Effects Of Carbon Nanotube Treatment On The Proliferation,Growth Of Protocorm Like Bodies And Its Mechanisms In Oncidium

Oncidium,also known as the dancing orchid and so on,is the generic term of the plant of Orchid-Epidendroideae-Oncidium.It has highly ornamental value because of its beautiful flower type,gorgeous and rich color,and slender stalks.Oncidium's seedling production generally done by tissue culture.The technology of tissue culture for orchid is relatively mature after it goes through decades development.it was found that different basal medium,different concentrations and proportions of growth factors,different organic additives,different culture containers and different carbon sources all show important effects on tissue culture of Oncidium.Carbon nanotube(CNT)is a new type of nanometer materials,which have special properties such as small size,light quality.CNTs are widely used in aerospace,electronics,chemical,pharmaceutical and other industries.In recently,CNTs were applied to agriculture,such as to explore the effect of CNTs on crop growth.But so far,CNTs hasn't been tested in PLBs culture in Oncidium yet.This study innovatively applied CNTs to the tissue culture of Oncidium,and explored the effects and functional mechanisms of different concentrations of CNTs on the growth of PLBs and seedling.The results are listed below.1.CNTs promoted PLBs growth,PLBs differentiation and seedling rooting and elongation.That 25 mg·L-1 of CNTs could optimally promote PLBs proliferation,and the best promotion effect was found in the liquid culture system.However,if the concentration of CNTs gone up further,its positive impact on PLBs growth would be reduced.The most weak promotion effect was observed when 100 mg·L-1 of CNTs was applied.PLBs of Oncidium gave the best differentiation parameters when cultured in differentiation medium included 50 mg·L-1 of CNTs.Similarly,high concentration of CNTs showed weak effects on PLBs differentiation.In following seedling culture,25 mg·L-1 of CNTs is identified as the most appropriate concentration for generating strong seedling,and 50 mg·L-1 of CNTs is the optimal concentration to promote rooting.In adition,CNTs additive inhibited the normal tillering of Oncidium seedling,and the inhibition effect would be enhanced with the increase of application concentration.2.CNTs affected the normal metabolism of Oncidium PLBs,activating the activity of antioxidant enzymes.Compared with the control group,the ultra oxygen anion producing rate and MDA content of CNTs treatment group were higher than the control group in the early and middle treatment stages,and all parameters increased with the extension of treatment time.In the late treatment stage,ultra oxygen anion producing rate and MDA content increased rapidly in the control group,while decreased in CNTs group and the 25 mg·L-1 treatment group give the lowest parameters.The soluble sugar content in CNTs treatment group also showed an increase-decline pattern in the earlier and middle treatment stage and was higher than the control group,while lower than the control group in the later stage.The average of soluble protein contents of all CNTs treatment groups were relatively lower.And 50 and 100 mg·L-1 of CNTs treatment groups were lower than that of control group in most of traetment time,and 25 mg·L-1 CNTs gave the highest soluble protein contents.3.Histological observation of different stages of Oncidium PLBs treated by different concentrations of CNTs through staining paraffin section.There were reunited CNT particles in the internal or on the surface of PLBs after treating with CNTs.This result showed that CNTs could go into cells,thus affecting the metabolism of cells.