中文摘要：

为了解铁高效基因型小金海棠抗缺铁的分子机制,对与铁运输相关的YSL基因进行了克隆与分析。分析苹果的EST库得到一个686 bp的YSL基因片段。经3-′RACE及后期拼接得到1 500 bp的该基因的3′端序列。其预测蛋白含10个跨膜区,与拟南芥AtYSL7基因同源性达71%,命名为MxYSL7。RT-PCR及Northern分析表明,小金海棠的该基因只在地上部分表达：在茎与成熟叶中,随着低铁处理时间的延长,该基因表达量减少;随着高铁处理时间的延长,该基因表达量增多。新叶中的表达趋势与茎和成熟叶中的趋势正好相反。讨论了MxYSL7在小金海棠体内铁营养代谢中的作用。认为MxYSL7可能参与了体内铁在木质部和韧皮部的运输过程,并参与铁在体内的解毒过程。

英文摘要：

A 686 bp YSL gene fragment was obtained by analyzing EST data for apple. A complete 3′ sequence consisting of 1 500 nucleotides was obtained by RACE method and the predicted amino-acid sequence included 10 putative membrane-spanning domains. The homology of the encoding protein and AtYSL7, named MxYSL7, was up to 71%. The result of semi-quantitative RT-PCR and Northern analysis showed that MxYSL7 was expressed only in the above area. The expression was down-regulated in stems and mature leaves with iron deficiency treatments but upregulated with excess iron treatments. Young leaves had an opposite expression model. The role of MxYSL7 in iron metabolism was discussed. We suggest that the MxYSL7 might transport iron in xylem and phloem and take part in the detoxification of excessive iron.