分蘖型谷子资源的表型和遗传多样性分析

本研究选用了来自国外及国内的68份分蘖型谷子进行了表型及遗传多样性分析。表型分析表明,质量性状以绿鞘、白谷黄米、圆锥穗、松散穗码居多,数量性状变异系数除出谷率较小外,其他性状表现了丰富的遗传变异,来自山西的小软谷单株穗重、单株穗粒重、千粒重均为最高,而来自黑龙江的大青谷单株穗粒重、出谷率、千粒重均为最低。遗传多样性分析结果表明,77对引物共检测出202个等位位点,每对引物可检测到1~6个位点不等,平均为2.62个;77对引物多态性信息含量(PIC)在0.0283~0.6974之间,平均多态性信息量(PIC)为0.4169,68份材料间的遗传相似系数变化范围为0.59~0.96,平均值为0.68。利用软件NTSYSpc 2.10的UPGMA聚类方法对68份谷子分蘖材料进行了聚类,这些材料被划分为4个类群,即Ⅰ、Ⅱ、Ⅲ和Ⅳ。Ⅰ类群主要来自西北地区谷子分蘖种质,Ⅱ类群主要来自国外谷子分蘖种质,Ⅲ类群包括华北、华东和东北的谷子分蘖种质,Ⅳ类群仅包括一个种质。结合表型鉴定出10份优势谷子分蘖种质。这些结果揭示68份谷子分蘖种质遗传多样性较好,研究结果为挖掘谷子分蘖优良基因及谷子分蘖育种提供理论依据。     

普通菜豆种质资源表型鉴定及多样性分析

对646份普通菜豆核心种质在贵州毕节进行了表型鉴定,结果表明,普通菜豆具有丰富的形态性状多样性。总变异数为367,平均遗传丰富度为8.34,变异范围2~31;遗传多样性指数为0.63,变异范围为0.02~0.91。通过多变量的主成分分析,前3个主成分的贡献率较大,分别为17.73%、15.35%和11.33%。依据表型鉴定数据信息,将供试种质聚类并划分为4组。Ⅰ组的遗传多样性较高,主要为直立有限的大粒资源,大多资源属于安第斯基因库;Ⅱ组的遗传多样性最低,为直立无限生长习性的小粒资源,属于中美基因库;Ⅲ组的遗传多样性最高,主要以蔓生无限为主,包括小部分直立无限和匍匐无限的资源;Ⅳ组的遗传多样性较低,为蔓生无限生长习性、株高最高、分枝数最少的资源。筛选到大粒、多荚、长荚、宽荚等具有特异性状的种质资源35份。     

Genetic diversity assessment in Somali sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench) accessions using microsatellite markers

In the north-western region of Somalia, bordering Ethiopia, sorghum represents an important resources for human and animal nutrition. The critical situation of Somalia is threatening the preservation of this valuable resource and it becomes urgent to develop a strategy of correct evaluation of the sorghum germplasm in order to promote conservation and preservation programs. Microsatellites, also known as Simple Sequence Repeats (SSRs), are reproducible molecular markers useful in assessing the level of genetic diversity of plants. A total of 5 sorghum SSR-specific primer pairs were used to assess the genetic diversity of Somali sorghum landraces. Extensive variation was found at the microsatellite loci analysed, except for a locus that resulted in a monomorphic for some accessions. Considerable differences were found between total and effective number of alleles indicating non uniform allele frequency. Moreover allele frequency at a single locus significantly changed among accessions. Total gene diversity calculated for each locus ranged from 0.44 to 0.79. Most of the genetic diversity occurred within accessions demonstrating that accessions are not under selection processes and/or there is a continuous exchange of genes between sorghum populations. In any case, the patterns of clustering were significantly affected by the presence/absence of some alleles with high discriminant weight. Accessions Carabi, Abaadiro, Masego Cas and Masego Cad represent distinct genotypes confirming finding observed in previous phenotypic studies. The results highlight the central role of local farmers in maintaining and shaping local germplasm.     

<Emphasis Type="Italic">Ds</Emphasis> insertion mutagenesis as an efficient tool to produce diverse variations for rice breeding

The availability of diversified germplasm resources is the most important for developing improved rice varieties with higher seed yield or tolerance to various biotic or abiotic stresses. Here we report an efficient tool to create increased variations in rice by maize Ac/Ds transposon (a gene trap system) insertion mutagenesis. We have generated around 20,000 Ds insertion rice lines of which majority are homozygous for Ds element. We subjected these lines to phenotypic and abiotic stress screens and evaluated these lines with respect to their seed yields and other agronomic traits as well as their tolerance to drought, salinity and cold. Based on this evaluation, we observed that random Ds insertions into rice genome have led to diverse variations including a range of morphological and conditional phenotypes. Such differences in phenotype among these lines were accompanied by differential gene expression revealed by GUS histochemical staining of gene trapped lines. Among the various phenotypes identified, some Ds lines showed significantly higher grain yield compared to wild-type plants under normal growth conditions indicating that rice could be improved in grain yield by disrupting certain endogenous genes. In addition, several 1,000s of Ds lines were subjected to abiotic stresses to identify conditional mutants. Subsequent to these screens, over 800 lines responsive to drought, salinity or cold stress were obtained, suggesting that rice has the genetic potential to survive under abiotic stresses when appropriate endogenous genes were suppressed. The mutant lines that have higher seed yielding potential or display higher tolerance to abiotic stresses may be used for rice breeding by conventional backcrossing combining with molecular marker-assisted selection. In addition, by exploiting the behavior of Ds to leave footprints upon remobilization, we have shown an alternative strategy to develop new rice varieties without foreign DNA sequences in their genome. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparative analysis of microsatellite DNA polymorphism in landraces and cultivars of rice

Genetic polymorphisms of ten microsatellite DNA loci were examined among 238 accessions of landraces and cultivars that represent a significant portion of the distribution range for both indica and japonica groups of cultivated rice. In all, 93 alleles were identified with these ten markers. The number of alleles varied from a low of 3 or 4 at each of four loci, to an intermediate value of 9–14 at five loci, and to an extra-ordinarily high 25 at one locus. The numbers of alleles per locus are much larger than those detected using other types of markers. The number of alleles detected at a locus is significantly correlated with the number of simple sequence repeats in the targeted microsatellite DNA. Indica rice has about 14% more alleles than japonica rice, and such allele number differences are more pronounced in landraces than in cultivars. The indica-japonica differentiation component accounted for about 10% of the diversity in the total sample, and twice as much differentiation was detected in cultivars as in landraces. About two-thirds as many alleles were observed in cultivars as in landraces; another two-thirds of the alleles in the cultivar group were found in modern elite cultivars or parents of hybrid rice. The majority of the simple sequence repeat (SSR) alleles that were present in high or intermediate frequencies in landraces ultimately survived into modern elite cultivars and hybrids. The greater resolving power and the efficient production of massive amounts of SSR data may be particularly useful for germplasm assessment and evolutionary studies of crop plants.     

胶东半岛野生迎红杜鹃种质资源研究

迎红杜鹃(Rhododendron mucronulatum)耐寒、开花早、花量大,极富观赏性,但尚未在园林中得到广泛应用。本研究采用样地法,详细调查了崂山、牙山等5个山区的野生迎红杜鹃资源,对迎红杜鹃的分布范围、群体大小、生长环境、开花习性、花期花色、土壤理化性质等进行了细致的观测记录。结果表明,迎红杜鹃在胶东半岛有广泛分布,多位于海拔100~1100 m之间区域,主要为大面积群体分布;生长环境多样,阳坡、阴坡、山顶、溪谷、岩缝均可生长,以阴坡为主;其伴生植物种类较多,群落结构稳定;迎红杜鹃开花早,开花量大,花色均为红紫色系,同一色系中变化较大;不同山区的群体株高、冠幅、花量存在较大差异,而花径差异较小;不同山区的土壤有机质及氮磷钾含量差异较大。上述结果明确了胶东半岛地区野生迎红杜鹃的种质资源分布和生长环境特点,为其合理利用提供了科学依据。     

葫芦科蔬菜种质资源对南方根结线虫的抗性评价

根据不同种质的来源地、农艺性状等背景信息,从国家蔬菜种质资源中期库中选取具代表性的444份主要瓜类作物地方品种,分属葫芦科7个属的13个种或变种,采用病土接种法进行苗期根结线虫抗性鉴定,得出了不同葫芦科作物对南方根结线虫的抗性分布范围。忽略基因型差异,不同作物的平均病级指数从小到大的顺序为:冬瓜、西瓜、丝瓜、节瓜、苦瓜、越瓜、甜瓜、菜瓜、瓠瓜、黄瓜、中国南瓜、印度南瓜、美洲南瓜。通过抗性鉴定,共获得27份抗根结线虫种质(病级指数1~2),包括12份冬瓜、3份苦瓜、7份丝瓜和5份西瓜。     

奥利亚罗非鱼与尼罗罗非鱼rDNA内转录间隔区序列特征

核糖体DNA内转录间隔区(internal transcribed spacers,ITS)是经常被用作种和种群水平系统研究的分子序列.本文分离了奥利亚罗非鱼(Oreochromis aureus)、尼罗罗非鱼(O.niloticus)内转录间隔区,包括部分185序列,ITS1、5.8S、ITS2全序列及部分28S序列.4尾奥利亚罗非鱼的10个克隆序列分析表明,其存在长度不同的a、b两种类型ITS1.a型长为536 bp,GC含量为69.96%;b型长为520 bp,GC含量为69.04%～69.42%.4尾尼罗罗非鱼的10个克隆序列分析表明,其只存在a型ITS1,长为536～540 bp,GC含量为69.42%～70.19%.与b型ITS1相比,a型ITS1在16～31 nt有16 bp片段(GGCCCGCCTCGGCGC)的插入.奥利亚罗非鱼和尼罗罗非鱼共20条ITS序列中,5.8S长度均为157 bp,GC含量为56.69%～57.96%;ITS2为408 bp,GC含量为72.79%～74.26%.奥利亚罗非鱼和尼罗罗非鱼ITS区序列相似性高达98.2%,表明这两种罗非鱼亲缘关系很近.此外,本文对14尾奥利亚罗非鱼、15尾尼罗罗非鱼以及15尾奥尼罗非鱼[O.aureus(♂)×O.niloticus(♀)]ITS1的扩增结果显示,奥利亚罗非鱼均有a、b两种类型ITS1;15尾尼罗罗非鱼中1尾为a、b两类型ITS1,14尾为a型ITS1;15尾奥尼罗非鱼中则有6尾具有a、b两类型ITS1,9尾为单一的a型ITS1.分析表明,奥利亚罗非鱼在ITS1这个位点一致性高,但尼罗罗非鱼中有1尾混杂了奥利亚罗非鱼的基因,同时也说明分子生物学手段应用于种质鉴定比形态学手段更为精确.     

果桑资源研究利用现状与展望

我国保存有桑树种质资源近3000份,其中可作果桑用的资源超过60份.已对桑果的营养成分、桑椹红色素及果桑的栽培管理技术进行了比较全面的研究,开发出桑果饮料、罐头、桑椹膏、桑椹酒等产品.以桑椹为主要原料的防病保健方剂在我国民间广泛应用,但对桑果药理作用的研究还处于初期阶段.今后应加强果桑资源的收集、整理、鉴定及改良创新,加强桑椹药理作用的研究,加快桑果产品的开发,实现桑果综合利用的产业化.     

云南烟草品种资源"九五"研究进展

1996～2000年云南省收集并鉴定评价烟草国内品种(系)60个,国外品种(系)90个,繁殖种子268份进行保存.通过多年鉴定评价筛选出优异种质K346、RG11、RG17等在云南省和全国范围内推广使用.同时,通过对烟草种子超干燥保存及其相关技术的研究,使烟草种子能够安全而长期地保存.烟草品种资源信息管理系统的建立使烟草品种资源研究工作迈向合理化、系统化、规范化的轨道.