Comparison of Characteristics for Breeding Utilization of Isonuclear Alloplasmic Liuqianxin A with Four Cytoplasm Sources

The BT type of cytoplasmic male sterile (CMS) line plays a predominant role in japonica hybrid rice (Oryza sativa L.). Incomplete sterility of the CMS line is one of the major restraints in heterosis utilization of japonica hybrid rice. This study aimed at comparing a set of isonuclear alloplasmic sterile lines that might be used in japonica hybrid rice breeding. Four Liuqianxin-based isonuclear CMS lines in WA, HL, BT, and CL cytoplasmic backgrounds were crossed with Liuqianxin B line for evaluating the male sterile stability, flowering habits, outcrossing rate, and restorable ability. The sterility was characterized as stained abortion in most pollen granules of the BT-, HL-, and CL-type Liuqianxin A and typical abortion in most pollen granules of WA-type Liuqianxin A. The selfing rate of the BT-type Liuqianxin A was 0.60%, which might cause a risk in producing seed of hybrid rice. However, no selfing spikelets were obtained in the HL- and CL-type Liuqianxin A. Length of the first internode to the top and plant height were associated with the abortion degree of pollens, and the severer abortion led to shorter panicle neck protruding from the flag leaf sheath. As a result, panicles were enclosed by flag leaf sheath in WA-type Liuqianxin A; but such a characteristic was not found in other types of Liuqianxin A. In the 4 types of Liuqianxin A, the WA type had the lowest outcrossing rate due to sporadic flowering, distinctly laggard flowering time, and stretched flowering duration. The flowering habits and outcrossing rate were similar in the HL- and CL-type Liuqianxin A, which had no significant differences to the BT type. The restorable characteristic was the best in BT-type Liuqianxin A, followed by the HL and CL types, and the worst in the WA type. The HL- and CL-type CMS lines are proposed to replace the BT-type CMS line in japonica hybrid rice breeding because they have advantages on balancing the sterility, flowering habits, and restorable characteristic. Furthermore, the HL- and CL-type japonica restorers can be selected from the BT-type restorers.

摘 要为探讨小麦骨干亲本碧蚂4号的遗传构成及其特异位点在衍生后代中的传递特点, 利用覆盖小麦全基因组的1 239个SSR、EST-SSR和STS标记对碧蚂4号子一代衍生品种(系)的4个亲本进行标记筛选, 获得33个特异标记可用于76份碧蚂4号衍生材料的分析。在子一代和子二代材料中, 除标记Xgwm577外的32个标记均能扩增出碧蚂4号特异带, 且分别有8个和10个标记位点的传递频率大于50%; 在子三代和子四代材料中能扩增出碧蚂4号特异带的标记分别有29个和20个, 传递频率大于50%的标记位点分别有8个和4个; Xgwm261、Xedm80、SWES222和CFE223在4个世代中的传递频率都保持在50%以上; 有18个标记位点对衍生品种(系)的遗传贡献率大于25%; 推测这些基因组位点及其附近的染色体区域可能是被育种家强烈选择的部分, 碧蚂4号含有一些特殊的与重要农艺性状相关的基因组位点/区段, 可能是其成为骨干亲本的遗传基础。