Study on Persimmon Breeding by Means of Tissue-Cell Culture Systems

利用组织培养体系和细胞培养体系进行柿品种改良，试图通过诱导体细胞无性系变异，通过细胞融合获得体细胞杂种，并通过挽救未成熟胚的方法获得3n植株。主要研究结果如下：(1)对次郎愈伤组织进行了伽马射线照射和PFP处理，获得了再生植株。将再生植株与原始次郎植株进行了形态比较和同工酶分析，但两者之间没有差异。需要更多的诱变剂才能诱导柿的体细胞无性系变异。(2)甜柿愈伤组织原生质体的研究。二郎和Suruga被电融合并培养成植物再生。从127个愈伤组织系中获得了再生植株，其中22个愈伤组织的核DNA含量是亲本愈伤组织的两倍。结果表明，再生植株为两个品种间的体细胞杂种，染色体数目约为2n=180，是亲本植株的两倍。(3)对几个柿品种的花粉粒大小分布进行了研究。所有品种的巨型花粉均明显大于普通花粉，但巨型花粉占总花粉的比例因品种不同而不同，在增吉丸和AmayotSumizo为10%左右，在Okugosho为2%左右，其余品种在1%以下。核DNA分析表明，这些巨型花粉为未还原的2n花粉。用62um尼龙滤网将未还原的巨型花粉分选后用于授粉，用真吉丸和大久正的巨型花粉分别与次郎和扶余杂交。将获得的幼胚进行体外解剖培养，染色体计数结果表明，获得的植株均为非无倍体(2n=9x=135)，其核大小明显大于六倍体亲本。

Using tissue and cell culture systems for persimmon cultivar improvement, we tried to induce somaclonal variation, to develop somatic hybrids by cell fusion and to obtain 3n plants through rescue culture of immature embryos resulting from pollination with unreduced pollen. The results obtained are summarized as follows :(1)gamma ray irradiation and PFP treatment were applied to Jiro callus and plantlets were regenerated from the affected celli. The regenerants were compared with the original Jiro plants morphologically and by isozyme analyzes, however, no differences were observed between them. More mutagens need to be tested to induce somaclonal variation in persimmons.(2) Callus protoplasts of cvs. Jiro and Suruga were fused electrically and cultured for plant regeneration. Regenerants were obtained from 127 callus lines, 22 of which were shown to have twice the nuclear DNA content of the parental calli. RAPD analysis and chromasome counting revealed that the regenerants were somatic hybrids between the two cultivars and had dodecaploid chromosome number of around 2n=180, which is twice the number of parental plants.(3) Pollen size distribution was examined with several persimmon cultivars. Giant pollen, distinctly larger than the normal pollen, were observed in all the cultivars but the ratio of giant pollen to total pollen varied among cultivars, ranging from about 10% for Zenjimaru and Amayotsumizo, about 2% for Okugosho to less than 1% for the rest cultivars. Nuclear DNA analysis revealed that those giant pollen is unreduced 2n pollen. Unreduced giant pollen was sorted by 62mum nylon mesh filter and used for pollination ; giant pollen of Zenjimaru and Okugosho were crossed for Jiro and Fuyu flowers, respectively. The resultant immature embryos were dissected and cultured in vitro.Chromosome counting demonstrated that the plantlets thus obtained were all nonaploid (2n=9x=135) and their nuclear size was clearly larger than that of hexaploid parents.