小麦(Triticum asetivum L.)杂交种下调表达的GTP结合蛋白基因TaRab的克隆与鉴定

杂种优势的形成与杂种一代中亲本基因的表达方式改变有关.为深入研究小麦杂种优势形成的分子机理,利用通过抑制性差减杂交(SSH)方法获得的小麦Rab类GTP结合蛋白基因片段为探针,筛选普通小麦品系3338三叶期叶片cDNA文库,获得了一个小麦Rab家族基因TaRab.同源性比较和序列分析显示,该基因与拟南芥Rab类GTP结合蛋白基因具有90%氨基酸序列相似性.结构分析表明,它具有GTP结合蛋白4个典型结构以及Rab家族成员特有的YYRGA结构域.半定量RT-PCR表达检测结果显示,TaRab基因在叶片的表达水平要高于其他组织器官.研究还发现,该基因在三叶期、分蘖盛期的根系和叶片中为杂种下调表达.采用电子定位方法,将TaRab基因初步定位在7B染色体的着丝粒区域和C-7DS5-0.36两个区域.在此基础上,对Rab蛋白基因差异表达与杂种优势表现的关系进行了讨论.     

皱纹盘鲍杂交群体与自然种群遗传差异的研究

利用RAPD技术对皱纹盘鲍自然种群和杂交养殖群体进行了遗传差异分析,共检测到173个位点．在自然种群和杂交群体之间及两个杂交群体之间都存在差异,并得到一些群体的特异性片段．利用PopGen32软件计算了各个群体的多态位点比例、平均遗传杂合度、Shannon多态性指数和群体问的遗传距离．结果表明,杂交群体的遗传多样性高于自然群体,从遗传多样性角度揭示了皱纹盘鲍杂种优势的存在．     

Cloning and expression profiles of 15 genes encoding WRKY transcription factor in wheat （Triticum aestivem L.）

WRKY proteins are involved in various physiological processes, including biotic and abiotic stress responses, hormone responses and development. However, no systematic identification, expression and function analysis of WRKY genes in wheat were reported. In this study, we isolated 15 wheat cDNAs with complete open reading frame （ORF） encoding putative WRKY proteins using in silico cloning. Phylogenetic analysis indicated that the 15 wheat WRKY genes belonged to three major WRKY groups. Expression analysis revealed that most genes expressed drastically in leaf, except Ta WRKYIO which expressed in crown intensively. Four genes were strongly up-regulated with the senescence of leaves. Eight genes were responsive to low temperature, high temperature, NaCl or PEG treatment. Moreover, differential expression patterns were also observed between wheat hybrid and its parents, and some genes were more responsive to PEG treatment in the hybrid. These results demonstrated that wheat WRKY genes are involved in leaf senescing and abiotic stresses. And the changed expression of these WRKY genes in hybrid might contribute to the heterosis by improving the stress tolerance in hybrids.     

茶树杂交种金观音与黄观音的选育及应用

选配铁观音（♀）与黄金桂（♂）杂交,从F1中分离单株,经20多年的试验研究与生产示范,育成综合性状优异的杂交种金观音（又名茗科1号）、黄观音,先后通过省级与国家级品种审定．两个杂交种适制鸟龙茶与绿茶,制优率高,黄观音亦适制红茶、白茶．花香明显,品质优异,超过黄金桂,香气与制优率均比铁观音高．茶多酚、氨基酸等生化成分和萜烯醇类及其氧化物、酯类、内酯类、酮类等乌龙茶香气特征成分含量丰富,金观音、黄观音的遗传性状分男ll趋向母本与父本．超亲优势强,产量高,比双亲平均增产20％至60％以上,扦插繁殖力、抗性与适应性强,超过双亲．开采期早,与黄金桂同期,分别比铁观音提早13d与10d左右．适宜在福鼎大白茶的适栽区域推广．     

香菇的正反双单杂交育种

选用香菇的杂交菌株农１（Ｎ１）与野生株（Ｑ）孢子单核体及其自交后代进行正反双单杂交,以拮抗试验辅以液体出菇试验进行鉴定,得到６个杂交后代,选用１号与４号菌株进行栽培,它们都长出了正常的子实体,栽培结果表明：１号菌株产量明显高于４号菌株、Ｑ及Ｎ１,其生物转化率为１３４３％,产量优势为２４７４％,其杂种优势十分显著,同时也表明以Ｑ的孢子单核自交后代同Ｎ１正交（ＱＱ×Ｎｍ）育种优越于以Ｎ１的孢子单核体自交后代同Ｑ（ＮＮ×Ｑｍ）的反交育种     

Heterosis and combining ability evaluation for growth traits of blunt snout bream （Megalobrama amblycephala） when crossbreeding three strains

The blunt snout bream(Megalobrama amblycephala)is a major aquaculture species in the Chinese freshwater polyculture system.In this study,complete diallel crossing of three strains(i.e.,Liangzi[LZ],Poyang[PY]and Yuni[YN])was used to evaluate the combining ability and heterosis effect of intraspecific crossbreeding on the growth performance(i.e.,body weight,total length,body length,body height,and Fulton’s coefficient of condition).The offspring produced from the three strains were reared in a communal pond for 20 months,and nine microsatellites were used to assess their pedigree.Of the749 offspring,708(94.53%)could be assigned directly to a single parental pair.Significant differences were observed in body weight(BW)among the different combinations,indicating that the combining ability of BW from each strain was significantly different.The general combining ability(GCA)of BW from the sire was much higher than that from the dam.The GCA for the dam and sire of the LZ and YN were the largest and the smallest,respectively.The special combining ability of YN$9 PY#was the largest,and YN$9 PY#showed significantly positive heterosis effects on all F1growth traits,except for Fulton’s condition coefficient(K)(P\0.05).In addition,significant positive linear correlations were found between the mean BW of corresponding progeny and the H E of the parental generation(y=600.7x-29.472,r=0.8651,P=0.0026),H O(y=1206.9x-518.14,r=0.7436,P=0.0216),and the polymorphism information content(y=1021.3x-331.31,r=0.8245,P=0.0063)as determined by a correlative test.The findings obtained from the study will be important for future considerations of M.amblycephala stock improvement programs.     

关于近交衰退值和杂种优势值的讨论

当性状表现涉及到多个基因座位时，只人有关座位的基因型值以加性方式组合在一起，群体平均值就是各座位贡献的总和。     

杂种优势的一种可能的分子机理——杂合酶的协同效应

根据酶的结构与催化功能关系原理，提出了杂种优势的一种分子机理的假设，即杂合酶的协同效应，显性互补和异质等位基因互补是其中两个特例。应用杂合酶的正负协同效应能够很好地解释杂种优势的正负性和强弱性。杂合酶的特性与杂种优势的许多性质是一致的。杂合酶的活性多态性得到了同工酶的验证，其中的杂合酶活性强度与杂种优势有很强的正相关。从多聚酶的亚基间相互作用所产生的构象变化的传递形成的催化反应的协同性，讨论了杂合