基因差异表达与杂种优势形成机制探讨

对杂种优势这一普遍而重要的生物学现象研究虽有百余年的历史, 但其根本机理尚未阐述清楚。继基因组组成差异及基因效应研究之后, 基因表达差异成为探寻杂种优势分子机理新的切入点。旨在通过揭示杂种中等位基因差异表达、杂种与亲本间基因差异表达的调控机制, 来认识杂种优势形成的分子机理, 从而达到指导育种实践的目的。文章概述了杂种等位基因差异表达现象及其产生机理, 总结了杂种与亲本相比所呈现出的加性、显性和超显性等多种差异基因表达模式, 归纳了表达谱研究筛选出的与杂种优势形成有关的基因, 以及某些关键生化代谢途径对杂种优势形成的贡献。但由于杂种优势机理的复杂性, 基因表达研究并没有得出统一的表达模式, 大多数杂种优势基因也不能被归属为同一类别。尽管如此, 基因表达谱研究毕竟迈出了解析杂种优势形成复杂基因表达网络的第一步, 随着表达谱技术和生物信息学的不断更新和发展, 杂种优势形成的分子机理有望在基因表达层面上取得突破。     

A diallel analysis of heterosis in elite hybrid rice based on RFLPs and microsatellites

Hybrid rice has contributed significantly to the dramatic increase of rice production in the world. Despite this, little attention has been given to studying the genetic basis of heterosis in rice. In this paper, we report a diallel analysis of heterosis using two classes of molecular markers: restriction fragment length polymorphisms, (RFLPs) and microsatellites. Eight lines, which represent a significant portion of hybrid rice germ plasm, were crossed in all possible pairs, and the F₁s were evaluated for yield and yield component traits in a replicated field trial. The parental lines were surveyed for polymorphisms with 117 RFLP probes and ten microsatellites, resulting in a total of 76 polymorphic markers well-spaced in the rice RFLP map. The results indicated that high level heterosis is common among these crosses: more than 100% midparent and 40% better-parent heterosis were observed in many F₁s, including some crosses between maintainer lines. Heterosis was found to be much higher for yield than for yield component traits, which fits a multiplicative model almost perfectly. Between 16 and 30 marker loci (positive markers) detected highly significant effects on yield or its component traits. Heterozygosity was significantly correlated with several attributes of performance and heterosis. Correlations based on positive markers (specific heterozygosity) were large for midparent heterosis of yield and seeds/panicle and also for F₁ kernel weight. These large correlations may have practical utility for predicting heterosis.     

Genetic analysis and gene mapping of a new rolled-leaf mutant in rice (Oryza sativa L.)

To understand the development of rice leaf blades,we identified a new rolled-leaf mutant,w32,from indica cultivar IR64 through EMS mutagenesis. The mutant showed a stable rolled-leaf phenotype throughout the life cycle. Two F2 populations were developed by crossing w32 to cultivar IR24 and PA64. Genetic analysis showed that the rolled-leaf phenotype was controlled by a single recessive gene. To determine the location of the gene,bulked segregant analysis was carried out using mutant and wild-type DNA pools ...     

水稻长穗颈基因eui紧密连锁SSR标记获得

02428h是从半矮秆材料02428体细胞培养后代中发现的隐性高秆突变体, 其株高性状由1对长穗颈基因eui和1对半矮秆基因sd-1共同控制。以02428h与半矮秆材料南京11杂交的F₂为作图群体, 利用Gramene公布的SSR标记和根据NCBI中的BAC序列自己新开发的SSR标记, 将eui基因定位在第5染色体上的RM3673和RM0012之间, 两侧遗传距离分别为0.3 cM和1.0 cM, 为该基因的分子标记辅助选择奠定了基础。     

Structure, expression pattern and chromosomal localization of the rice Osgrp-2 gene

The plant cell walls comprise various enzymes and several kinds of structural proteins. In addition to the structural roles, the structural cell wall proteins also function in altering the physi-cal properties of cell walls as cells grow, divide and differentiate, and in repairing of cell walls after infection or wounding[1,2]. Plant structural cell wall proteins may be divided into four main classes: extensins, proline-rich proteins (PRPs), arabinogalactan proteins (AGPs) and glycine-rich p…     

Identification of a gibberellin-induced gene in deepwater rice using differential display of mRNA

Differential display of mRNA was employed to identify gibberellin (GA)-regulated genes in deepwater rice. One of the first differentially displayed products identified was shown to be ten-fold induced after start of GA treatment. The sequence of the clone shows complete amino acid identity with histone H3, and its increased mRNA level correlates with the onset of DNA synthesis. We also identified a gene whose expression pattern did not change over the course of treatment with GA and can be used as standard to correct for loading differences on northern blots.     

DNA uptake by imbibition and expression of a foreign gene in rice

Uptake of DNA by imbibition of dry and viable rice ( Oryza sativa L.) embryos from a DNA solution and expression of a foreign gene were detected using two different vectors contaíning gusA (β-glucuronidase) and hpt (hygromycin phosphotransferase) as reporter genes. The frequency of transient expression of gusA and hpt genes using the CaMV35S promoter was about 30 to 50%. The main sites of gusA gene expression were meristems of roots and vascular bundles of leaves. Also, DNA uptake, integration and expression of the hpt gene in selected rice were investigated by various PCR methods and Southern blot analysis of genomic DNA. It was shown that the hygromycin phosphotransferase (HPT) DNA was present in the rice genome in an integrated form and not as a plasmid form.