棗木葡聚糖轉(zhuǎn)移酶基因的表達(dá)分析

摘 要：為研究木葡聚糖內(nèi)糖基轉(zhuǎn)移酶（XTH）與棗果實(shí)生長及成熟軟化的關(guān)系，采用普通PCR及3’ RACE擴(kuò)增技術(shù)，從鮮棗品種梨棗和沾化冬棗中均克隆到XTH基因的部分序列；同時(shí)，利用實(shí)時(shí)熒光定量PCR技術(shù)，研究了2個(gè)鮮棗品種的不同生長期其采后常溫貯藏過程中XTH基因的相對表達(dá)量的變化。結(jié)果表明，從梨棗和沾化冬棗中克隆的XTH基因片段均為776 bp，包含636 bp的開放閱讀框，編碼212個(gè)氨基酸，分別命名為ZjXTH1和ZjXTH2（登錄號分別為：HQ896312和HQ896313）。通過Blastn和Blastp對序列同源性進(jìn)行比對分析，ZjXTH基因與已登錄的其他物種的XTH基因相似性在68%～78%。實(shí)時(shí)定量PCR表達(dá)分析表明，ZjXTH基因的表達(dá)從盛花后51 d開始積累，并且在棗果實(shí)成熟軟化過程中的表達(dá)量顯著高于果實(shí)的生長期。梨棗ZjXTH1基因在采后貯藏中呈現(xiàn)“上升-下降-上升”的變化規(guī)律，在果實(shí)轉(zhuǎn)為全紅以及后期迅速軟化時(shí)表達(dá)量均較高。沾化冬棗ZjXTH2基因在采后貯藏中呈現(xiàn)先上升后下降的趨勢，在果實(shí)轉(zhuǎn)為全紅時(shí)表達(dá)量最高。研究結(jié)果說明，XTH基因在棗果實(shí)的成熟軟化中可能起著一定的促進(jìn)作用。

關(guān)鍵詞： 棗果實(shí)； XTH基因； 實(shí)時(shí)熒光定量PCR

中圖分類號：Ｓ６６5．1 文獻(xiàn)標(biāo)識碼：Ａ 文章編號：１００９－９９８０?穴２０11?雪０6－998－０7

Cloning and expression analysis of xyloglucan endotransglucosy- lase/hydrolase (XTH) gene in jujube fruit

LV Yan-rong，REN Xiao-lin*

（College of Horticulture， Northwest A F University， Yangling， Shaanxi 712100 China）

Abstract: In order to study the relationship of Xyloglucan endotransglucosylase/hydrolase (XTH) and fruit growth and softening in two jujube （Ziziphus jujuba M.） cultivars， Li jujube and Zhanhua Dong jujube， two partial XTH cDNA sequences were obtained by 3 RACE， and the expression of XTH genes during fruit growth and ripening at the room temperature was investigated by real-time quantitative PCR （RT-qPCR）approach. The results showed that， the two partial XTH cDNA sequences named ZJXTH1 (GenBank accession number: HQ896312) and ZJXTH2 (GenBank accession number: HQ896313) were 776bp， containing 636 bp ORF and coding 212 amino acids. The results of homologous analysis in GenBank demonstrated that the ZJXTH sequences were 68% to 78% identical with those of other plants on the nucleotide sequences and the deduced amino acid sequences. The expression of ZJXTH genes accumulated since 51 days after flowering in both jujube cultivars and was markedly higher during the fruit ripen and storage than the growth period. The ZJXTH1 expression displayed up-down-up trend during the storage， and the maximums appeared in the fruit turning red and rapidly softening period. The ZJXTH2 expression displayed up-down trend during the storage， and the maximum appeared in the fruit turning red period. All these results suggest that the XTH gene might play a promoting role in the jujube fruit ripeness and softening process.

Key words: Jujube fruit； XTH gene； Real-time PCR

果實(shí)的成熟衰老與細(xì)胞壁結(jié)構(gòu)的變化密切相關(guān)，而開花植物的細(xì)胞壁主要由纖維素、半纖維素、果膠和一些結(jié)構(gòu)蛋白組成[1]。木葡聚糖是雙子葉植物初生壁中含量最豐富的半纖維素，這種長鏈的多糖能夠與纖維素微纖絲形成氫鍵，可以對相鄰的微纖絲分子進(jìn)行約束和支撐[2]。改變木葡聚糖的交叉連接結(jié)構(gòu)，可能直接或間接的對纖維素-木葡聚糖交聯(lián)網(wǎng)絡(luò)的松弛產(chǎn)生一定影響[3]，從而引起細(xì)胞壁結(jié)構(gòu)的變化。……