Inheritance and agronomic performance of an apetalous flower mutant in Brassica napus L

A spontaneous mutant with apetalous flowers was obtained from a hybrid progeny in Brassica napus. The result of genetic analysis showed that the apetalous character was controlled by only one gene locus, petalous flower exhibited incomplete dominance over apetalous flower and that its expression was not affected by cytoplasmic factors. Sixteen agronomically important characteristics of the apetalous line Apet33-10 were compared with those of its petalled near-isogenic line Pet33-10. Results from 4 years of tests indicated that there was no difference between Apet33-10 and Pet33-10 in all tested agronomic characteristics, except for the pod number of main inflorescence and second-order branches at low sclerotinia disease incidence. The Sclerotinia sclerotiorum disease severity index of Apet33-10 was significantly lower than that of Pet33-10, and correspondingly, the plot yield of Apet33-10 was increased obviously in comparison to that of Pet33-10 if sclerotinia disease was serious. The pod number of main inflorescence of Apet33-10 was significantly lower than that of Pet33-10. On the other hand, the pod number of second-order branches of Apet33-10 was significantly higher than that of Pet33-10, hence no overage difference of the pod number per plant was observed between the two lines.     

Orientation and integration of the classical and molecular genetic maps of chromosome 11 in rice

Summary The classical genetic map and molecular map of rice chromosome 11 were oriented to facilitate the use of these maps for genetic studies and rice improvement. Three morphological markers (d-27, z-2, and la) were crossed to a rice breeding line, IRBB21, which has the Xa-21 gene for bacterial blight resistance. Three F₂ populations were analyzed with RFLP markers known to be located on chromosome 11. Segregation analysis of molecular markers and morphological markers was used to construct an RFLP map for each population. The recombination frequency between markers varied from population to population although the marker order on the maps was the same for all three populations. Based on a common set of markers mapped in the three populations, an integrated map was generated consisting of both RFLP and morphological markers. The genetic distance between markers on this map was determined by taking a weighted average of the data from the three populations. The oriented map serves as a bridge to understand the relationship between the classical and molecular linkage maps. Based on this information, the location of several genes on the classical map can be approximated with respect to RFLP markers without having to map them directly.     

A partially male-sterile mutant line of soybeans,Glycine max (L.) Merr.: inheritance

Summary A partial male sterility system in the soybean (Glycine max (L.) Merr.) germplasm population AP6(SI)CI was found to be controlled monogenically by a recessive allele, msp. Observations of msp msp plants in different environments suggested that environmental conditions significantly affect expressivity of the msp allele with respect to male sterility. We obtained no experimental evidence of cytoplasmic effects on msp expression. Background genotypes, however, seem to affect msp expressivity through their determination of flowering dates and resultant interactions with varying environmental conditions.Homogeneous populations of partially male-sterile plants can be generated by increasing families of msp msp plants in fertility-inducing environments, if measures are implemented to prevent the introduction and/or build-up of fertile genotypes that arise from natural cross-pollinations.Joint contribution: North Central Region, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, and Journal Paper No. J-9596 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011; Project 2107.     

玉米胚乳突变基因与互作对籽粒成份的影响 Ⅲ.su_1基因与sh_2、bt_2基因的互作效应及其利用价值

研究了su_1基因与sh_2,bt_2基因互作对玉米籽粒粒重及营养成份的影响,探讨了这些互作效应对玉米品质育种的利用价值。结果表明:su_1基因与sh_2,bt_2基因互作大幅度降低籽粒百粒重,增加可溶性糖、还原糖和蔗糖含量,降低淀粉含量,增加蛋白质及蛋白质组分中清蛋白、球蛋白和谷蛋白含量,降低醇溶蛋白含量。籽粒氨基酸组成中,天门冬氨酸、谷氨酸、丙氨酸、亮氨酸、赖氨酸、精氨酸等氨基酸受基因互作影响较大。籽粒发育过程中双突变体一般表现为:粒重早期与正常型及单突变体相差不多,但后期增长缓慢;淀粉、醇溶蛋白早期含量较低,后期增长幅度亦较小;蛋白质含量下降量较小;可溶性糖及还原糖早期含量较高,后期下降速度随时期或基因组合而异。研究表明,su_1基因与sh_2、bt_2基因互作可以进一步提高籽粒营养成份,对玉米品质改良具有特殊的利用价值,但提高粒重是这类基因互作效应应用的关键。     

Inheritance of Induced Morphological Mutants in Triticutn monococcum L.

The mode of inheritance of fifteen induced morphological mutants in diploid wheat Triticum monococcum L. was determined. The results showed that earliness, reduced height, uniculm, liguleless branched spike, compact ear, and free-threshing habit of each of these mutants is the result of a single recessive mutation. Red awns and xantha traits are controlled by two recessive genes with duplicate and inhibitory gene interactions, respectively. Some of the early and dwarf mutants were non-allelic. One dwarf GA₃-insensitive mutant with recessive gene action may be a new source. Mutants such as early maturing, dwarf and free threshing habit may be of significance in breeding diploid wheat.     

Inheritance and potentials of a mutated dwarfing gene ndf1 in Brassica napus

A dwarf mutant ‘NDF‐1′, approximately 70 cm high, was derived from a 200‐cm high doubled haploid (DH) line ‘3529’ (Brassica napus), seeds of which were jointly treated with chemical inducers and bombardment of fast neutron. The leaves of the ‘NDF‐1’ mutant were wrinkled and thicker compared with the wild‐type control. The mutant had much lower values than its original parents for all agronomic traits, except for its seed weight. A genetic analysis revealed that dwarfism is under the control of a major gene (designated as ndf1) with a mainly additive effect and non‐significant dominance effect. Because of the high level of resistance to lodging, breeding programmes for double low dwarf oilseed rape and heterosis utilization were initiated. Some new dwarf strains with improved agronomic performance were developed. The hybrid of the cross between the tall parent and the dwarf line showed increased harvest index and significantly higher seed yield than the tall parent or the control variety ‘Zhongyou 821’ and presented an estimated heterosis vigour rate as high as 12.5–25.8%. The dwarf trait will be a promising marker for a simple, economic and efficient way to control the purity of F₁ hybrid varieties in hybrid production of B. napus.     

A new gene for resistance in rice to Asian rice gall midge (Orseolia oryzae Wood Mason) biotype 1 population at Raipur, India

The Asian rice gall midge, Orseolia oryzae Wood Mason (Diptera: Cecidomyiidae), is a major pest of rice in several South and South East Asian countries. The maggots feed internally on the growing tips of the tillers and transform them into tubular galls, onion leaf-like structures called ‘silver shoots’ resulting into severe yield loss to the rice crop. We studied the mode of inheritance and allelic relationships of the resistance genes involved in resistant donor Line 9, a sib of a susceptible cultivar ‘Madhuri’. The segregation behaviour of F₁, F₂ and F₃ populations of the cross between Line 9 and susceptible cultivar MW10 confirmed the presence of a single dominant gene for resistance. Tests of allelism with all the known genes giving resistance to this population indicated that Line 9 possessed a new gene which was designated Gm 9 This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic analysis of presence and absence of lint and fuzz in cotton

Cotton fibre mutants that were fuzzless and/or lintless were crossed with each other and a normal genotype (fuzzy, linted) to produce F₂ and BC₁ generations. F₂ segregation ratios from the cross of fuzzless‐lintless × fuzzy‐linted, for fuzzy‐linted, fuzzless‐linted and fuzzless‐lintless were 45 : 15 : 4. From the cross of fuzzless‐lintless × fuzzy‐linted, the F₂ segregation ratios were 9 : 39 : 16 whereas the BC₁F₁ segregation ratios from the F₁ backcrossed to fuzzless‐lintless were 1 : 3 : 4. These data suggest that the presence or absence of lint and fuzz are controlled by the interaction of four gene loci on non‐homologous chromosomes. We designate these loci as N₁, N₂, Li₃ and Li₄, where N₁ N₁ confers the presence of fuzzy, N₂N₂ confers inhibition of fuzzy initiation and development, and duplicate gene pairs, Li₃Li₃ and Li₄Li₄, determine the presence of lint. Homozygosity for li₃li₃ and li₄li₄ might also inhibit fuzz from development. In other words, they were recessive epistatic to fuzz genes.     

水稻极度分蘖突变体的分离和遗传初步研究

通过EMS诱变处理栽培稻粳灿89(Oryza sative L.indica JX89）种子，从M2代植株中筛选得到一株突变体，其植株形态表现为叶细、色淡、植株矮化和极度分蘖。在将近一年的营养生长过程中，分蘖总数达到2000多个，命名为极度分蘖突变体（Excessive tillering mutant）ext37.ext 37自交所得M3和M4代植株表现同一表型。突变体自交及其与JX89和丰矮占5号（FAZ-5）发杂交F1、F2代结果表明该突变为显性遗传方式，可能涉及两对等位基因。为了观察突变基因对下游基因表达影响的程度，取生长期44天的亲本JX89和突变体ext37的节间分生组织提纯细胞总RNA，进行基因表达谱差异显示分析。结果表明突变体与亲本的基因表达模式有明显的差异，说明可能是处在上游调控基因的突变影响了下游许多基因的表达。目前有关分子生物学的进一步研究正在进行中。     

水稻PCD相关基因的定位研究

植物中的细胞程序化死亡(PCD)在植物的发育、抗病及植物与环境互作等过程中发挥着极其重要的作用.本研究以我国学者发现的特殊的水稻细胞死亡控制突变体3037(M)为材料, 采用微卫星DNA标记 (共计159个微卫星引物) 技术对突变体性状进行基因定位研究.结果表明, 该突变体PCD基因位于水稻的第8染色体和第12染色体,为下一步精细定