A Study On Tissue Culture And Plant Regeneration Of Rare And Endangered Plant Helianthemum Ordosicum

Helianthemum ordosicum is a rare and endangered relic species of the Tertiary PaleoMediterranean flora with a narrow distribution area.In this study,the aseptic seedlings and adult plants were used as experimental materials,controlling the directional differentiation of explants by changing the concentration and proportion of exogenous hormones.The suitable medium types and hormone groups at different growth stages were tested.The effects of light,pH and explants types on the tissue culture of were discussed.The regeneration system of tissue culture was established.This study is of great significance for the conservation germplasm resources.The main results and conclusions are as follows:1)Aseptic seedlings cotyledons,leaves,stem apexes,non-bud stems,stem with axillary buds and adult plants leaves,stem apexes,young non-bud Stems,stem with axillary buds can produce sterile seedlings through tissue culture.Aseptic seedling roots,adult plants lignified stem segments and roots can not can produce sterile seedlings through tissue culture.2)The optimum light intensity for inducing proliferation 43-58?mol·m^-2·s^-1and differentiation of callus is 45-58?mol·m^-2·s^-1,The optimum light intensity for rooting culture is 55-70?mol·m^-2·s^-1.Increasing the ratio of red light can slow down the browning rate.Inducing proliferation,differentiation of callus and rooting culture the growth of explants was the best in the range of 5.8.3)The best explants disinfection method:the seeds soaked in 75%alcohol for30 s,soaked in 0.5%NaClO₄ 8 min,soaked in 0.1%mercuric chloride 8 min.The difficulty of sterilization was different for explants physiological states and material picking reason,June to August is the suitable sampling time,the sterilization effect of new leaves is better than old leaves.4)The aseptic seedlings cotyledons,leaves and non-bud Stems were used as explants,The optimal medium for callus induction and multiplication is:MS+8.0mg/L NAA+0.5 mg/L 6-BA;The optimal medium for adventitious bud differentiation is:MS+0.05 mg/L NAA+1.0 mg/L 6-BA;The optimal medium for rooting is:1/2MS+0.2mg/L IBA.The adult plants leaves and non-bud Stems were used as explants,The optimal medium for callus induction and multiplication is:MS+2.0 mg/L NAA+2.0 mg/L 6-BA;The optimal medium for adventitious bud differentiation is:MS+0.05 mg/L NAA+1.0 mg/L 6-BA;The optimal medium for rooting is:1/2MS+0.2mg/L IBA.The aseptic seedlings and adult plants stem apex and stem with axillary buds were used as explants,The optimal medium for differentiation of axillary buds is:MS+0.05 mg/L NAA+1.0 mg/L 6-BA;The optimal medium for rooting is:1/2 MS+0.2mg/L IBA.5)The morphogenesis pathway of the stem with axillary buds and stem apex explants of aseptic seedlings and adult plants is direct organogenesis;the embryoid pathway is cotyledon,leaf and non-bud stem tissue culture of aseptic seedlings,while the morphogenesis pathway of young non-bud stem tissue culture of adult plants still uncertain.