小麦BNS雄性不育显性遗传方式的观察与分析

BNS(Bai-Nong sterility)是一个对温度敏感的小麦雄性不育系,有完全的不育性和高自身转换性,在小麦杂交育种中有重要利用价值。为探讨该不育系的遗传方式,用该不育系与455个正常可育小麦品种杂交,结果发现F_1代套袋自交结实率从0到91%非正态连续分布,平均值24.52%,其中与BNS自交结实率相同的高不育组合占总组合数的15.42%,达到父本育性水平的高恢复组合占0.88%,其余是由低到高的部分不育组合。用F_1典型不育组合正反交,结果发现反交组合自交结实率虽提高显著,但远不达可育水平,仍是不育类型,表明BNS是核不育,不是质核互作不育。在核不育模式下,由于F_1有大量不育组合,表明BNS的不育性在F_1具有显性特征,由于F_1也有完全恢复组合,表明这些组合的父本中有恢复基因,且是非等位的。因此,BNS的不育性应是显性不育和非等位显性恢复的遗传模式。用F_1典型不育组合的F_2估计不育主效基因是2对,典型恢复组合F_2估计恢复主效基因也是2对。在2对显性不育基因和2对显性恢复基因的核遗传方式下,推断BNS、不育保持父本、不育恢复父本的基因型,然后用自交法和测交法检测后代分离,其中测交法用BNS测交可育组合的F_1基因分离,用无恢复基因的"郑麦366"测交不育组合F_1基因分离,4年共观察了16个F_2自交组合,20个Ft测交组合,结果表明,F_2和Ft的自交结实率不育与可育分离比与理论期望分离比均吻合,说明BNS的"显性不育和非等位显性恢复"遗传模式成立。

Observation and Analysis of Dominant Genetic Pattern of BNS Male Sterility in Wheat (Triticum aestivum L.)

BNS (Bai-Nong Sterility) is a new type of thermo-sensitive male-sterile wheat line. It has complete sterility and high self-conversion. So it is of great application value for wheat cross-breeding. In order to reveal BNS genetic pattern, a total of 455 normal fertile wheat varieties were crossed with this sterile line. The results showed that the self-seedset rate of F1 hybrids was continuously distribution,but non-normal, from 0 to 91% with average value of 24.52%. The high sterile combinations with self-seedset rate as same as BNS accounted for 15.42% of the total combination number, and the high recovery combinations with the self-seedset rate as same as father parent was only 0.88%. The others were part-sterility with the sterility from low to high. When typical sterile combinations were crossed reciprocally, it was shown that the seedset rate was increased, but it was still low fertile type, and far from fertile level, which indicated that BNS was genic male sterility (GMS), not cytoplasmic-nuclear male sterility(CMS). Under the model of GMS, the results that there were a large number of male sterile combinations in F1 meant that the sterility of BNS was dominant, and the results that there were also complete recovered combinations in F1 indicated that there was restorer gene(s) in father parent, which was non-allelic of sterile gene. Therefore, the genetic pattern of BNS sterility should be dominant sterility and non-allelic dominant recovery. By the segregation in F2 of typical sterile combination, two pairs of sterile major genes were estimated. And by the segregation in F2 of typical restoration combination, two pairs of restorer major genes were also estimated. According to the numbers of sterile and restoring genes, the genotypes of BNS, male sterility maintaining parent, male sterile restoring parent were inferred respectively. Then these genotypes were tested with the methods of self-cross and test-cross. Using the test-cross method, the gene segregation in F1 of fertile combinations were tested by BNS, and sterile combinations were tested by "Zhengmai 366" that was a maintaining sterility father parent. A total of 16 F2 and 20 Ft were observed in 4 years. The results showed that there was no significant difference between the observed segregation ratio and the expected theoretical segregation ratio of the self-seedset rate in F2 and Ft, suggesting that the genetic model of “dominant male sterility and non-allelic dominant restoration of male sterility” for BNS was verified to be established.