Abstract: 【Objective】 It is of great significance to identify indica or japonica accurately and predict the heterosis by genetic distance for super high-yielding rice breeding and exploring the indica-japonica inter-subspecies heterosis of rice. 【Method】The indica-japonica attribute of twelve Zheyou hybrid rice lines and their parents were identified by 19 pairs of InDel molecular markers designed on the basis of the comparative genomic DNA sequences between indica variety 9311 and japonica variety Nipponbare. According to the gene frequency of indica/japonica genomics detected by InDel molecular markers, a method was set up modified upon Lu’s report, and all the tested materials were judged for their different attributes, i.e indica, indica-cline, intermediate indica cline, intermediate japonica-cline, japonica-cline and japonica six types. Genetic distances among 13 rice parents (one sterile line and 12 restorer lines) were assessed by InDel molecular markers and calculated by using Nei’s way. The genetic similarity (GS) was reckoned by using UPGMA method to analyze the cluster of genetic similarity. Principal component analyses (PCA) were conducted using SPSS 17.0 statistical analysis software to InDel band assignments. Then, on the basis of the average values of the eigenvectors of the first and second principal components, a scatterplot was created. The control heterosis of six traits, grain yield, effective panicles per hole, spikelet number per panicle, seed setting rate, 1000-grain weight and grain weight per panicle in hybrid F1 were investigated. Furthermore, the correlations between InDel genetic distance and heterosis related to yield traits were analyzed, and possible relation to the performance of Zheyou hybrid rice lines were discussed. 【Result】 The indica-japonica attributes of the tested materials were identified and the results showed that the sterile line Zhe 04A is identified into japonica type. Eight restoring lines were thought of belonging to indica or indica-cline type, and eight combinations derived from them were judged into a range from intermediate indica-cline to japonica-cline type, it was also verified that these eight combinations were typical indica-japonica combinations. Another four restoring lines were divided into the type of japonica-cline, the four combinations from these lines were judged into japonica type. The cluster analyses were indicated that thirty-five materials could be divided into two major groups, indica group, and japonica group, at 0.350 score of GS. At 0.638 score of GS, the japonica group was divided into two sub-groups, intermediate japonica-cline and japonica /japonica-cline group. Zhe 04A and four japonica×japonica hybrids and their restoring lines fall into the latter group. Meanwhile, the indica group had eight indica type restoring lines of indica×japonica hybrids, three indica control and indica hybrid rice Shanyou 63. When all the twelve combinations were analyzed as a whole, the correlations between the InDel genetic distance and economic yield, number of grains per panicle, grain weight per panicle were significantly positively, but the InDel genetic distance was significantly negatively correlated to seed-setting rate. However, when the eight indica-japonica hybrids were tested only, the InDel genetic distance was only significantly positively correlated with grain weight per panicle and 1000-grain weight. 【Conclusion】Eight combinations from twelve tested Zheyou series combinations were verified attributing to the typical hybrids of japonica sterile line×indica restoring line. Genetic distance tested by InDel molecular marker had higher ability to predict heterosis among different breeding types of hybrids rice, especially for the heterosis of grain weight per panicle. With the increase of InDel genetic distance, the heterosis of tested combinations would be mainly expressed in enhancement of grain weight per panicle.

Key words: Oryza sativa L. , InDel , molecular marker , heterosis , indica-japonica hybrids