利用无融合生殖和多倍体化探索水稻育种新途径

The breeding of super rice has been an important trategy to solve the potential crisis of shorten food supply in the world. However, there are still many difficults to realize the aim of increasing 30-50% yield of food only by conventional breeding or hybrid breeding in diploidy. Reviewing on the tendance of crop evolution, we suggested a new pathway of super rice breeding by utilization of double heterosis of wide cross and polyploidization. Using this theory in the project, we had got some outstanding achievements, First, we explained the theorical basis and technique route about the trategy and obtained an Inventor's Patent in China. Second, we established "the method of formation of polyploid rice with high frequency by combination of tissue culture and chemical induction", which raised polyploid inducing rate of 5% up to 46.7%，and applied for an Inventor's Patent in China. More than 200 polyploid rice cultivars and hybrids had been formed, which included cultivar polyploid such as apomictic lines, wide compatible lines, male sterile lines and restore fertility lines and wide hybrid polyploids of intersubspecies indica and japonica, interspecies cultivated and wild rice in AA genome and intergenomes AA and others in BB, CC, BBCC, CCDD, EE and GG. Especially, four polyploid hybrids of ssp. indica and japonica with powerful heterosis had been selected. They showed many characteristics of super rice such as many panicles, big grain high frequence of seed set. Some polyploid hybrid from cross of cultivated and wild rice with powerful heterosis, higher rate of seed set and non-drop seed. The preliminary results from cytogenetic observation had conformed the rate of seed-set of polyploid rice is closely interrelated to parent relationship and chromosomal behavior in meiosis. The progress in the projecd not only lead us to gain other projects from 863 plan and SNFC, but also in fact, had opened a new pathway of rice breeding, and provided good background for establishment of a new subject "Evolution Breeding". Some parts of the results had published in 6 papers, and others will be found in some international magazines.

从作物进化趋势看，水稻是二倍体、基因组小。增加基因组数、提高倍性水平、利用异源多倍体杂种优势是水稻育种新途径。针对同源四倍体水稻结实率低的关键问题，采取拉大亲缘关系距离、应用广亲和基因和无融合生殖材料等措施，构建亚种间、种间和栽野种间多倍体，经综合学科鉴定选择，达到提高结实率，选择优良多倍体和无融合生殖株系的目的。

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