Studies On The RAPD Marker Linked To The Restorer Gene And Endogenous Hormone Contents Of A Cytoplasmic Male Sterile Pepper(Capsicum Annuum L.)

Pepper (Capsicum annuumL.) is a major vegetable in china. Pepper shows the remarkable heterosis. Hybrid seed production by the help of cytoplasmic male sterility is an important way to utilization of heterosis in pepper. Basic researches of cytoplasmic male sterility in pepper lack compared to the applied researches and clearly lag behind these of cytoplasmic male sterility in such crops as maize and rice. Using the CMS 9704A and its maintainer 9704B, the restorer line 8001 and 9704AX8001 F,, F, as the materials, we carried out the genetic studies of fertility restoration, molecular mapping of the restorer gene and determination of hormone contents in leaves and floral buds at the developmental stages in order to enrich the understanding of cytoplasmic male sterility, quicken the breeding of the restorer lines and to overcome the unstability of male sterility due to the sensitivity to low temperature in pepper. The following conclutions have been drawn:1. Observation in male fertility of the CMS line 9704A,the restorer 8001 and 9704AX8001 F, and F,, populations showed that the fertility restoration of the CMS line 9704A is controlled by a single dominant gene.2. The CMS line 9704A, the restorer 8001 and F, population of 9704AX8001 containing 120 individual plants were used for molecular mapping of the restorer gene by bulked segregant analysis (BSA). 515 decamer primers with arbitrary sequences were chosen for polymerase chain reaction amplification. It is found that the polymorphism between the parents could be detected by 43. 8% of the primer and one RAPD marker OPL09-76I was tightly linked to the restorer gene of the restorer 8001 with the overcross value of 4.17% and genetic distance of 4. 18cM. The marker was repeatable and easy to score. The r.arker band was cloned and sequenced. The sequence of the marker band is compared for homology with the nucleotide sequences in GenBank by BLAST program, with no highly homology sequences found.3. The top 2 leaves from the plants of 9704A, 9704B, 8001 and 9704AX8001 F, were collected at 3 different developmental stages:seedling, initial and full blossom stages . The floral buds collected from the above materials at the full blossom stage were classified into 6 groups according to the size and morphology of the floral buds. The all samples were extracted with 80% methanol and determined for contents of IAA^ ABA GA, and iPA by indirected ELISA. The results indicated that: (1) The CMS line and its maintainer had the distinctive change patterns and different contents of IAA, GA ABA iPA and ZR in floral buds. Contents of IAA and G were higher and contents of iPA and ZR were lower of CMS line than of the maintainer in floral buds, but contents of ABA was higher at early stages of floral buds development and lower at late stages. (2) Except for ZR, the changes of IAA GA, ABA and iPA in the leaves of the CMS line 9704A followed the pattern identical to the maintainer line from seedling stage to full blossom stage, but the hormone amplitude and contents were different greatly. Compared with the maintainer line, the CMS line had lower IAA ABA and iPA contents and almost same GA:1, and ZR contents in leaves at seedling stage, higher ABA and GA3 contents and lower IAA, iPA and ZR contents at initial blossom stage , higher contents of all the hormones tested at full blossom stage. (3) The first filial generation generally showed heterobeltiosis in hormone contents of leaves and floral buds. The results suggested that the changes of endogenous hormones contents were closely related to the occurrence of cytoplasmic male sterility.