Genetic Comparisons Of Different Ploidy Common Buckwheat (Fagopyrum Esculentum Moench) And Their Rapid Propagation

Common buckwheat(Fagopyrum esculentum Moench) is the key cultivated buckwheat in genus Fagopyrum Mill(Polygonaceae). In this paper,the autotetraploid common buckwheat have been produced by means of the colchicine treatment of stem tips and doubling the chromosomes of 20 common buckwheat accessions.On the basis of these tetraploid and diploid accessions,the genetic differences of morphology,physiology and biochemical characteristics,and cytology between diploid and tetraploid were studied.Besides,the effects of different hormones on axinary bud induction,tufty bud differentiation,and rooting were studied by means of orthogonal design and common buckwheat stem segment explants with a knot.The main results were as follows:1.The result of doubling chromosomes showed that the optimal way to production of autotetraploid common buckwheat is to soak the seeds with 0.1%colchicine solution and then to treat the stem tip for 5 days with 0.2%colchicine +1.5%dimethyl sulfoxide solution,which produce the inductive rate of 39.13%. The tetraploid plants identified by morphology and cytology have the chromosome number 2n=4x=32.There are in all 22 new produced accessions of autotetraploid common buckwheat. 2.The morphological observation showed that there are obviously differences of agronomic traits between diploid and tetraploid.A new mutation character "elongation of the degenerated leaf in inflorescence" was discovered in progenies of colchicine treat plants.All 5 hybrids between autotetraploid long-style plants and homostyle autotetraploid plants were all shattering,different from their parents with non-shattering.3.Multiple comparison analysis showed that there are no significant differences of the contents of chlorophyll b, total chlorophyll,carotenoids and flavonoids in the leaves among the diploid,the common tetraploid,and the hybrid tetraploid common buckwheat,except the significant difference of the contents of chlorophyll a in leaves betweent diploid and common tetraploid buckwheat.The protein content of seeds in tetraploid buckwheat was significantly higher than the diploid.4.Cytogenetic observation showed that the diploid common buckwheat accessions all have 8â…¡in MI of PMC meiosis and common tetraploid and hybrid tetraploid common buckwheat have many various complex chromosomal pairing configurations with average chromosome pairing configurations 3.29â…£+0.13â…¢+ 8.88â…¡+0.71â… and 3.48â…£+0.10â…¢+8.64â…¡+0.50â… , respectively.The abnormal meiosis in tetraploid common buckwheat was observed much frequentlier than the diploid common buckwheat.The average number of univalent,the rate of abnormal diads,the rate of abnormal tetrads,the rate of multi-fission,and the sterile rate of pollen grains have significantly negative correlationship with the rate of seed set,indicating that the fertility was significantly influenced by the abnormal meiosis.5.The in vitro culture experiment showed that 6-BA is a major factor for induction of axianry buds and roots,and that TDZ is the key to induction of tusty bud.The optimal medium for inducing axillary bud development is MS₀+6-BA 1.0 mg/L+NAA 0.1 mg/L,producing the rate of axillary bud development of 67.9%.The MS₀ medium containing 6-BA 4.0 mg/L+TDZ 0.06 mg/L is better for inducing tufty bud with the differentiation rate of 166.7%.The optimum medium of root formation is 1/2 MS₀+ 6-BA 1.0mg/L+NAA 1.0 mg/L,which produce the rooting rate of 82.8%.