Utilization of alien genes to enhance Fusarium head blight resistance in wheat – A review

Fusarium head blight (FHB) is a destructive disease of wheat worldwide. Sources of resistance to FHB are limited in wheat. Search for novel sources of effective resistance to this disease has been an urgent need in wheat breeding. Fusarium head blight resistance has been identified in relatives of wheat. Alien chromatin carrying FHB resistance genes has been incorporated into wheat through chromosome addition, substitution, and translocation. Relatives of wheat demonstrate a great potential to enhance resistance of wheat to FHB.     

Potential for Selection in the Progeny of an Interspecific Hybrid in Foxtail Millet

Genetic variation for morphology and grain yield components was studied in the F₂ and 14 F₃ families of an interspecific cross of Setaria italica (foxtail millet) with S. viridis s. s. (green foxtail). It appeared possible to recover the cultivated type using a simple selection procedure in F₂ and F₃. Comparison with a cross involving S. viridis var. major (giant green foxtail) is discussed.     

Congruity backcrossing as a means of creating genetic variability in self pollinated crops: seed morphology of Phaseolus vulgaris L. and P. acutifolius A. Gray hybrids

Summary Seeds of early generations of three reciprocal congruity-backcross (CBC) pedigrees, developed by backcrossing Phaseolus vulgaris-P. acutifolius hybrids to each of the parent species in alternate generations, exhibited a preponderance of traits (size, shape, color, and pattern) of the cytoplasmic parent. The large size of Red Cloud (V₁), the P. vulgaris parent common to all of the pedigrees, dominated pedigrees with V₁ as the cytoplasmic parent, while the small size and rounded or square shapes of the tepary parents, wild P. acutifolius var. acutifolius PI 263590 or G400445 (A₁₉), wild P. acutifolius var. latifolius PI 406622 (A₁₀), or cultivated P. acutifolius var. latifolius Serowi PI 319443 (A₉), were the majority phenotypes when P. acutifolius was the cytoplasmic parent. Continuing through the second cycle of CBC, that is the second backcross with each of the parent species or the fourth backcross, began an amelioration of the apparent cytoplasmic effect on gene expression, as reciprocal pedigrees became more alike, usually with intermediate expression of parental traits or the appearance of new traits. The large seed size of V₁ was recovered in hybrids with P. acutifolius cytoplasm and the kidney shape of V₁ became rare in hybrids with P. vulgaris cytoplasm. Although the tepary-bean parents represented two subspecies and both cultivated and wild P. acutifolius, the three sets of reciprocal-hybrid pedigrees with P. vulgaris Red Cloud are surprisingly similar. It may be that the exotic parent used to develop a CBC pedigree should be selected more for combining ability in the interspecific cross than for specific economic traits. While the number of generations (six or more) required to produce fertile, intermediate CBC hybrids (that did not require embryo rescue) may preclude routine use of this method by practical plant breeders, the crossability of advanced hybrids with both parental species and the amount of variability apparent in advanced-hybrids progenies suggests that CBC would be valuable for maintaining exotic germplasm in immediately useful forms.     

Relationships between African species of the genus Cucumis L. Estimated by the production,vigour and fertility of F1 hybrids

Summary The production, vigour, and fertility of F₁ hybrids between nine African species of the genus Cucumis L. were studied as a measure of the relationships between the species. Hybrid plants were obtained from 29 out of the 72 possible cross combinations. Two F₁ hybrids died as seedlings, and 27 hybrids were raised to maturity. Pollen production and stainability varied greatly amongst these hybrids, as did fruit and seed set following self pollination and backcrossing with either parental species. The fruit shape of the hybrids was always intermediate between that of both parental species.Two species appeared to be closely related: C. prophetarum L. and C. anguria var. longipes A. Meeuse. Most other species produced highly to moderately fertile F₁ hybrids with at least one other species. C. metuliferus Naud. produced only sterile hybrids with C. zeyheri Sond. 2x. The results sustain the recent taxonomic classification of the genus (Jeffrey, 1980).     

The evaluation of superior Hordeum bulbosum L. genotypes for use in a doubled haploid barley breeding programme

Summary Eight Hordeum bulbosum selections were produced from a cross between Cb 2920/4 and Cb 2929/1, two genotypes widely used in doubled haploid breeding programmes. The selections were hybridized with barley to evaluate their ability to produce high proportions of well-differentiated haploid embryos compared with Cb 2929/1 as control. We report here an initial small-scale investigation followed by a larger-scale test in two different environments to assess seed setting, haploid embryo differentiation rates and VB hybrid formation. These VB embryos contain both parental sets of chromosomes and occur more frequently in the glasshouse during the winter. Two of the eight selections were identified as combining the desirable characteristics of both parents, namely high seed setting on cv. Vada which is partially incompatible with H. bulbosum, large numbers of well-differentiated haploid embryos and a low incidence of VB hybrids. The selections are available for release to interested research workers and plant breedersAbbreviations DH doubled haploid - VB a hybrid from H. vulgare x H. bulbosum which contains both parental sets of chromosomes     

高粱与旱稻属间杂交部分遗传物质导入的F_3及BC_1表型鉴定

以高粱(S.BICOLOR)为母本、旱稻(O.SATIVA)为父本进行属间杂交,F1出现双亲没有的短芒和黄色柱头新性状,并能在F2、F3及BC1稳定遗传。F3在株高、穗长、穗型、分蘖性等性状上仍疯狂分离,并出现父本白色籽粒单株。BC1在株高、分蘖二性状上接近父本,回交效应非常明显,T测定无差异,并出现多子房新性状。高梁与旱稻杂交及回交,能创造变异,产生新性状,对创造矮秆、优质、多子房新种质十分有效。然而,二者杂交后代主体性状仍似母本,只表现父本少数性状,属于部分遗传物质导入。     

高产、优质、多抗晚籼杂交稻新组合博优679选育与应用

用适应性强的本地(合浦)野生稻和IR 2061、IR 661等育种材料,通过单交、复交,多世代、多株系的系谱选育,选育成一系列优良株系。用博A等不育系对所选育出的优良株系进行测交,其中第679株系与博A配组最好,定名为博优679。该组合于2003年和2004年参加广西区试和生产试验,增产显著,米质优,抗性好;2005年1月通过广西农作物品种审定委员会审定,并被指定为广西主导品种之一,现正在广西、广东、海南等地大面积推广。     

松材线虫虫体特异表达cDNA文库的构建与分析

松材线虫取食和致病相关基因的鉴定是揭示松材线虫病致病机制的重要研究内容。以松材线虫混合虫体为测试方,线虫卵为驱动方,构建二者差减cDNA文库。文库测序结果经序列拼接、功能注释,共获得松材线虫虫体特异表达的有效EST序列354个,拼接后获得34个重叠群,其中15个重叠群获得明确的功能注释,其中MixC12、MixC25、MixC33分别与过氧化物酶、β-1,4内切葡聚糖酶、锌指家族蛋白有较高的同源性,这些基因被认为与植物线虫的取食和致病性密切相关。RT-PCR分析验证了所获得的差减cDNA的代表性。     

Observations on interspecific compatibility and meiotic chromosome behavior of Capsicum buforum and C. lanceolatum

The wild species, Capsicum buforum Hunz. and C. lanceolatum(Greenm. ex J.D. Sm.) Morton and Standl. were hybridized to nine different Capsicum species to understand their taxonomic and genetic relationships. With C. buforum as the male parent, the compatibility to the nine species varied from species to species and ranged from producing under-developed embryo, seed coat, seedless fruit, to no fruit set. When C. buforum was the female parent, it was incompatible (no fruit set) to the nine Capsicum species tested. When C. lanceolatum was the female parent, the hybridizations to the other species ranged from aborted embryo, seed coat, seedless fruit or no fruit. As a pollen parent, C. lanceolatum was incompatible (no fruit set) to the species investigated. In pollen mother cells (PMCs) of C. buforum, 24 chromosomes (n = 12) paired as 12 bivalents with chromosome lagging at meiotic anaphase-I. Twenty-six chromosomes (n = 13) were detected in PMCs of C. lanceolatum. In C. lanceolatum most chromosomes paired as bivalents, but one quadrivalent was observed in some cells. C. buforum was found to be self-incompatible, while C. lanceolatum was self-compatible.