| Female sterile mutant FS-M1(Brassica. napus L.) was segregated from the cultivated variety Ningyou 10. A comparison between FS-M1 and its wild type Ningyou 10 was carried out by means of microscopic histological dissection and cytological observation. At the same time, the inheritance of female sterile of FS-M1 was studied. The main results were as follows:1,The floral morphology of FS-M1 differ in some aspects to that of wild type. Pistil length of FS-M1 was shorter than that of wild type. The 6 stamens of FS-M1 were almost equal to each other in length, while that of wild type composed of 4 longer one and 2 shorter one. There were two extra crescents-like organ developed at the ovary base of FS-M1 with missing nectars. Ovary shape and length of FS-M1 was more flat and shorter respectively than that of wild type. Stigma end of FS-M1 shaped a fork-like looking, was differ obviously from wild type.2,Result from the observation of agronomic trait of FS-M1 showed that: Pod set ratio of open-pollinated, artificial-pollinated, self-pollinated, sibling-pollinated, and constrained self-pollinated was about 3％respectively. Seed number per pod was about 2. It indicates that: female sterility of FS-M1 is steady. Seed set of hybrid from the cross of normal variety×FS-M1 was normal, so does open-pollinated of F1. Seed set ratio of self-pollinated of F1 was 97％, and seed per pod reached 21. It indicates that: the sterile pollens didn't affect the fertility of F1.3,The numbers of papillae cells of FS-M1 was sparse and its size was larger than that of wild type. Number of pollen grains observed on stigma of FS-M1 was less than that on wild type. The papillae cells of FS-M1 was drying and shriveling gradually in 2-3 days after flowering. There were few germinated pollens observed on surface of stigma of FS-M1 after hand-pollination. But no pollen tube found inside the style. Nevertheless there were pollen tubes existing inside the style of FS-M1, resulting in a normal seed-set when hand-pollination was made after excision of the stigma or part of the style. Results from above indicate that losing function of the papillae cells of FS-M1 resulting from its abnormal development is possibly a key factor causing the female sterility.4,Cytological observation of FS-M1 showed that chromosome number in somatic cells of FS-M1 was 2n=38 and its meiotic chromosome behavior in PMCs was normal. Chromosomes behaviour of PMs meiosis in cross of (FS-M1×1059) F1 and (FS-M1×N70) F1 were normal. Chromosomes were paired normally, and formed 19 bivalents at MI and divided evenly to the two poles at AI. It indicats that performance of the mutant is not results from chromosome variation.5,Genetic studies showed that the female sterility of FS-M1 was controlled by two pairs of recessive genes.
|
PDF Full Text Request