小麦杂交种与亲本之间穗下节间基因差异表达分析

Differential Gene Expression in Uppermost Internode between Wheat Hybrid and Its Parents

以株高和穗下节间长度表现杂种优势的小麦杂交组合矮9×冀矮8号的杂种及其亲本为材料,应用cDNA-AFLP技术分析杂种、亲本的穗下节间基因差异表达情况。分离差异表达基因段后,对其克隆、测序并在GenBank进行Blast-x分析和功能推测,发现差异表达的基因包括分别受赤霉素和细胞分裂素诱导表达、与细胞分裂有关的基因cdc2和PAS1基因,它们在小麦杂种节间中分别特异表达和偏高亲表达。另有一个与细胞快速膨大有关的液泡质子泵H+-PPase基因在杂种中偏高亲表达。其他差异表达的基因包括蛋白激酶等与植物信号传递相关基因、与物质代谢相关的基因、参与基因转录调控的基因、与泛素参与的蛋白降解相关的基因等。小麦杂交种与亲本的穗下节间,大量基因涉及细胞分裂、膨大和物质代谢、转录调控等过程,初步推测它们的差异表达可能与穗下节间及株高杂种优势形成有关。

Heterosis is defined as the advantage of hybrid performance over its parents in growth and productivity. Previous studies showed that differential gene expression in hybrids and their parents is responsible for the heterosis. Plant hormones, especially GAs are found to be related to heterosis in development of shoot and plant height. However, information on systematic identification and characterization of the differentially expressed genes in shoots of hybrid and their parents are not found, and molecular evidence for the contribution of plant hormone to plant heterosis are also absent. The purpose of this paper was to investigate the differential gene express in stems of hybrid and their parents, and further, to investigate the possible role of genes participating hormone signaling in the formation of heterosis of plant stem. Using a wheat cross combination that exhibited vigorous heterosis in plant height, the differential gene expression in upper-most internode of wheat hybrids and their parents was analyzed by cDNA-AFLP. Ninety-eight differentially expressing cDNA fragments were obtained, which were sequenced and analyzed by Blast-x. Reverse Northern hybridization was performed in order to test the expression pattern of isolated ESTs in hybrid and their parents. The differentially expressed genes included a cdc2 gene and a PAS1 gene, which were induced by GAs and CTKs respectively and participated in plant cell division. The cdc2 gene was up-regulated in hybrid while the expression of PAS 1 in hybrid was near the higher parent. The differentially expressed genes also included kinase participating in signal transduodon, genes involved in metabolism and genes related to transcription regulations. It can be inferred that numerous genes were differentially expressed in the upper-most internode of hybrids and their parents, including genes participating in cell division and cell expansion, kinase related to signal transduction and so on. Reverse Northern blot analysis indicated that the expression pattern in our cDNA-AFLP analysis is credible. Since it has been much reported that genes participating in cell division and cell expansion are involved in plant stem growth and elongation, and genes that participate in gibberellins signals have been proved to be up-regulated in wheat hybrid and contributed to heterosis in wheat plant height, it can be modestly speculated that the differential expression of genes involved in phytohormone signals may be related to heterosis in wheat intenode elongation and plant height.