为了进一步探索木葡聚糖内糖基转移/水解酶(XTH)在柿(Diospyros kaki L.)采后软化中的分子调控机制,应用实时荧光定量PCR技术检测常温下丙烯和1-甲基环丙烯(1-MCP)处理的‘富平尖柿’果实中XTH基因表达量的变化。结果显示,丙烯处理能够促进柿果实成熟软化,增加乙烯释放并使高峰提前到来,而1-MCP处理能够延缓果实软化,抑制乙烯释放。随着柿果实成熟软化推进,4个XTH基因呈现不同的表达方式,且丙烯处理促进了4个XTH基因的表达,而1-MCP处理则抑制它们的表达。其中,DkXTH1和DkXTH2在柿果实成熟软化过程中表达量较高,且二者表达高峰分别在果实成熟的初期和中期,说明DkXTH1和DkXTH2分别与采后柿果实初期和中后期的软化关系密切。结合乙烯释放量结果分析显示,柿果实XTH基因的表达受乙烯调控,对柿果实的成熟软化中具有一定的促进作用。
The regulation of postharvest treatment with propylene and 1-MCP on ethylene release rate and expressions of 1- aminocyclopropane-l-carboxylic acid synthase （ACS） and 1-aminocyclopropane-1-carboxylic acid oxidase （ACO） genes in Fuping Janshi persimmon （Diospyros kaki L.） fruit were investigated. Fruits were treated with propylene and 1-MCP, then stored at 20℃, ethylene release rate of the treated fruits was measured at regular intervals and RNA was extracted for Northern blotting analysis. The results suggested that treatment with propylene accelerated the expressions of ACS and ACO genes and then enhanced the ethylene biosynthesis, while treatment with 1-MCP inhibited the expressions of two genes and their ethylene biosynthesis. Furthermore, different effects on expressions caused by treatments with propylene and 1-MCP existed in various fruit tissues, the inhibitory effect on ACS and ACO genes by 1-MCP was the strongest in pericarp, followed by pulp and core tissues, in the area near fruit stalk, the inhibitory effect was the weakest. While the enhanced effect on ACS and ACO genes by propylene increased from pulp, core, and pericarp to the area near fruit stalk. Expression of each member of ACS and ACO families in various tissues was also completely different, in control and propylene treatment, DKACS3 gene just expressed in the area near fruit stalk and did not express in other tissues, but DKACS2 gene expressed in four tissues by treatment with propylene.
LIU Le, RAO Jing-ping, CHANG Xiao-xiao and YI Shun-chao College of Horticulture, Northwest Agricultural and Forest University/Key Laboratory of Northwest Horticultural Plants Germplasm and Genetic Improvement, Ministry of Agriculture, Yangling 712100, P.R.China
以‘富平尖柿’（Diospyros kaki L．cv．FupingJianshi）为材料，采用RACE方法，首次获得了柿果实多聚半乳糖醛酶（PG）基因的3个全长cDNA（登录号为EU816197、EU816198、EU816199），分别命名为DKPG1、DKPG2、DKPG3。DKPG1全长1616bp，DKPG2全长1654bp，DKPG3全长1545bp。3个基因均含有一个1326bp的开放阅读框，共编码441个氨基酸。通过Blast比对发现该基因核苷酸序列与其他植物已报道的PG基因具有74％～78％的相似性；其氨基酸序列与其他植物的相似性为60％～73％。对GenBank同源性搜索获得的其他植物PG基因氨基酸序列进行系统进化分析，发现其与葡萄、猕猴桃、桃的亲缘关系近，与大豆亲缘关系较远。
为了进一步探索多聚半乳糖醛酸酶(PG)在柿(Diospyros kaki L.)采后软化中的分子调控机制,应用实时荧光定量PCR技术和DNS比色法检测常温下丙烯和1-甲基环丙烯(1-MCP)处理‘富平尖柿'果实中PG基因DkPG1的表达量和PG酶活性的变化。结果显示,随着柿果实成熟软化,DkPG1基因转录水平呈先上升后下降的趋势,其中丙烯处理4d出现表达高峰,比对照提前12d且峰值极显著高于对照,而1-MCP处理的果实中的表达高峰出现在处理后28d,比对照推迟12d峰值极显著低于对照。丙烯处理果实PG酶活性迅速增加,活性峰与DkPG1表达高峰出现在同一天,1-MCP处理的果实PG酶活性明显降低,活性峰出现在DkPG1表达高峰前4d。此外,对不同处理下乙烯释放量和果胶组分变化分析的结果显示DkPG1基因的表达受乙烯调控,进而影响果胶组分代谢。
