RFLP标记水稻遗传距离及其与杂种优势的关系

Genetic Distance Detected with RFLP 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 32个F1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RFLP分析基因组DNA的多态性 ,由RFLP数据计算的Nei’s遗传距离创建聚类树状图 ,探索利用RFLP标记水稻亲本遗传距离预测杂种优势的可能性。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。F1杂种 8个性状的杂种优势显示 ,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 %。播始历期、株高、穗长、有效穗等 4个性状的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。播始历期、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。有效穗和每穗总粒数的中亲优势与遗传距离之间达极显著相关 ,而竞争优势与遗传距离之间的相关系数也较大 ,分别达到 0 .33和 0 .2 3。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 ,可以利用光壳稻、爪哇稻选育不同生态群方向的恢复系和不育系 。

Twelve parents were crossed according to NCⅡ design and thirty two F 1 hybrids were obtained, Shanyou 63 was used as the control. The heterosis of eight characters, i.e. days to heading (DH), plant height (PH), panicle length (PL) and yield components were statistically estimated. The genetic distance (GD) between two parents was evaluated from RFLP 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 separate subgroups, too.The heterosis of number of grains per panicle (GP) was the strongest with a mean of 33.5% in relative heterosis (RH) or mid parent heterosis and a mean of 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. DH, PH, PL and number of effective tillers per plant (ETP). However, GP showed J×J<J×J'<J×I in RH and J×J<J×I<J×J' in SH. The GD between the two parents were significantly correlated with respective RH and SH in three characters, i.e. DH, PH, PL, and with RH in two characters, ETP and GP. The results from the dendrogram were found that the economic heterosis between temperate japonica cultivars was low, the heterosis between subgroups was stronger. Making use of Nuda and javanica rice to develop different ecotypic parents, hybrid rice combinations with very strong heterosis could be developed.