An ms2 male-sterile, female-fertile soybean sharing phenotypic expression with other ms mutants

Genetic and cytological studies of microsporogenesis and microgametogenesis were conducted with a natural male‐sterile, female‐fertile soybean mutant (BR97‐17971) found in an F₄ breeding line of the Brazilian soybean breeding programme. Allele tests with ms Type Collection from USDA/ARS showed that the gene was allelic to ms2. Conventional analysis of microsporogenesis revealed a differential meiotic behaviour from the normal one reported in ms2 male‐sterile plants. Sterile plants have different levels of meiotic abnormalities related to chromosome segregation. Despite segregational abnormalities in the first and second divisions leading to micronuclei formation, the main meiotic cause of pollen sterility was absent or the defective cytokinesis following telophase II. Absent or defective cytokinesis has never been reported in ms2 mutants, but it was reported in the ms1 and ms4 mutants. After telophase II, one to four nucleate microspores underwent degeneration. Cross‐sections of sterile plant anthers showed that, at telophase II, the tapetal cells with large vacuoles degenerated. Despite callose deposition around meiocytes, sterile plants did not form tetrads. They degenerated and collapsed after callose dissolution, forming an amorphous mass. Anthers from male‐sterile plants were shrivelled.     

Identification of allelic variations of puroindoline genes controlling grain hardness in wheat using a modified denaturing PAGE

The amount of long chains (LC) of amylopectin in high-amylose rice is thought to be one of the important determinants of its quality when cooked. A wide range of differences in LC content have been reported in rice varieties, which can be clearly divided into four classes based on LC and apparent amylose content: namely, amylose and LC-free, low or medium-amylose and low-LC, high-amylose and medium-LC, high-amylose and high-LC. However, genetic factors controlling LC content have not been fully understood. Here, we performed quantitative trait loci (QTL) analysis of LC content using 157 recombinant inbred lines (RILs) derived from a cross of a low-LC cultivar, Hyogokitanishiki, and a high-LC line, Hokuriku 142. By analyzing randomly selected 15 RILs, it was shown that high LC content (≥11%) was associated with high setback viscosity (≥200 RVU), and that low LC (≤ 3%) was associated with low setback viscosity (≤ 130 RVU), as measured by a Rapid Visco Analyzer. With setback viscosity as an indicator for LC content, QTL analysis was conducted using 60 DNA markers including a CAPS marker that distinguished Wx a and Wx b alleles coding for granule-bound starch synthase I (GBSSI or Wx protein), the enzyme working for amylose biosynthesis. Only one QTL with a peak log of likelihood score at the wx locus was detected, and no line showing setback viscosity corresponding to the medium-LC class appeared. The fact that wx mutants of Hokuriku 142 lacked LC in their rice starch supports the view that the functional Wx allele is indispensable for LC synthesis in addition to amylose synthesis in rice endosperm. We suggest three possible reasons why no line with medium-LC content was observed. First, the locus (loci) responsible for generation of medium-LC may be located very close to the wx locus and not able to be dissected by the population and DNA markers we used. Second, there may be special QTLs for medium-LC cultivars that do not exist in low- or high-LC cultivars. Third, medium-LC cultivars may have an as-yet unidentified Wx allele with lower capability in LC synthesis compared to the Wx allele in high-LC cultivars.     

广西东兰乌鸡的遗传多样性分析

[目的]了解广西东兰乌鸡的遗传多样性及保种效果,为下一步的种质资源保护和育种研究提供参考依据.[方法]采集片羽东兰乌鸡和丝羽东兰乌鸡的翅静脉血样,提取总DNA,PCR扩增18个微卫星位点并对其基因片段进行扫描,利用PopGen 32生物软件分析测定东兰乌鸡群体的等位基因数(Na)、有效等位基因数(Ne)、杂合度(H)、多态信息含量(PIc),并与其他广西地方品种鸡进行聚类分析.[结果]18个微卫星标记在广西东兰乌鸡群中均表现出较高的多态性,从所检测的80个东兰乌鸡样本中共检测出98个等位基因,每个位点的平均Na为5.44个,Ne为2.78个,PIC为0.5382,H为-0.5963.其中,丝羽东兰乌鸡和片羽东兰乌鸡分别检测到93和98个等位基因,平均每个位点的Ne分别为2.62和2.76个,PI为0.5088和0.5398,H为0.6247和0.5991.聚类分析结果显示,东兰乌鸡与广西三黄鸡、霞烟鸡、南丹瑶鸡的遗传距离(DA)均较远,与其品种的进化、地理分布和选育历史基本相符.[结论]广西东兰乌鸡保种群的遗传变异较大,具有丰富的遗传多样性,其选育潜力较高.     

玉米Opaque-2基因内3个SSR位点的显性等位变异及其对赖氨酸含量的影响

以10个O2O2基因型的普通玉米自交系和3个o2o2基因型的高赖氨酸玉米自交系为材料，用3对O2基因内SSR引物phi112、umc1066和phi057进行PCR扩增产物电泳图谱分析和特异片段序列比较分析，以期了解O2位点显性等位变异对赖氨酸含量的影响。结果表明，玉米phi112、umc1066和phi057三个SSR位点均有丰富的显性等位变异，phi112位点的变异主要发生在其SSR序列的两侧，umc1066和phi057两位点的变异主要表现为SSR序列内部重复数目的变化和点突变。这些变异均对玉米籽粒的赖氨酸含量有影响。还讨论了这些显性等位变异影响O2基因的转录效率及其翻译产物对激活玉米醇溶蛋白合成能力改变的可能机制。     

植物基因资源异境保存遗传抽样策略

遗传资源抽样是指在一定的置信度标准下，抽取的样本能覆盖要研究的目标种或特定地域内群体现有的遗传变异．它是植物基因资源保护研究过程中首先必须要解决的问题，具有十分重要地位．对于一个有效的遗传抽样，必须要同时考虑群体间及群体内的抽样．从样本容量、群体数及实际应用等方面进行较全面的综述．     

Relationship Between Gliadin Alleles and Dough Strength in Italian Bread Wheat Cultivars

Dough strength, as determined by Alveograph W, was studied in Italian bread wheat cultivars grown at several locations over 21 years of testing. Broad sense heritability of Alveograph W was found to range between 0·40 and 0·82, variation in this parameter being affected by genotype×year interactions. Standardised Alveograph W values (Wst) across 40 environments (location–year combinations) were computed for 54 cultivars with reference to the long-term control (cv. Mec), and a quality score based on the Wst value was given to each gliadin allele occurring in at least four of the 54 cultivars analysed. Significant differences in Wst values were observed at theGli-B1,Gli-B2andGli-A2loci. AllelesGli-B1b,Gli-B2candGli-A2bwere significantly related to high gluten strength. An overall quality score based on allelic composition at these loci explained 41% of the observed Wst variation in the 54 cultivars used for the score definition, and 23% to 48% of W value variation in three sets of independent data. The combination of this score with a quality score based onGlu-1alleles coding for highM_rglutenin subunits could explain, on average, about 50% of gluten strength variation.     

甘蓝型油菜粒色遗传的复等位模型假说

通过分析GH06×94005和GH06×A800两组合各世代粒色分离情况,提出复等位遗传模型假说。据此模型,较好地解释了两组合各世代粒色显隐性遗传关系。有关复等位遗传模型假说的应用范围也做了初步讨论。     

Effect of the Y chromosome on testis weight in mice

We investigated the effect of the Y chromosome on testis weight in (B6.Cg-A^y × Y-consomic mouse strain) F₁ male mice. We obtained the following results: (1) Mice with the Mus musculus domesticus-type Y chromosome had significantly heavier testis than those with the M. m. musculus-type Y chromosome. (2) Variations in Usp9y and the number of CAG repeats in Sry were significantly associated with testes weight. The A^y allele was correlated with a reduced testis weight, and the extent of this reduction was significantly associated with a CAG repeat number polymorphism in Sry. These results suggest that Y chromosome genes not only influence testis weight but also modify the effect of the A^y allele in mediating this phenomenon.     

Further characterization of diabetes mellitus and body weight loss in males of the congenic mouse strain DDD.Cg-Ay

The A^y allele at the agouti locus causes obesity and promotes linear growth in mice. However, body weight gain stops between 16 and 17 weeks after birth, and then, body weight decreases gradually in DDD.Cg-A^y male mice. Body weight loss is a consequence of diabetes mellitus, which is genetically controlled mainly by a quantitative trait locus (QTL) on chromosome 4. This study aimed to further characterize diabetes mellitus and body weight loss in DDD.Cg-A^y males. The number of β-cells was markedly reduced, and plasma insulin levels were very low in the DDD.Cg-A^y males. Using a backcross progeny of DDD × (B6 × DDD.Cg-A^y) F₁-A^y, we identified one significant QTL for plasma insulin levels on distal chromosome 4, which was coincidental with QTL for hyperglycemia and lower body weight. The DDD allele was associated with decreased plasma insulin levels. When the DDD.Cg-A^y males were housed under three different housing conditions [group housing (4 or 5 DDD.Cg-A^y and DDD males), individual housing (single DDD.Cg-A^y male) and single male housing with females (single DDD.Cg-A^y male with DDD.Cg-A^y or DDD females)], diabetes mellitus and body weight loss were most severely expressed in individually housed mice. Thus, the severity of diabetes and body weight loss in the DDD.Cg-A^y males was strongly influenced by the housing conditions. These results demonstrate that both genetic and nongenetic environmental factors are involved in the development of diabetes mellitus and body weight loss in the DDD.Cg-A^y males.