石刁柏离体培养快速繁育的研究──Ⅰ外植体基因型的差异

对国外引进４个主要品种和一个全雄试管苗品系在同一培养条件下离体培养的差异进行了研究。结果表明，５个基因型均能形成愈伤组织，但生长量不同，同一基因型不同组织愈伤组织生长速率为：茎段＞茎尖＞腋芽＞拟叶；幼芽分化数差异显著，愈伤组织途径最多达１９个，最少为１０个；直接分化幼芽最多１２个，最少仅４个；根系诱导显著不同，平均每株正常根数最多１２条，最少４条。随着继代培养次数增加，各基因型器官分化能力逐渐降低，尤以根诱导最为显著，其中２个品系受影响较小。     

不同品系鸡淀粉酶同工酶的遗传研究

采用聚丙烯酰胺梯度凝胶电泳法研究了罗斯褐、星杂283、星杂579、艾维茵和印第安河等4个品系鸡血清以及星杂288、艾维茵、印第安河鸡羽毛的淀粉酶同工酶的遗传控制谱型、表型频率和基因频率。鸡的血清和羽毛淀粉酶同工酶谱分为A、C、D,B、C、D和A、B、C、D 3种类型的酶区带,并显示AA、AB、BB的表型特征,各品系鸡以AB表型频率最高;其次,罗斯褐、艾维茵和印第安河鸡为AA型;星杂238和星杂579鸡为BB型。显示A基因(Amy-1A)频率高的是艾维茵、印第安河和罗斯褐鸡,星杂579、星杂288则显示基因(Amy-1 B) 频率高。同一品系鸡的父母代(母系)和商品代(母鸡)之间的淀粉酶同工酶表型频率和基因频率者未见差异(P>0.05)。本试验建立了鸡羽毛淀粉酶同工酶的检测方法,此方法简便,测定结果与血清样品比较也未见差异(P>0.05),故可用羽毛代替血清测定鸡的淀粉酶同工酶。     

河南省14个不同大豆基因型联合试验研究

用Francis和Kannenberg(1978)提出的平均数和变异系数分组法,对河南省14个不同大豆基因型联合区试中18个环境的资料进行了稳产性分组。并把14个基因型分为以下四类:(1)高产稳产类型(2)高产不稳产类型(3)低产稳产类型(4)低产不稳产类型。通过联合方差分析和显著性检验,发现周84—2和辐803产量显著地高于其余12个品种,二者本身没有显著差异,同属第一位。但周84—2稳产性不及辐803,特别适应区数也不及辐803多。周84—2在特别适应区种植,增产潜力有可能大于其它基因型。第一种类型中的其余4个基因型,都显著地比两个对照增产,稳产性也优于两个对照和84—2,可作为辐803和周84—2的搭配种使用。     

DNA标记技术研究进展

本文综述了几种DNA分子标记技术：RFLP，小卫星与微卫星指纹技术，RAPD，AFLP，DNA芯片生物技术等的原理，及其在实际运用中的优缺点。     

Study on the Strategies of Genotype Imputation

Genomic data is more and more widely used in livestock breeding. Genotype imputation is an important tool to handle missing values in genotypic data, and the quality of imputation results directly affects the subsequent analysis. To obtain good imputation results, a comprehensive imputation strategy needs to be formulated. We studied on the effects of several factors on genotype imputation by simulation. The factors included reference population size, genetic relationship (distance) between the target population and the reference population, the number of target sites (proportion), the minimum allele frequency (MAF), and the imputation algorithm. The results showed that the number of target sites was the main factor affecting the genotype imputation, and it showed significantly positive correlation with the quality of imputation(P<0.05). The reference population size was the main factor affecting the imputation error rate in Beagle5.1. Correspondingly, the number of target sites was the main factor affecting the imputation error rate in Minimac4. Genetic distance between the target population and the reference population had a more significant effect on the imputation quality of Beagle5.1 than Minimac4. In general, the imputation error rate increased as the increases of MAF in a site. When the number of individuals in the reference population was small and the number of target sites was large, the speed of Minimac4 was superior to Beagle5.1, but there was a reverse trend as the reference population size increased. On the premise of ensuring the imputation quality, Beagle5.1 had relatively lower requirements for the above factors. In contrast, when the number of target sites was low and reference population size was large, the imputation effect of Beagle5.1 was better, while Minimac4 was more suitable for the imputation of a small reference population size and a higher number of target sites. In this study, different strategies were formulated for different imputation purposes, and the study results would provide a reference for genotype imputation.     

农业类高校在江西新农村教育信息化建设中的作用

分析了江西农村信息化教育的发展现状及存在问题,提出了农林类高等学校在新农村建设中应承担的责任,探讨了农林院校在农村地区开展教育信息化的优势和所能发挥的作用。     

基因型和培养因子对诱导草莓叶片再生芽的影响

以草莓品种Ｍ１４叶盘为外植体,建立了一个有效的、高频率的芽再生系统。通过对基本培养基、叶龄、基因型、暗培养处理以及激素组合等因子的研究,探讨了这些因子对草莓叶盘不定芽诱导的影响。在ＭＳ基本培养基附加３．０ｍｇ／ＬＢＡ和０．２ｍｇ／Ｌ２．４－Ｄ的培养基上,Ｍ１４叶盘不定芽再生频率达９４．４４％,平均每叶盘再生芽率１０．５６个。暗培养处理不能提高Ｍ１４叶盘的芽再生频率。１４～３０ｄ叶龄的叶盘有较高芽再生频率。Ｍ１４叶盘再生芽系统可用作草莓的微繁殖系统和基因转化的受体系统。     

脱落酸对不同基因型小麦抗旱性的影响

脱落酸（ＡＢＡ）是植物内源激素,参与调节许多与植物抗旱性有关的生理生化反应,但外源ＡＢＡ对植物抗旱性的影响与植物的基因型和ＡＢＡ的施用方法有关。停水７ｄ后,根施ＡＢＡ和叶施ＡＢＡ提高所有４个供试小麦品种的绿叶面积和降低所有品种的叶绿素含量。根施ＡＢＡ提高３个品种叶片相对含水量,叶施ＡＢＡ只提高１个品种相对含水量。根施ＡＢＡ对小麦品种Ｋｉｔｅ和Ｂａｎｋｓ的复水成活率无影响,但降低Ｋａｒｃｈｙｉａ和Ｃ－３０６的复水成活率,叶施ＡＢＡ降低所有４个品种的复水成活率。相关分析表明干旱复水成活率与幼苗全株干重相关显著,与假茎干重相关极显著。     

小麦抗涝的基因型差异对逆境胁迫的比较生理学效应

研究了抗涝小麦品种华麦８号和不抗涝小麦品种鄂恩１号对涝渍胁迫的比较生理学效应。结果表明：在淹水条件下,华麦８号的叶绿素和脯氨酸含量、酶促自由基清除系统的活性、根系活力均显著高于鄂恩１号,与之相反,鄂恩１号的丙二醛（ＭＤＡ）含量却明显高于华麦８号。这揭示抗涝基因型品种具有显著的生理表型效应。     

Changes in race structure of Canadian populations ofPhytophthora infestans based on specific virulence to selected potato clones

Summary A collection of 80 isolates ofPhytophthora infestans, representing multilocus genotypes of the pathogen found in Canada from 1994 to 1996, was screened on a series of nine differential potato host cultivars to determine the physiological race of the isolates. A total of 28 pathotypes were found among the 11 genotypes present in the collection. There was a significant increase in the complexity of pathotypes from 1994 to 1996 which reflected the displacement of the US-1 genotype (mean of 2.2 host differentials infected) by the US-8 genotype (mean of 8.1 host differentials infected). Eighteen of the US-8 isolates could overcome all nine of the resistance genes tested. Virulence genes which overcame host resistance conferred by R8 were the rarest in the populations studied. The predominance of complex populations ofP. infestans in Canada implies that the introduction of cultivars with specific R genes for resistance would be an ineffective control measure. AAFC Contribution No. 901