Tissue Culture And Dodecaploid Breeding Of Helianthus Tuberosus Linn

Helianthus tuberosus Linn is a perennial herbs in Helianthus L.of Compositae.It is a energy plant with great economic,medicinal,ecological and ornamental value.Plant polyploidization is an universal phenomenon in nature,and it is the propulsion of plant evolution.At present,the research about ploidy breeding of H.tuberosus Linn is none.The experimental with plant tissue culture and polyploid breeding in order to obtaining the tissue culture seedling of H. Linn and dodecaploid plants.The significance of this is that on the one hand offering theory and technology support for the scale production,and further studying on the genetic character and new germplasm cultivation has important theoretical and practical significance,on the other hand,utilization method of mmersion induced by colchicine,to feel the proper inducing conditions and get the dodecaploid which has great economic,ecological and ornamental value,to supporting materials well based for research about ploidy of H.tuberosus Linn.The result of experimental as follows:The axillary bud on young shoot of H.tuberosus Linn was used as explants,adding different concentration of plant hormone combinations on minimal medium(MS),to carry out tissue culture. The results showed that:the best disinfectant time by 0.1%HgC12 was 6 min and by 75%ethanol was 20 s.The Initial medium based on MS+6-BA0.5 mg/L+NAA0.1 mg/L medium.The optimizing medium for subculture multiplication is MS+6-BA1.0 mg/L+NAA0.01 mg/L.The optimum culture medium for strong seedling is MS+6-BA0.08 mg/L.Rooting culture:MS+NAA0.1 mg/L is the best one in rooting culture,the rooting rate is 91.7%.Adopted different concentration of gennfree colchicine and different time to treat buds.The results indicated that dodecaploid plantlets were obtained by treatment with 0.2%colchicine for about 72 hours,the dodecaploid induction rate only reached 10.0%.Lower or higher concentration of colchicine was ineffective.In addition,it is necessary that the buds are cultured in the new culture medium to avoid the production of chimera,because Helianthus tuberosus Linn grew slowly after inducting.There are difference between the hexaploid and dodecaploid by research.The results as follows: on the external morphology,the leaf of dodecaploid is thicker and greener,the intemode of plant is shorter;the leaf of hexaploid is thinner,the intemode of plant is longer.The thickness leaves,leaf index of hexaploid are 65%,183%of those the dodecaploid respectively.On the cell morphology,the guard cell of dodecaploid are bigger than hexaploid,length and width of dodecaploid are 149.88%, 143.22%of those the dodecaploid respectively.The number of chloroplast and chlorophyll content in the dodecaploid are more than hexaploid,stomatal density are lower than hexaploid.By comparing the stress resistance of hexaploid and dodecaploid,it is found that cold,drought and heat resistance of dodecaploid are stronger than hexaploid.