Key Laboratory of Horticultural Plant Germplasm Resources Utilization in Northwest China, College of Horticulture, Northwest A&F University, Yangling 712100, China.
Int J Mol Sci. 2013 Nov 7;14(11):22082-101. doi: 10.3390/ijms141122082.
A full-length cDNA coding for hydroperoxide lyase (CsHPL) was isolated from cucumber fruits of No. 26 (Southern China type) and No.14-1 (Northern China type), which differed significantly in fruit flavor. The deduced amino acid sequences of CsHPL from both lines show the same and significant similarity to known plant HPLs and contain typical conserved domains of HPLs. The recombinant CsHPL was confirmed to have 9/13-HPL enzymatic activity. Gene expression levels of CsHPL were measured in different organs, especially in fruits of different development stages of both lines. The HPL activities of fruit were identified basing on the catalytic action of crude enzyme extracts incubating with 13-HPOD (13-hydroperoxy-(9Z,12E)-octadecadienoic acid) and 13-HPOD + 9-HPOD (9-hydroperoxy-(10E,12Z)-octadecadienoic acid), and volatile reaction products were analyzed by GC-MS (gas chromatography-mass spectrometry). CsHPL gene expression in No. 26 fruit occurred earlier than that of total HPL enzyme activity and 13-HPL enzyme activity, and that in No. 14-1 fruit was consistent with total HPL enzyme activity and 9-HPL enzyme activity. 13-HPL enzyme activities decreased significantly and the 9-HPL enzyme activities increased significantly with fruit ripening in both lines, which accounted for the higher content of C6 aldehydes at 0-6 day post-anthesis (dpa) and higher content of C9 aldehydes at 9-12 dpa.
从 26 号（中国南方型）和 14-1 号（中国北方型）黄瓜果实中分离出全长 cDNA 编码的氢过氧化物裂解酶（CsHPL），这两个品系在果实风味上有显著差异。来自两条线的 CsHPL 的推导氨基酸序列与已知的植物 HPL 具有相同的显著相似性，并包含 HPL 的典型保守结构域。重组 CsHPL 被确认为具有 9/13-HPL 酶活性。在不同器官，特别是两条线不同发育阶段的果实中，测量了 CsHPL 的基因表达水平。根据粗酶提取物与 13-HPOD（13-羟基-（9Z，12E）-十八碳二烯酸）和 13-HPOD + 9-HPOD（9-羟基-（10E，12Z）-十八碳二烯酸）孵育时的催化作用，确定了果实中 HPL 活性，并通过 GC-MS（气相色谱-质谱）分析了挥发性反应产物。26 号果实中 CsHPL 基因的表达早于总 HPL 酶活性和 13-HPL 酶活性，而 14-1 号果实中的 CsHPL 基因表达与总 HPL 酶活性和 9-HPL 酶活性一致。两条线的果实成熟过程中，13-HPL 酶活性显著下降，9-HPL 酶活性显著增加，这导致在授粉后 0-6 天（dpa）醛 C6 含量较高，在 9-12 dpa 醛 C9 含量较高。
