Studies On The Micropropagation Of Wasabi (Wasabi Japonica Matsum)

Wasab[(Wasabi japonica Matsum),which originally grows in Japan and China, is a rare worldwide vegetable used both for culinary and medicinal purpose, in recent years as the development of peoples' living condition, the need for wasabi products greatly increases each year. Now one of the main problems in planting wasabi is the production of wasabi seedlings. In order to resolve this problem, a shoot-tip culture system has been established. However ,in this system , the contamination ratio of explants in initial culture is very high and the proliferation rate of plantlets is very low and the culture cycle is very long, all this limits its practical use.This study focuses on optimizing shoot-tip micropropogation system, some work on wasabi callus induction, multiplication and diffrentiation is also involved in it.1.optimizing shoot-tip micropropogation system1.1 In initial cultureEffects of sterilizing process, plant growth time and cultivation mode on contamination ratio and plantlet growth were studied, germ-free plantlet ratio was up to 52%.Shoot-tips and accessory buds for initial culture were often derived from field-grown wasabi plants, wasabi seeds were firstly used to culture for shoot-tip micropropogation. By this new method, the germ-free plantlet ratio was increased to 72% and plantlets grow better.1.2 In multiplication cultureIn order to improve plantlet propogation and growth, the effects of different media and new hormone (TDZ and 2ip) were investigated, inorganic substrate and two-phase culture method were firstly applied in wasabi multiplication culture. The results demonstrated that MK medium containing 2ip 1.0mg/L,NAA 0.05mg/L and the substitute of inorganic substrate(vermiculite/perlite = 2/l) for agar in culture medium were better for plantlet growth, and the two-phase culture method was excellent both for plantlet propogation and growth. The combination of MK medium(2ipl.O+NAA0.05) and two-phase culture method could advance proliferation rate from 3-4 to 7-8 andcould help plantiet grow best.1.3 In rooting and acclimatizationIn rooting culture, 0.2 NAA and inorganic substrate(vermiculite/perlite = 2/l) used in culture medium were suitable for root development and growth. In acclimatization, effects of rooting culture time and cultivate substrate on plantlet's survival ratio and growth were studied, the results showed that plantiet without rooting culture was better for acclimatization, and the organic substrate (reed residue) was outstanding for plantiet growth.2. primary study on wasabi callus culturethe conditions of wasabi callus induction, multiplication and diffrentiation were investigated, the results demonstrated that young petiole was suitable for callus induction, which should be done under 25 癈 and in darkness, TDZ could efficiently induce callus; the combination of 1/2MS(0.2TDZ+0.4NAA) containing 3mg/L AgNo3 and solid-liquid alternation culture is best for callus multiplication and diffrentiation.