Genetic characteristics of self fertility in highbush and half-high blueberries

Summary Parents and ten progeny from each of ten controlled crosses, and thirteen progeny from G65 x Ashworth were self and outcross pollinated to study the inheritance of self fertility and the associations between self fertility and zygotic inbreeding levels in highbush and half-high blueberry genotypes. Reductions in self fertility were apparently a response to increased inbreeding. Both percent fruit set and seeds per pollination were negatively associated with family zygotic inbreeding coefficients. Although inbreeding depression was responsible for much of the observed self fertility responses, an environmental component was apparent as well. A continuous distribution of self fertility levels among the G65 x Ashworth progeny provided little evidence for simple inheritance of this trait. Estimates of heritability were not significant and some evidence of specific combining ability was detected, indicating that parental self fertility was not predictive of the self fertility of the progeny in this study. Variation for self fertility including high levels in some individuals indicates a potential level of self fertility which could be incorporated into future selections and cultivars.     

Inbreeding depression in garden and glasshouse chrysanthemums: germination and survivorship

Summary Sixty-six chrysanthemum (Dendranthema grandiflora) inbred selections, noninbred cultivars and hybrids, and D. makinoi were the base populations from which up to three generations of inbreds were obtained using multiple plant descent. Each parent possessed pseudo-self compatibility (PSC), which allowed seed set following self pollination. Rapid-generation cycling (laboratory seed ripening to heart stage and subsequent embryo rescue) reduced generation time and minimized confounding maternal with zygotic inbreeding depression during post heart-stage seed development. Selection criteria were male/female fertility and PSC. Two stages of the life cycle were chosen to evaluate inbreeding depression: germination (seed development to germination) and survivorship (fertile individuals at anthesis). PSC was environmentally interactive and genotype dependent, causing variable levels of self seed set between and within populations and generations. By the end of the second generation, families from all noninbred cultivars, D. makinoi, and one F₁ hybrid were eliminated from the experiment due to self incompatibility and/or inbreeding depression. Post-germination inbreeding depression was severe in several advanced inbreds. Inbred progeny of most F₁ or F₂ hybrids expressed less or equal amounts of inbreeding depression compared to advanced inbreds. Linear regression coefficients for either germination or survivorship on percent homozygosity were negative. Correlation coefficients between percent germination and survivorship (as a percent of seed set) were highly significant for Minnesota inbreds (r=0.67, P0.002) and hybrids (r=0.67, P0.006). The correlation coefficient was higher when percent germination and survivorship (as a percent of germinated seedlings) were compared (r=0.95, P0.001).Abbreviations F Fisher's Coefficient of Inbreeding - IBD Inbreeding Depression - PSC Pseudo-self Compatibility - RGC Rapid Generation Cycle - SI Self Incompatibility     

自推进耕耘机械研究现状与分析

自推进耕耘机械与传统的拖拉机－农具机组相比，其结构简单，机组短，效率高，适合在水田和特殊地块作业，本文结合机滚船，自推进旋耕机和工作轮驱动型中耕机介绍了自推进耕耘机械的原理，特点及研究现状，分析了有关技术问题以及进一步研究的方向。     

甘蓝和油菜中类硫氧还蛋白THL2基因的克隆与序列分析

 采用PCR和RT-PCR方法，对甘蓝和油菜的基因组DNA和柱头总RNA进行扩增，获得了类硫氧还蛋白THL2的DNA和cDNA。序列分析首次表明THL2基因有两个内含子，并且在油菜和甘蓝中的大小不同。进一步分析表明，油菜和甘蓝中THL2 DNA序列的同源性为96％。     

白菜型油菜雄性不育材料的发现和育性观察

1989年3月,我们在油菜甘白种间杂交(81008X托品)F_4代白菜型油菜品系中,发现了雄性不育株。经过两年多的观察研究,其测交和回交后代无育性分离,现有白菜型油菜品仲中存在着保持和恢复基因。初步认为,该不育材料属于核质互作的细胞质不育类型。该不育材料在盛花前总不育率为98.76%,盛花后育性有变化。与波里马不育系高温敏感型相比,其育生变化除高温因素外,对光照长度是否也有一定的诱导作用,或需要一定的积温后才能导致育性发生变化进行了讨论。后期可育株自交和兄妹交结实指数分别为0.044和0.090,低于自交不亲和结实指数1.0的标准,剥蕾自交结实指数也仅5.133。根据其雄性不育和自交不亲和双重性质、作者认为,该不育材料用于配制杂种,纯度可能优于白菜型油菜自交迟钝系和标志性状杂种。     

甘薯近缘三倍体杂种2n花粉发生和利用的研究

将甘薯的近缘野生种Ipomoea trifida(2x)与I.littoralis(4x)杂交，得到三倍体杂种。在三倍体杂种无性系中观察到可被醋酸洋红染色的可育大粒花粉（2n花粉），该花粉频率与花粉母细胞四分体时期的二分体频率呈显著正相关。以三倍体2n花粉系为父本与甘薯杂交，观察到花粉萌发、受精、胚发育和结实，但结实率很低，且种子大多没有生活力。本研究表明，其主要原因有：柱头花粉附着量和花柱中花粉管较少，受精后合子停止发育和胚未能发育成熟。用植物生长调节剂处理对克服子房水平的上述不亲和性有效。     

玉米异交不亲和基因Ga1-S的蛋白质组分析

为了研究玉米异交不亲和的蛋白表达机制,以玉米(Zea mays L.)异交不亲和基因Gal-S的一对近等基因系W22(GG)与w22(gg)为材料,组配自交(GG×GG)、正交(gg×GG)与反交(GG×gg) 3个组合。首先采用荧光显微技术, 观察比较了3个组合中花粉管在花丝中的生长过程;其次采用IEF/SDS-PAGE双向凝胶电泳与基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)技术,比较研究了授粉后10 h自交与反交母本W22(GG)花丝蛋白质组的特异表达差异。结果表明,授粉后10 h,自交与正交花粉管伸长可达花丝基部,而反交花丝基部未观察到花粉管;自交与反交母本W22(GG)花丝蛋白质组共检测到25个差异蛋白质点,其中15个在自交中特异表达,10个在反交中特异表达;通过MALDI-TOF-MS质谱测序和MASCOT序列分析,注释了12个蛋白质点;其中自交中特异表达的蛋白质点11、12、14和异交中特异表达的蛋白质点18、22、24可能与玉米异交不亲和密切相关。     

植物核糖核酸酶与转基因工程雄性不育系研究进展

核糖核酸酶(Ribonuclease,RNase)的全名为聚核苷-#-寡核苷酸转移酶,它在植物体内分布广泛,是降解RNA的一类酶的总称。它与植物的衰老、抗逆、自交不亲和、植物雄性不育有密切关系。另一方面,当将从烟草、水稻中分离出的TA29和OsgB6等花药绒毡层及花粉特异启动子与核糖核酸酶基因(barnase)构建成嵌合基因,转移给正常油菜、烟草、番茄、小麦、水稻等植株时,又会产生雄性不育。因此,植物核糖核酸酶的研究日益受到人们的广泛关注。     

培育刺玫月季新品种的初步研究(Ⅰ)——月季远缘杂交不亲和性与不育性的探讨

运用远缘杂交的方法,培养以离抗性为特点的刺玫月季品种群,是我们的目标和愿望。连续3年用现代月季品种与中国原产的蔷薇属植物杂交,共采用121个杂交组合,授粉1645朵花,获得913粒杂种种子,成苗54株,有可能成为建立刺玫月季品种群的第一批品种基础。在了解亲本授粉结实习性基础上,采用不同的授粉方法进行试验,同时观察了花粉在柱头上萌发、生长等情况,发现影响结实率的主要因子是亲本个体的差异,杂交组合的亲和力也很重要。还研究了杂种种子败育与成苗情况,讨论了提高结实率和加速育种进程的途径。     

植物离体嫁接的方法和研究进展(综述)

介绍了离体嫁接的特点和方法并且概括了其组织学和细胞学发育、同化物输导以及生化研究等方面的进展.