摘 要：以“巨峰”葡萄为试材，研究了1-MCP和乙烯处理对采后葡萄果穗品质、叶绿体超微结构及叶绿素降解途径基因表达的影响。结果表明：与对照和乙烯相比，1-MCP降低了葡萄果穗的呼吸强度和褐变，并较好的保持了组织水含量、可溶性糖含量、叶绿素含量。利用实时荧光定量 PCR 技术对叶绿素降解相关基因的表达分析表明，1-MCP处理抑制了叶绿素 b还原酶(NYC1)，7-羟甲基叶绿素还原酶(HCAR)，脱镁叶绿酸a氧化酶(PAO)和stay-green 1(SGR1)基因的表达，而NYC1-like(NOL)、脱镁叶绿素酶(PPH)和红色叶绿素代谢产物还原酶(RCCR)基因不受影响。这表明，1-MCP能够保持葡萄果梗质量，通过抑制与叶绿素分解途径相关的一些基因的表达来延迟果穗褐变，并保持葡萄梗表皮细胞中叶绿体的完整性。
关键词：1-MCP，果梗褐变，叶绿素降解，叶绿体超微结构，葡萄
Effect of 1-MCP on postharvest browning and chlorophyll breakdown pathway genes in grape rachis
Li Jupeng1, FuMaorun1* , Yang Xiaoying1
（1College of Food Science and Technology, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353）
Abstract：The effects of 1-MCP and ethylene on postharvest rachis quality, chloroplast ultrastructure and chlorophyll breakdown pathway genes expression were analysed in the ‘Kyoho’ table grape variety. The results showed that rachises treated with 1-MCP had lower respiratory intensity and browning index, and higher tissue water content, soluble sugar content, lightness, greenness and chlorophyll content than did the control, in contrast to the samples treated with ethylene. Additionally, the expression of all known genes involved in the chlorophyll breakdown pathway was examined by real-time qPCR. The transcript abundance of non-yellow colouring 1 (NYC1), 7-hydroxymethyl chl a reductase (HCAR), pheophorbide a oxygenase (PAO), and stay-green 1 (SGR1) genes was inhibited by 1-MCP treatment, whereas that of NYC1-like (NOL), pheophytin pheophorbide hydrolase (PPH), and red chlorophyll catabolite reductase (RCCR) genes was not affected. All these findings indicated that 1-MCP could maintain rachis quality, delay rachis browning by suppressing the expression of some genes associated with the chlorophyll breakdown pathway, and maintain the integrity of chloroplasts in the grape rachis.
Keywords: 1-MCP; rachis browning; chlorophyll breakdown; chloroplast ultrastructure; grape
葡萄果梗的品质对消费者偏好和市场价格有显著的影响。果梗褐变降低了采后葡萄的品质，这是影响鲜食葡萄品质的非常重要的问题[1]。以前研究表明褐变的主要原因与失水有关[2]。最近的研究表明，水分损失尽管非常重要，但并不是褐变的唯一因素[3]。Balic等[4]发现，当收获前1 d施用细胞分裂素(CKs)时，在冷藏期(0 oC)90天后，果穗的褐变受到明显抑制。Li等[5]研究表明，1-MCP可延迟葡萄梗的褐变。气调包装(MAP)通过延迟叶绿素降解和褐色化合物积累来保持果梗品质[6]。这些研究表明果梗褐变是复杂的生理过程。
1-MCP是一种乙烯效应抑制剂，广泛用于水果保鲜。研究表明，1-MCP能降低鳄梨[7]和梅果[8]叶绿素的降解。1-MCP可以延缓衰老过程，如延缓了非跃变型果实的果梗褐变[9]。吴小华等[10]研究发现，1-MCP处理能显著抑制黄冠梨常温贮藏期间果心褐变的发生。然而，1-MCP和乙烯对果梗褐变过程中叶绿素降解的分子调控机制尚未有研究。
作者：李具鹏 傅茂润 杨晓颖