水稻种质资源萌发期与孕穗期耐冷性鉴定

目的筛选耐寒性水稻品种。方法以广泛代表性的14个亚洲国家187个水稻核心种质为研究对象,根据种内群体关系和地理位置将其分为4个平行组;分别对4个平行组的三叶期幼苗进行4 ℃低温处理,时间梯度设为24、36、48和60 h,7 d缓苗期后统计其秧苗黄叶率并鉴定耐寒等级。结果根据黄叶率百分比可以精准鉴定水稻的5个耐寒等级,且粳稻的耐寒性普遍比籼稻强。11个强耐寒品种主要分布于高纬度或高海拔地区。4 ℃处理24和36 h后的黄叶率在不同品种间呈现丰富多样性,该耐寒处理方式获得的表型性状适合全基因组关联分析。结论品种之间耐寒性的差异不仅由遗传因素决定,还与其地理分布和当地种植策略相关。本研究初步筛选出11个苗期耐寒水稻品种,可为耐寒种质资源的遗传改良和分子育种提供参考。     

水稻基因组进化的研究进展

介绍了近年来在水稻基因组进化方面的研究进展,主要内容包括:水稻的核基因组至少经历了2次基因组复制过程,并从最初5条染色体形成了12条染色体;水稻籼粳两个亚种的分化估计发生在距今20～40万年前;在水稻驯化的研究方面,一方面克隆了一些控制重要驯化性状的基因,另一方面通过基因组分析发现了一些快速进化的基因组区段;片段复制、串联重复和逆转录转座等基因复制方式在水稻基因家族的物种特异性扩张方面起到了重要作用.通过整合以上研究成果,初步揭示了水稻基因进化的基本特点,为水稻功能基因组学和分子设计育种的进一步研究提供了新的切入点.     

A draft sequence of the rice genome (Oryza sativa L. ssp. indica)

We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.     

A draft sequence of the rice genome (Oryza sativa L. ssp. japonica)

The genome of the japonica subspecies of rice, an important cereal and model monocot, was sequenced and assembled by whole-genome shotgun sequencing. The assembled sequence covers 93% of the 420-megabase genome. Gene predictions on the assembled sequence suggest that the genome contains 32,000 to 50,000 genes. Homologs of 98% of the known maize, wheat, and barley proteins are found in rice. Synteny and gene homology between rice and the other cereal genomes are extensive, whereas synteny with Arabidopsis is limited. Assignment of candidate rice orthologs to Arabidopsis genes is possible in many cases. The rice genome sequence provides a foundation for the improvement of cereals, our most important crops.     

从水稻基因组序列中挖掘生物信息

重点介绍了在水稻基因组序列分析方面取得的几项最新研究结果.内容主要包括:水稻基因组被证实曾发生过全基因组倍增;水稻基因组大小变化的趋势;水稻籼粳亚种的分化时间比以前估计的100万年前要迟得多;对水稻基因产生GC含量负梯度现象的解释.     

高寒山区水稻旱种高产栽培

水稻旱种是在无灌溉条件的地方,靠土壤水分和天然降水种植水稻的一种节水栽培方式.