RAPD分子标记水稻遗传距离及其与杂种优势的关系

Genetic Distance Detected with RAPD Markers among Rice Cultivars (Oryza sativa L.) and its Relation to Heterosis

用 12个水稻亲本按NCⅡ设计配组 32F1 杂种 ,以汕优 6 3为对照 ,研究播始历期、株高、穗长及产量因素等 8个性状的杂种优势。并以 12个亲本为DNA样品来源 ,通过随机引物PCR扩增基因组DNA的多态性 ,探索利用RAPD标记水稻亲本遗传距离预测杂种优势的可能性。由RAPD数据计算的Nei’s遗传距离创建聚类树状图。聚类分析结果表明 ,籼稻和粳稻容易被分开 ,普通粳稻又容易与光壳稻、爪哇稻分开 ,但光壳稻和爪哇稻混合聚在一起。F1 每穗总粒数的优势最强 ,中亲优势平均为 33.46 % ,竞争优势平均为 2 3.10 %。F1 播始历期、株高、穗长、有效穗 4个性状中亲优势和竞争优势均表现为粳×粳 <粳×偏粳 <粳×籼。每穗总粒数的中亲优势也表现上述趋势 ,而竞争优势则是粳×粳 <粳×籼 <粳×偏粳。全生育期、株高、穗长的中亲优势和竞争优势与遗传距离之间均达极显著相关。每穗总粒数的中亲优势与遗传距离之间达显著相关 ,而竞争优势则达极显著相关。根据聚类图发现普通粳稻亚群内杂种优势较弱 ,亚群间即生态群间的杂种优势较强 ,群间即籼、粳亚种间杂种优势更强。利用光壳稻、爪哇稻选育不同生态群方向的恢复系和不育系 ,配组超强优势的杂交稻组合。

Twelve parents were crossed according to NCⅡ design and thirty-two F 1s hybrids were obtained,and Shanyou 63 was as control variety. The heterosis of eight characters, i.e. days of heading, plant height, panicle length and yield components were statistically estimated. The genetic distance (GD) between two parents was evaluated from RAPD banding patterns among parents. The possibility was explored that genetic distance was used to calculate heterosis between two parents. Based on the pair-wise comparisons of amplification products the genetic distance was calculated using Nei's genetic distance and a dendrogram was constructed using an unweighted pair group method with arithmetical averages (UPGMA). The indica and japonica cultivars were easily classified by cluster analysis, and temperate and tropical japonica cultivars were classified into different subgroups,too,but Nuda and javanica cultivars were usually clustered in mixed subgroup. The heterosis of number of grains per panicle was the strongest with a mean 33.5% in relative heterosis (RH) and a mean 23.1% in standard heterosis (SH). Heterosis was compared among three cross-combination groups: J×J, J×J', and J×I. In general, RH and SH showed an order of J×J<J×J'<J×I in four characters, i.e. days to heading, plant height, panicle length and number of effective tillers. However number of grains per panicle showed J×J<J×J'<J×I in RH and J×J<J×I<J×J'in SH. The GD between two parents were significantly correlated with respective RH and SH in four characters, i.e. days to heading, plant height, panicle length and number of grains per panicle.The results from the dendrogram were found that the economical heterosis between temperate japonica cultivars was low, the heterosis between subgroups was stronger and the heterosis between groups ( indica/japonica) was strongest. Making use of Nuda and javanica, parents of hybrid rice as distinct from ecotype were bred,and super high yield hybrid rice combinations had been bred.