Hormone Pathway Analysis Related to Sex Determination in Melon (Cucumis melo L.) | 与甜瓜性别分化相关植物激素生物合成途径分析

Chinese. 甜瓜性别分化是由多因素构成的一个复杂的网络系统调控，受到多种环境因素及激素水平的影响。本研究利用甜瓜(Cucumis melo L.)WI 998×TopMark 构建重组自交系群体，通过第二代高通量测序技术对F2S6 群体中雌雄异花同株及全雌系植株的转录组测序，比较差异表达基因，分析与性别差异表达相关的植物激素合成途径。结果显示，雌雄异花同株获得77 376条Unigenes，平均长度为435 bp；全雌系转录组测序获得80 825条 unigenes，平均长度为509 bp。比较雌雄异花同株与全雌系转录组，发现共有8 966个基因差异表达，4 296个基因下调，4 670个基因上调。对差异基因进行基因本体论(GO)功能分类，发现2 352条Unigenes 归入到生物学过程，4 107条Unigenes 归入到细胞学过程，2 507条Unigenes 归入到分子功能。差异表达基因共参与121个Pathway，发现赤霉素(gibberellin, GA)合成途径中GA3 -氧合成酶(GA3-ox)(MU3674)、GA7-氧化酶(GA7-ox)(MU36987)、GA2-氧化酶(GA2-ox)(MU13098/MU13099)、GA20-氧化酶(GA20-ox)和GA2-氧化酶(GA2-ox)(MU33020)等基因差异表达；共有38个基因在脱落酸(abscisic acid, ABA)合成途径中差异表达，其中19个上调，19个下调；油菜素内酯(brassinolide, BR)合成途径中，MU22012(cytochrome P450)，MU26893 (cytochrome P450)基因上调，MU56098(cytochrome P450，CYP724B3)，MU76596(CYP724A1)下调。本研究还发现参与甜瓜性别表达，分别与赤霉素、脱落酸、油菜素内酯及玉米素等多种激素合成、信号传导等代谢途径相关。研究结果为分析甜瓜决定性别分化的可能机理，为下一步研究甜瓜性别修饰基因的克隆，提供重要依据。

English. The sex differentiation of melon is a complex system-regulation network, which is effected by different environment factors and level of hormone. In this study, a set of recombinant inbred lines of melon(Cucumis melo L.) was derived by crossing WI 998 with TopMark. The transcript profiles of monoecious lines and gynoecious lines in F2S6 group were acquired using the second-generation high throughput sequencing method, and genes associated with plant hormone biosynthesis pathways were analyzed by comparison of differentially expressed genes, Solexa sequencing and sequence-assembling, the results showed that 77 376 Unigenes were acquired from transcripts of monoecious lines with an average length of 435 bp, and 80 825 Unigenes were acquired from transcripts of gynoecious lines with an average length of 509 bp. Comparing the transcript profiles between monoecious and gynoecious lines, 8 966 genes were deemed as differentially expressed. In these genes, 4 296 genes were down-regulated while 4 670 genes were up-regulated. These genes were classified by gene ontology(GO)-ranking method, 2 352 Unigenes were related to biological process, 4 107 Unigenes were related to cellular process, and 2 507 Unigenes were related to molecular functions. The differential expressed genes participated in 121 pathways, gibberellin biosynthesis pathway, gibberellin3- oxidase(GA3-ox)(MU3674), GA7-ox(MU36987), GA2-ox(MU13098/MU13099), GA20-ox and GA2-ox (MU33020) were differentially expressed. Thirty eight genes expressed differentially involved in abscisic acid biosynthesis pathway, which 19 genes were up-regulated and 19 genes were down-regulated. In brassinolide biosynthesis, MU22012 (cytochrome P450) and MU26893 (cytochrome P450) were up-regulated, and MU56098 (cytochrome P450, CYP724B3) and MU76596 (CYP724A1) were down-regulated. In this study, the sex differentiation was also associated with the biosynthesis and signal transduction pathways of gibberellin, abscisic acid, brassinolide and zeatin. The results provide strong and important basis for the analysis of the possible mechanism of sex differentiation of melon, and for the further research on melon sex-modification genes cloning.