Characterization of fertile amphidiploid between <Emphasis Type="Italic">Raphanus sativus</Emphasis> and <Emphasis Type="Italic">Brassica alboglabra</Emphasis> and the crossability with <Emphasis Type="Italic">Brassica</Emphasis> species

A fertile amphidiploid × Brassicoraphanus (RRCC, 2n = 36) between Raphanus sativus cv. HQ-04 (2n = 18, RR) and Brassica alboglabra Bailey (2n = 18, CC) was synthesized and successive selections for seed fertility were made from F₄ to F₁₀. F₁₀ plants exhibited good fertility with 14.9 seeds per siliqua and 32.3 g seeds per plant. Cytological observation revealed that frequent secondary pairing occurred among 3 chromosome pairs in pollen mother cells of plants (F₄) with lower fertility, but not of plants with high fertility (F₁₀). GISH analysis indicated that these F₁₀ plants included the expected 18 chromosomes from R. sativus and B. alboglabra, respectively, but they lost approximately 27.6% R. sativus and 35.6% B. alboglabra AFLP (amplified fragment length polymorphism) bands. The crossability of the Raphanobrassica with R. sativus and 5 Brassica species (13 cultivars) were investigated. Seeds or F₁ seedlings were easy to be produced from crosses × Brassicoraphanus × R. sativus, and B. napus, B. juncea and B. carinata × Brassicoraphanus. Fewer seeds or seedlings were obtained from crosses × Brassicoraphanus × B. napus, B. juncea and B. carinata. However, few seeds were harvested in the reciprocals of × Brassicoraphanus with B. rapa and B. oleracea. The possible cause of fertility improvements and the potential of the present × Brassicoraphanus for breeding were discussed.     

普通小麦与野生大麦的属间杂交

通过活体/离体幼胚培养获得了智利大麦(Hordeum chilense,2n=2x=14)、海大麦(H.marinum,2n=2x=14)及平展大麦(H.depressum,2n=4x=28)与普通小麦(Triticum aestivum,2n=6x=42)之间的属间杂种。智利大麦×小麦及海大麦×小麦杂种在形态上偏向父本小麦,而平展大麦×小麦杂种除穗部性状外,其形态明显偏向母本。所有杂种均自交不孕     

普通小麦与Elymus rectisetus衍生后代的细胞遗传学和形态学研究

披碱草（Elymus rectisctus,以下简写为E．rectiselus)具有二倍性无融合生殖特性,为了获得小麦-E．rectisetus稳定的异附加系或异代换系,对(小麦-E．rectiselus)BC2F2衍生后代的细胞学和形态学进行了研究。结果表明,在BC2F5～BC2F7镜栓的单株中,体细胞染色体数目在22～50条之间,其中42条和44条染色体所占的比例最大,分别占鉴定植株总数的38．0％和35．9％。三个2n=42=21″的稳定株系与普通小麦Fukuhokomugi杂交F1的花粉母细胞染色体构型为2n=18″ 6′,表明有三对E．rectiselus染色体代换到普通小麦中;三个2n=44=22″的稳定株系与Fukuhokomugi杂交F1的花粉母细胞染色体构型为21″ 1′,表明它们为二体异附加系。此外,衍生后代的形态学特征趋向于普通小麦。     

Brassica cytogenetics-a historical journey and my personal reminiscence

This review gives a historical account of Brassica cytogenetics from chromosome number determination to the recent advancements in molecular cytology. Brassica cytogenetics started with the determination of somatic chromosome number of Brassica rapa (syn. B. campestris) by Japanese researcher N. Takamine. Russian botanist G.D. Karpechenko’s synthesis of Raphanobrassica was an important milestone representing the first example of a new species obtained through experimental hybridization. Japanese scientists Morinaga, and Nagaharu U pioneered genome analysis and unraveled the cytogenetic architecture of crop brassicas. The 1930s witnessed karyotype investigations on somatic chromosomes. Later, pachtene chromosome analysis led G. Röbbelen (1960) to propose the genetic constitution of the basic archetype. Brassica chromosomes are very small and lacking distinctive physical landmarks which makes difficult to generate reliable karyotypes. In recent years, classical cytogenetics has given way to molecular cytogenetics. Molecular karyotypes have been constructed using fluorescence in situ hybridization (FISH) with ribosomal DNA probes with individual chromosomes reliably identified. Since early 1950s, syntheses of natural alloploid species and of late, wide hybridizations between wild and crops species have successfully been carried out taking advantage of recent developments in tissue culture techniques. In early 1980s, the amenability of Brassica species for protoplast regeneration and fusion was demonstrated which enabled the syntheses of a large number of somatic hybrids including a substantial number of intertribal combinations. These experiments extensively helped in expanding the genetic base of existing allopolyploid species and increasing use of related wild germplasm for incorporating new genes which had not been accessible till recently. Comparative genomics between Arabidopsis and Brassica species have elucidated evolutionary processes. At present, Brassica and Arabidopsis regarded as model organisms in the field of experimental biology.     

披碱草和野大麦杂种F1与BC1代细胞遗传学研究

对亲本披碱草(Elymus dahuricus)和野大麦(Hordeum brevisubulatum)及其杂种F₁和BC₁代体细胞染色体数和花粉母细胞(PMC)减数分裂染色体行为进行观察和分析。结果表明:亲本披碱草的染色体数为2n=42,野大麦为2n=28;正、反交杂种F₁染色体数均为35;BC₁代染色体发生了数目上的差异,变异范围为28~35,并出现很多非整倍性植株;披碱草的PMCMI二价体配对频率很高,野大麦PMCMI出版少量的四价体、三价体和单价体,但以二价体占优势;正反交杂种F₁减数分裂不规则,单价体的普遍存在是造成杂交不育的重要原因;BC₁代的PMCMI单价体频率较F₁代有所下降,二价体频率有所增高,有些株系的环状二价体占绝对优势,这为杂种育性恢复提供了细胞学依据。