP decreased the reductase activity of ADH, the expression of most CmADHs and ethyl acetate or hexyl acetate contents of CB, except for 0.1 mM 4-MP, while aldehyde improved the two acetate ester contents. In addition, we found a positive correlation between the expression of CmADH3 and CmADH12 and the key volatile compound of CB. The relationship between CmADHs and VOCs synthesis of oriental melon was discussed.
乙醇脱氢酶（ADH）在植物香气挥发性化合物合成中发挥着重要作用。本文旨在探究甜瓜中CmADHs与挥发性有机化合物（VOCs）之间的关系。以三种不同香气类型的甜瓜为材料，对三种甜瓜果实进行了主成分分析。同时测定了果实成熟不同阶段的CmADHs表达水平以及ADH和乙醇酰基转移酶（AAT）的酶活性。开展了一项温育实验，以研究底物和抑制剂（4-MP，4-甲基吡唑）对CmADHs表达、ADH活性以及甜瓜主要化合物的影响。结果表明，乙酸乙酯、乙酸己酯、（E，Z）-3,6-壬二烯-1-醇和2-乙基-2-己烯-1-醇是这三种甜瓜的四种主要挥发性化合物。AAT活性随果实成熟而增加，且CH中的AAT活性最高，而ADH活性在授粉后32天（DAP）达到峰值，即成熟前2天，且CB和CG中的ADH活性高于CH。发现授粉后24至36天（DAP），11个CmADH基因在三个甜瓜品种中的表达模式存在差异。CmADH4仅在CG中表达，CH和CB中CmADH3和CmADH12的表达水平远高于CG，且二者均在果实成熟前2天达到峰值。乙醇和4-MP降低了ADH的还原酶活性、大多数CmADHs的表达以及CB中乙酸乙酯或乙酸己酯的含量，但0.1 mM 4-MP除外，而醛提高了两种乙酸酯的含量。此外，我们发现CmADH3和CmADH12的表达与CB的关键挥发性化合物之间存在正相关。本文还讨论了CmADHs与甜瓜VOCs合成之间的关系。
