Mottled coloration of haploid-diploid and diploid-triploid mosaic amago salmon Oncorhynchus masou ishikawae

ABSTRACT:   Mottled amago salmon Oncorhynchus masou ishikawe with both yellow- and dark-pigmented skin occurred together with typical albino individuals in a commercial farm. Out of 12 mottled fish examined by DNA content flow-cytometry and erythrocytic nucleus size, three were diploid, eight were haploid-diploid mosaic and one was diploid-triploid mosaic. This fact indicates that the mottled coloration might link to polyploid mosaicism. Genotype of diploid and non-diploid cells at the albino locus was estimated in nine mature mottled fish by observing the frequency of wild-type and albino progeny when mating to homozygous albino ( aa ). One diploid and three haploid-diploid mosaic mottled fish were presumed to have mosaic genotype with both hemizygous ' a ' and heterozygous ' Aa ' cells ( a/Aa ), because the segregation ratio between two phenotypes was 1 : 1. Three other haploid-diploid mosaic fish were presumed to have mosaic genotype with both hemizygous ' a ' and homozygous ' AA ' cells ( a/AA ), because of exclusive occurrence of wild-type phenotype in the progeny. The diploid-triploid mosaic mottled fish was presumed to have mosaic genotypes ' aa / AAA ', ' aa/AAa ' or ' aa / Aaa ', because this fish yielded only albino progeny. One diploid mottled fish produced both two phenotypes but albino embryos appeared with much more frequency than the expectation, when assuming the genotype ' Aa '. Thus, this fish was considered to have mosaic genotype ' Aa/aa '.     

玉米单倍体加倍方法研究进展

主要综述了近年来玉米单倍体加倍方法的最新研究进展。自然加倍法和以秋水仙素及除草剂为加倍剂的化学加倍法是人们研究较多的加倍方法。     

甘蓝型油菜DH群体抗倒伏相关性状遗传分析

为明确油菜抗倒伏性的遗传规律,本文利用抗倒伏性差异显著的2个甘蓝型油菜品系配制杂交组合,构建含280个株系的DH群体,采用作物茎秆强度抗倒测量仪等考种工具对该群体进行连续两年的抗倒伏性鉴定,并利用植物数量性状的主基因 + 多基因混合遗传模型及偏度和峰度分析对抗倒伏性进行遗传分析。结果表明,茎秆抗折力和茎秆抗折强度都受到0对主基因 + 9对微效多基因控制,茎秆抗折力和单株生物量的基因间无互作,茎秆抗折强度的基因间有互补作用,茎秆抗折力和茎秆抗折强度两年的平均遗传率在50%左右,而茎秆直径两年的平均遗传率为69.338 %,单株生物量两年的遗传率分别为52.198%和69.284%,遗传率都较低,性状受环境影响都较大,因此对于茎秆抗折力、茎秆抗折强度、茎秆直径和单株生物量,在育种选择的早期阶段都不宜太严格。同时茎秆抗折强度相比茎秆抗折力更能说明作物的抗倒伏能力,因而在抗倒伏选择育种时应更加关注。     

Potential use of doubled haploid lines for the screening of resistance to yellow rust (Puccinia striiformis) in hexaploid wheat

Doubled haploid lines derived from anther culture of two Iranian spring wheat genotypes‘Ghods’susceptible and‘9106’resistant to yellow rust in Iranian field conditions, and their F₁ hybrids were used in this study. Seedlings of 36 doubled haploid lines, selected out of 96 according to their agronomic traits and the two parental genotypes were inoculated with eight races of yellow rust. The parental genotypes (‘Ghods’and‘9106’) were segregating for some of the races but their doubled haploid lines were either resistant or susceptible to them.‘Ghods’was susceptible to three of the races studied but three doubled haploid lines derived from it were resistant to them. Five selected doubled haploids from the‘9106’genotype and six from F₁ hybrid plants were resistant to all eight races tested. After further investigations in Iranian field conditions it was found that some of these lines can be used as donor genotypes for resistance to yellow rust in wheat breeding programmes. Use of these genotypes should be possible if the French yellow rust races used for selection also represent the dominant races in Iran. It can be concluded that anther culture provides an efficient method for fixing genes of resistance to yellow rust and desirable doubled haploids from F₁ plants can be derived.     

基于最小平方误差的单倍体和二倍体分类方法研究

基于玉米油分的花粉直感效应,采用核磁共振鉴别单倍体,快速、准确、低成本地确定单倍体与二倍体之间的含油率阈值,是实现大批量自动鉴别的前提和关键。提出一种基于最小平方误差的单倍体和二倍体分类方法,通过少量籽粒确定含油率阈值的研究,对单倍体和二倍体进行识别。以10个玉米组合为研究对象,利用核磁共振分析仪测定各组合一定数量单倍体和二倍体籽粒的含油率,依据最小平方误差方法确定各组合油分阈值,并通过逐级递增训练集样本数量的方法,确定油分阈值所需训练集规模,获得含油率阈值,能够满足单倍体正确识别率及对二倍体正确拒识率的均值达到90%以上的要求,为核磁共振全自动单倍体鉴别系统的后期大规模分类提供参数指导,提高分选效率。同时因单倍体生产效率低,运用最小平方误差的方法,通过少量的单倍体及二倍体籽粒来构建油分鉴别单倍体模型,以较小的投入获得更优的分类效果在玉米单倍体自动化分选中具有非常重要的现实意义,将该分类方法应用到全自动核磁分选单倍体系统中,可以达到较好的效果,为加快单倍体工程化育种提供保障。     

The effect of spikelet position on the success frequencies of wheat haploid production using the maize cross system

Barbela is an old Portuguese landrace of wheat that is highly genetically heterogeneous. Different Barbela populations when subjected to aluminium stress show variable levels of tolerance. In order to study the inheritance of this character, doubled haploid (DH) lines were developed. These DH were obtained by intergeneric crosses of 14 different lines of Barbela with maize. During this process the efficiency of the technique was evaluated and suggestions for its improvement were obtained. Several parameters were studied in the crosses: % of crossability, % of embryos per florets pollinated and % of embryos per seed set. The different genotypes of Barbela showed significant variation for the parameters analysed. When the reciprocal crosses were analysed, no differences were found, indicating that cytoplasm differences do not influence the parameters of DH production. However, different spikelet positions (lower, middle and upper) gave highly significant differences in all parameters analysed. Highest success frequencies were obtained for pollinated spikelets in the middle of the spike. This can indicate that concentrating on the middle part of the spike can increase the frequency of DHs obtained using inter generic crosses of wheat with maize. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enhanced anther culture efficiency of indica rice (Oryza sativa L.) through modification of the culture media

The production of microspore-derived green plants from anther culture of indica rice is generally very low compared with japonica cultivars. A modified anther culture medium, consisting of a higher KNO₃ content (31 mm ) and casein hydrolysate (CH, 500 mg/1) but without ammonium salts, was tested in comparison with a medium consisting of the widely-used N6 medium nitrogen background, using four indica × indica F₁ hybrids as test materials. Green plant regeneration frequency was at least three-fold higher in the microspore-calli derived from the former medium than in those derived from the modified N6 medium. More than 700 microspore-derived plants were raised in the field. Another study was carried out using indica × japonica and indica × javanica F₁ hybrids. The results indicated that a medium with higher (3.5 mm ) ammonium sulphate may induce a higher frequency of anthers with microspore-calli but not necessarily lead to a larger number of green-plant regenerating calli. Subsequently, using the indica cv. ‘IR-43’ as the test material, use of a lower level (1.75 mm ) of (NH₄)₂SO₄, in addition to KNO₃ (31 mm ), was found to be better than CH (500 mg/l) for anther-response as well as green plant regenerability of the derived microspore-calli. Nitrate-nitrogen or ammonium-nitrogen alone elicited poor response. Twenty-five media involving combinations of KNO₃ (20–34 mm ) and (NH₄)₂SO₄ (1–3 mm ) were tested for their effects on anther response. Combinations involving KNO₃ (31–34 mM) and (NH₄)₂SO₄ (2.0–2.5 mm ) were found superior not only for achieving greater anther response but also, for subsequent green-plant regeneration. This contrasts with the 28 mm of KNO₃ and 3.5 mm of (NH₄)₂SO₄ in the widely-used N6 medium developed for japonica rice. Other than potassium nitrate and ammonium sulphate, and potassium phosphate to some extent, the levels of other inorganic salts tested did not make any significant difference to the process of anther response. Based on these results, modified media with three levels of ammonium sulphate were tested for anther culture efficiency of indica × japonica and indica × javanica derivatives (F₃s). Microspore-calli derived from a medium of a lower (1.75 mm ) level of (NH₄)₂SO₄ showed a higher regeneration potential overall than those derived from a higher (3.5 mm ) level. A revised medium has been suggested, on the basis of these results, for the realization of improved anther culture efficiency and, consequently, improved feasibility of using doubled haploids in genetic and breeding research with indica rice.     

辣椒单倍体与双单倍体植株叶片光合作用研究

对辣椒单倍体和双单倍体植株的光合作用进行了研究。结果表明 ,在不同光照条件下 ,单倍体植株净光合速率均明显比双单倍体低。在弱光照下 ,气孔的限制作用是单倍体植株净光合速率较低的主要原因 ;而在正常光照下 ,非气孔限制因素是净光合速率降低的主要原因。单倍体植株在强光下受到明显的光抑制 ,单倍体植株净光合速率、气孔导度和表观量子效率均较低 ,在正常光照条件下羧化效率较低 ;光补偿点和细胞间隙CO2 补偿点较高等均是单倍体植株的重要特征     

Somatic embryogenesis from floral tissue of cassava (Manihot esculenta Crantz)

The aim of this study was to examine the embryogenic potential of floral material of the cassava cultivar MCOL 1505. Macerated immature inflorescences were found to be highly embryogenic, with almost 78% of the explants producing somatic embryos. Somatic embryos were also produced from whole male florets and half florets although at much lower rates. No regeneration was obtained from anther, microspore or floret wall tissue. Somatic embryos derived from immature inflorescences were regenerated via organogenesis and the plants derived from this process were assessed in terms of phenotype and ploidy level. If haploid plants could be produced by this method, this would have significant implications in assisting traditional cassava breeding, as this would allow homozygosity to be reached more rapidly. In a crop such as cassava, which is highly heterozygous in nature, the use of haploids in a breeding programme could considerably shorten the time taken to produce new desirable cultivars. This is the first report on plant regeneration through somatic embryogenesis from floral tissue of cassava. This revised version was published online in July 2006 with corrections to the Cover Date.     

Plant Regeneration Through Anther Culture of Three Wild Species of Hordeum (H. murinum, H. marinum and H. bulbosum)

Plant regeneration was achieved through anther culture of three wild species of Hordeum (H. murinum, H. marinum and H, bulbosum). Calli or embryoids were formed from microspores in anthers cultured on a medium containing 6-benzylammopurine (BAP) and ficoll. These calli or embryoids regenerated green or albino shoots and roots after transfer to regeneration media. Green plantlets which developed on regeneration media were transferred to soil where they showed further growth.