同源四倍体水稻与非洲栽培稻杂交的效果

以4份同源四倍体水稻(Oryza sativa,2n=4x=48)和4份二倍体水稻(Oryza sativa,2n=2x=24)为母本,以4份非洲栽培稻(Oryza glaberrima,2n=2x=24)为父本进行远缘杂交配组,共配制32个杂交组合。研究结果表明,非洲栽培稻分别与亚洲栽培稻中的两种倍性水平的水稻品系进行杂交均表现出一定的可交配性,生殖隔离并不很严格。然而,不同倍性的亚洲栽培稻与非洲栽培稻杂交,其结实率表现出明显的差异。二倍体水稻与非洲栽培稻不容易杂交,其结实率比较低(0．32％—1．93％),而同源四倍体水稻与非洲栽培稻较容易杂交,其结实率比较高(1．22％—8．86％,)。由此认为,利用同源四倍体水稻为母本与非洲栽培稻杂交更容易将后者的遗传物质引入亚洲栽培稻。     

Pre-zygotic breeding barriers between the wild diploid potato species Solanum maglia and S. kurtzianum from Argentina

Solanum maglia Schldl. is a wild tuber-bearing species from the Quebrada de Alvarado (Mendoza, Argentina) and the Valparaíso area (Chile). Only diploid cytotypes are known from Argentina, while diploids and triploids are found in Chile. Five diploid accessions from Argentina did not produce seeds upon intercrossing. Thus, the basis of this behaviour and the crossability relations of this species with S. kurtzianum, Bitt. et Wittm., another diploid species that grows in its vicinity were investigated. After checking pollen viability, intraspecific and interspecific pollinations were carried out following an incomplete diallel mating design. Five emasculated flowers were pollinated per each one of 135 different combinations of genotypes (crosses); three flowers were fixed in FAA and analyzed under fluorescent microscopy, whereas the remaining two were left on the plant for fruit and seed set. Pollen tube growth was arrested in the first third of the style and no seeds were obtained in intraspecific S. maglia crosses. In interspecific crosses and according to their direction, pollen tubes either grew normally to the base of the style or were arrested in the last third, producing no fruits or fruits with a variable number of seeds in each. It is concluded that the five S. maglia accesions are, possibly, one clone and, thus, the gametophytic auto-incompatibility system prevents seed formation upon intercrossing. On the other hand, the incompatibility reaction observed in the interspecific crosses might be controlled by one or more genes independent of the S-locus.     

普通大麦(2x)×球茎大麦(2x)的可交配性研究

普通大麦(Hordeum vulgare L.2n=2x=14)品种与球茎大麦(H.bulbosum L.2n=2x=14)的杂交结实率受双亲基因型影响.供试1个大麦品种与球茎大麦的杂交结实率变异在40.4～100.0％之间,9个品种间F_1与球茎大麦的杂交结实率变异在55.5～94.5％之间.供试球茎大麦品系中,Hb05/1和Hb03/7与普通大麦的结实率最高,达95.5％以上,Hb06/9的结实率最低,只有54.8％.环境条件对结实率的影响也很大,气温20～27℃时杂交,结实率较高,但不同品种有不同反应;营养不良能导致幼胚发育中途停止,40ppm 2,4-D 75ppm GA_3混合激素处理比GA_3单一处理明显提高结实率.因此,筛选优良的球茎大麦基因型,创造和选择适宜的环境条件,授粉后喷施混合激素能使杂交结实率大为提高.     

Crossability between cultivated and wild tuber-and non-tuber-bearing Solanums

The cultivated potato has over 200 extant wild relatives many of which contain genes valuable for disease resistance, hardiness, processing and agronomic traits. Crossability of these wild species directly with the cultivated potato is complicated by several reproductive phenomena such as stylar and ploidy barriers and Endosperm Balance Numbers (EBN). However, a systematic analysis of crossability with many of these wild relatives has never fully been examined. Reciprocal crosses were made between cultivated potato and over 400 wild potato accessions; stylar barriers and 2n gamete production were examined as was the fertility of many of the putative hybrids. Generally, the seed/fruit ratio increased the more closely related the species were to the cultivated potato. However, a few crosses were successful in spite of predicted failure due to ploidy or EBN differences. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity within cultivated teas based on nucleotide sequence comparison of ribosomal RNA maturase in chloroplast DNA

The wild tuber-bearing Solanumspecies represent a genetic pool of enormous diversity, embracing high variability for many agronomic traits. S. kurtzianum (ktz), S. chacoense(chc) and S. ruiz-lealii (rzl) are wild diploid self-incompatible relatives of the common potato, Solanum tuberosumssp. tuberosum, with resistance to adverse biotic and abiotic factors. Pollen-pistil/style compatibility relations and seed set in intra- and interspecific crosses among ktz, chc and rzl were investigated. Pre- and post-zygotic hybridization barriers were detected in the three species, with variable incidence because the percentage of genotypic combinations that produced seeds was15–30% and 7–28% in intra and interspecific crosses, respectively. In pollen-pistil/style incompatible combinations, either pollen grains did not germinate or pollen tube growth was arrested at different sites of the style, but mainly in its upper third. Unilateral incompatibility was detected in both intra-and interspecific crosses, as well as bilateral incompatibility in certain combinations. The incompatibility relations observed could be explained by a genetic model with dominant genes in pistils that interact with corresponding dominant genes in pollen, that are independent of the S-locus. The complex arrangement of compatibility relationships found could not be directly related to taxonomic hypothesis or geographic distribution. These results suggest that divergence between the three species has occurred recently, and that internal barriers of reproductive isolation have not been an important factor in their evolution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Doubled haploid production in winter wheat and triticale genotypes,using the Hordeum bulbosum system

Summary An attempt was made to produce doubled haploids on 16 winter wheat and six spring and winter triticale genotypes thought to carry genes for interspecific incompatibility. The potential for haploid production was maximized by the use of Hordeum bulbosum genotypes selected for high crossability on crossable wheat genotypes, the use of two post-pollination applications of gibberellic acid and by the pollination of immature florets.A low frequency of seed was set on both the wheat and the triticale genotypes, having mean seed sets of 0.20 per cent and 0.27 per cent respectively. Although the frequency of embryos (seed quality) was high, doubled haploid production was further limited by poor embryo differentiation and regeneration. Haploid plantlets were obtained from the wheat cultivars Moulin and Renard, although successful chromosome doubling and doubled haploid production was achieved in Moulin only.     

Identification of the lentil's wild genetic stock

The origin of lentil from the taxon Lens culinaris subsp. orientalis has been proved by morphological evidence and breeding experiments. This wild form exhibits variation in many characters and is distributed over a vast area from the Middle-East to central Asia. Characters that are polymorphic in the wild progenitor but monomorphic in the cultigen can be utilized for better identification of the genetic stock which gave rise to the domesticated lentil. Three characters of that kind have been identified in lentil: chromosomal architecture, crossability potential and restriction pattern of chloroplast DNA. Nearly all accessions of the cultivated lentil tested to these three characters have been found monomorphic, but considerable polymorphism exists in the wild accessions. Three subsp. orientalis accessions have been shown to share the above characters with the cultigen and hence can be regarded as members of the genetic stock from which lentil was domesticated. These three accessions originated from eastern Turkey and northern Syria.     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 2. The effect of the timing of pollination

Summary The effect of manipulating the timing of pollination on the fertilization frequency in wheat × tetraploid Hordeum bulbosum hybridizations was investigated as a possible means of overcoming varietal incompatibility in this cross. Pre- and post-anthesis pollinations were made on previously identified highly crossable and poorly crossable wheat genotypes and the stage of development of the individual florets at pollination was expressed in days from anthesis units.In both crossable and non-crossable wheat genotypes, a significant negative linear relationship was observed between floret age and fertilization frequency. The magnitude of the response of early pollination was dependent on the number of alleles for non-crossability present at the Kr loci. The non-crossable cultivar Highbury, possessing more than one allele for incompatibility, showed a slight response. The greatest response was shown by the highly crossable cultivar Chinese Spring, possessing alleles for crossability at all Kr loci. The single chromosome substitution line, Chinese Spring (Hope 5B), possessing the most potent allele for non-crossability, Kr ₁, showed an intermediate response. The H. bulbosum genotype had no effect on the magnitude of this response, influencing only the mean fertilization frequency.     

几个油茶良种可配性研究

为了探讨油茶良种造林配置模式,进一步提高油茶单位面积经济效益,笔者开展良种间可配性研究。试验结果表明：9个杂交组合以长林40号×鄂油102号和长林53号×鄂油102号两组合坐果率最高,分别为62.5%和58.1%,是较好的良种造林配置组合,但搭配比例与方式有待进一步研究。     

Variation of the crossability of durum wheat with maize

With the aim of examining crossability of durum wheat with maize, two sets of durum wheat genotypes and a set of D-genome chromosome substitution lines of the durum wheat variety ‘Langdon’ were crossed with maize, and followed by 2,4-dichlorophenoxyacetic acid (2,4-D) treatment in detached-tiller culture. In crosses of 25 durum wheat genotypes (breeding lines) with maize, percent frequencies of embryo formation increased from 1.4% to 2.8% by adding silver nitrate to the detached-tiller culture solution. In crosses of 32 durum wheat genotypes (advanced lines and varieties) with maize using the silver nitrate addition, frequencies of embryo formation ranged from 0.0% to 15.8%; seven genotypes showing more than 6.0% embryo formation frequency were related in their pedigrees. In crosses of a set of chromosome substitution lines with maize, higher frequencies of embryo formation were obtained in substitution lines with chromosomes 1D, 3D, 4D and 7D. These results suggest that 1) adding silver nitrate to the 2,4-D treatment increases overall frequency of embryo formation but is not effective enough to induce the development of seeds and embryos from all durum wheat genotypes, and 2) some D-genome chromosomes substituted in a durum wheat genetic background may enhance crossability with maize in combination with homoeologous chromosomes of durum wheat. This revised version was published online in August 2006 with corrections to the Cover Date.