Brassica cytogenetics-a historical journey and my personal reminiscence

本文综述了芸薹属细胞遗传学从染色体数目鉴定到分子细胞生物学的发展历程。芸薹属细胞遗传学研究始于日本科学家N.Takamine对白菜型油菜Brassica rapa(syn.B.campestris)体细胞染色体数目的鉴定。俄国植物学家G.D.Karpechenko首次成功地合成了萝卜甘蓝(Raphanobrassica),这项成果的获得是实验室杂交合成新物种的里程碑。日本科学家Morinaga和Nagaharu U率先开展了基因组研究,揭示了芸薹属作物的细胞遗传学结构。二十世纪三十年代广泛开展了体细胞染色体的核型研究。随后,G.Rbbelen在1960年对粗线期染色体进行研究,提出了原始核型的遗传结构。但由于芸薹属染色体非常小,没有明显的形态标识,因此很难获得可靠的核型,近年来由于分子细胞遗传学的迅速发展,科学家采用以rDNA为探针的荧光原位杂交(FISH)技术成功地构建了分子核型。二十世纪50年代初期以来,由于组织培养技术的发展,人工合成了自然界已有的芸薹属栽培异源多倍体种,并进行了芸薹属作物和野生种之间的远缘杂交研究。1980年后发展起来的原生质体再生和融合技术更加促进了大量体细胞杂种的合成,包括相当数量的族间组合。虽然野生种质的基因尚待发掘,但这些实验大大拓展了异源倍性物种已有的遗传基础,增加了近缘野生种质资源的可利用价值。近年来开展的拟南芥和芸薹属物种之间的比较基因组学研究,不仅阐述了进化过程,也使芸薹和拟南芥成为近年来实验生物学的模式植物,为进一步开展细胞遗传学研究奠定了基础。

This review gives a historical account ofBrassicacytogenetics from chromosome number determination to the recent advancements in molecular cytology.Brassicacytogenetics started with the de-termination of somatic chromosome number of Brassica rapa（syn.B.campestris） by Japanese researcher N.Takamine.Russian botanist G.D.Karpechenko＇s synthesis ofRaphanobrassicawas an important mile-stone representing the first example of a new species obtained through experimental hybridization.Japa-nese scientists Morinaga,and Nagaharu Upioneered genome analysis and unraveled the cytogenetic archi-tecture of crop brassicas. The 1930s witnessed karyotype investigations on somatic chromosomes. Later,pachtene chromosome analysis led G. R bbelen （1960） to propose the genetic constitution of the basic archetype.Brassicachromosomes are very small and lacking distinctive physical land marks which makes difficult to generate reliable karyotypes. In recentyears,classical cytogenetics has given way to molecular cytogenetics. Molecular karyotypes have been constructed using fluorescencein situhybridization （FISH）with ribosomal DNAprobes with individual chromosomes reliably identified. Since early1950s,synthesesof natural alloploid species and of late,wide hybridizations between wild and crops species have success-fully been carried out taking advantage of recent developments in tissue culture techniques.In early 1980s,the amenability ofBrassicaspecies 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 allopoly-ploid species and increasing use of related wild germplasm for incorporating new genes which had not been accessible till recently. Comparative genomics between Arabidopsis and Brassicaspecies have eluci-dated evolutionary processes.At present,Brassica and Arabidopsis regarded as model organisms in thefield of experimental biology.