Study On Hereditary Stability By Vegetative Propagation And CDNA-SRAP Of Fagopyrum Dibotrys Mutants

Buckwheat (Fagopyrum dibotrys (D. Don.) Hara.) belongs to Fagopyrum genus of Polygonaceae family, its rhizome have function on tumor inhibition and anticancer. It had been one of the "list of national key conservative wild plants in China (the first group)" because of destruction by blind harvest and environment pollution. Buckwheat propagates mainly by asexual mode, and it becomes difficult create new genotypes by traditional breeding.Buckwheat rhizomes of Jiangsu Ⅱ were irradiated by gamma ray.Red stem and red leaves mutants were induced in M2generation. Agronomic traits, photosynthesis, antioxidative enzymes and (-) epicatechin of selected green and mutants were studied in the paper during2008to2009, and isoenzyme and chromosome were researched as well, and cDNA-SRAP technology was applied for genetic diversity and differential gene expression. Results showed as followed:(1) The growth process of mutants was retarded, and it was longer in plants propagation by cuttings than propagation from rhizome. The rhizome rapid growth was between July and August, and reached higher dry and wet weight in October. The plant height of green stem buckwheat was the highest, and red stem had the most branches, while the red leaves buckwheat leaf area were the biggest. Root yield of green stem buckwheat was higher than red stem and the difference reached extreme significant level. Branches and main stem of green and red stem have negative correlation with root yield. The results showed agronomic traits and growth process were almost stability heredity.(2) The activity of SOD, POD, CAT and APX increased accompany with plant growth, the activity of mutants were higher than green stem during seeding stage and growth stage. Two additional bands was found in distal isozymogram of POD of red leaves, while there were three bands on proximal during seedling stage in red leaves and green stem, but red stem had two bands; During growth stage, the green stem had four bands; while the mutant has three during flowering stage,; all had four bands, but one of the green stem had different mobility. The bands number of SOD and CAT was unchanged.The results showed antioxidative enzymes and isozymogram changed regularly among different descends, which indicated that heredity of the mutants were stability.(3)The photosynthetic pigments were higher during growth stage, and lower during seedling stage and flowering stage. The pigments of green leaves were higher than mutants. The ratio of Chla/Chlb varied as'low-high-low', and the red leaves were the highest during seedling stage and growth stage. Anthocyanin content and flavonoids in the green and red stem were always increasing, while anthocyanin content of red leaves were decreased, and flavonoids varied as red stem, but the anthocyanin content and flavonoids in the green were lower.Pn of green stems was higher than mutants, and it reached significantly during seedling stage and decreased dramatically during flower period. During seedling stage, Pn and CE of green stem were higher than mutants and increased as plant growth. Anthocyanin content of red leaves had negative correlation with Pn, CE and Fv/Fm, which indicated the existed of anthocyanin suppressed the red leaves photosynthesis. The diurnal net photosynthetic rate exhibited double-peak pattern during growth stage, which was caused principally by stomatal limitation and midday depression were appeared. The research indicated mutants had lower photosynthesis capacity than original plants.The Fv/Fm, qP,ΦPSⅡ and ETR of mutants were lower, and the red stems were lowest, and NPQ of red stems were highest while the green stems were lowest during seedling stage and growth stage. But during flowering stage, NPQ of green stems increased and qP and ΦPSⅡ lowered, this may be induced by leaves senescence.The trend of photosynthetic pigments and photosynthetic characteristics and chlorophyll fluorescence varied as the same from2008to2009, which indicated the heredity were stability.(4) The results of karyotype analysis showed that the green stem was2n=2x=16=12m+4sm, red stem was2n=2x=16=10m+6sm(2SAT), and the red leaves was3n=3x=24=15m+9sm(3SAT). All was belong to2A type, according to the Stebbins' karyotypic classification method.(5) Active ingredient of buckwheat accumulated swiftly in June and August. Active ingredients in red leaves were higher than green and red stems, and red stems were lowest. It reached0.034%in green stems and0.038%in red leaves and0.021%in red stems. Active ingredient in plants propagation from cuttings was lower than propagation from rhizome.(6) The RT-PCR and Sequence-related amplified polymorphism (SRAP) was used for analysing differential gene expression.26primer pairs were selected from49primer pairs, and amplified576polymorphic bands with an average of41.7%polymorphic bands per primer pair. Part differential expression bands were cloned and analysised, two special cDNA fragments were found in mutant, and one band had relationship with aspartate aminotransferase.