Tissue Culture And Polyploid Induction Of Yellow Nut-sedge (Cyperus Esculentus L.)

Cyperus esculentus L.is a perennial herb of Cyperaceae,which is often cultivated as an annual crop and reproduced by tuber in agriculture production.It can uniquely accumulate rich oil in tuber,and thereby can be used as an effective supplement of edible oil and as well as a new food source.Few varieties,small size and high harvest cost have become the important factors restricting the promotion of Yellow Nut-sedge.Therefore,it is important to cultivate improved varieties through biotechnology.In this study,bud proliferation,callus induction and regeneration and rooting induction were investigated through in vitro culture of Yellow Nut-sedge stem apex,to establish the rapid propagation and plant regeneration system of Yellow Nut-sedge.Meanwhile,Yellow Nut-sedge sterile seedlings were treated with the colchicine to establish colchicine-induced polymorphic technical system.It provides the technical methods and theoretical bases for the breeding and variety improvement of excellent Yellow Nut-sedge germplasm resources.The main results were as follows:(1)The orthogonal design method was used to investigate the effect of combination of different plant growth regulators(PGRs)on propagation of Yellow Nut-sedge plantlets.Our results showed that the effect of three PGRs(6-benzylaminopurine,kinetin and?-naphthaleneacetic acid)on the proliferation rate of plantlets was 6-BA > NAA > KT.6-BA significantly promoted the proliferation of cluster buds,while NAA had an inhibitory effect.In the range of tested concentration,the proliferation coefficient decreased with the increase of NAA concentration.Considering both of the proliferation coefficient and the growth of plantlets,the optimal PGR combination was: 1.0 mg/L 6-BA + 0.2 mg/L KT.After 4-weeks of cultivation,the proliferation coefficient of plantlet treated with the optimal PGR combination was 7.58.(2)Different concentrations of 2,4-Dichlorophenoxyacetic acid(2,4-D)have different effects on the induction and re-differentiation of callus of Yellow Nut-sedge.The results showed the higher the concentration of 2,4-D with the higher the callus induction rate,but the lower the callus re-differentiation rate.At the concentration of 2,4-D of 3.0 mg/L,it is optimal for the induction of callus of Yellow Nut-sedge,and when the concentration of2,4-D is 2.0 mg/L,it is most suitable for callus re-differentiation.(3)Meanwhile,we investigated the effect of different basic mediums and PGRs(Indole-3-butyric acid or NAA)on plantlets rooting.Considering the rooting rate,the rootnumber and growth status,we suppose that MS basal medium free of any PGRs is the most suitable medium for root growth,with the rooting rate up to 88.10% with an average root number of 2.04 per plant.(4)The effects of different colchicine concentrations and inducing time on polyploid induction of Yellow Nut-sedge were also studied.The results indicated that the induction effect was much better by soaking in 0.1% colchicines with 2% Dimethyl sulfoxide(DMSO)for 24 h,and the induction rate was 58.29%.Twenty nine tetraploid lines and 101 chimeric lines were identified by flow cytometry,and the biological characteristic of the tetraploid were observed and analyzed.