Effects Of Mycorrhizal Fungi On The Growth, Development And Gene Expression Of Dendrobium Candidum And D. Nobile

Effects of mycorrhizal fungi on the growth, development and gene expression of Dendrobium candidum Wall, ex Lindl. and D. nobile Lindl. were studied in vitro culture, including technology of protocorm suspension culture, the effects of mycorrhizal fungi on the growth and morphology of D. candidum and D. nobile and on the gene expression of D. nobile.The growth of D. candidum protocorms in liquid medium was markedly better than that in solid medium (P<0.001). Among four basic media MS, 1/2MS, 67-V and B5, the 67-V was best for growth of protocorm. Effects of sucrose and potato extract, nitrate and ammonium, inoculum and medium volume on the growth of protocorm was studied using orthogonal design. The results indicated that 67-V medium supplied 30 g/L sucrose, 200 g/L potato extract, 100 mg/L (NH₄)₂SO₄, and 800 mg/L KNO₃ was best for the growth of protocorm when 100 ml liquid medium was put in 250 ml flask and inoculum was more than 6 g/flask. The secondary metabolites were markedly test from protocorm cultures by TLC analysis. The effect of different fungal elicitors was distinct on polysaccharides content of protocorm cultures, while their effect on the growth of protocorm was not significant (P>0.05).Effects of fungus AR-18 or AR-15 (Epulorhiza sp.) on the growth of D. candidum and D. nobile were studied in vitro culture. In agar medium, effects of AR-18 or AR-15 on fresh weight and dry weight of D. candidum and D. nobile were not significant (P>0.05). However, in vermiculite medium, the effect of AR-18 or AR-15 on fresh weight of D. nobile was significant (P<0.05) or very significant (P<0.01), respectively. Fresh weight of D. nobile inoculated with AR-18 or AR-15 was increased by 16% or 64% compared with the non-inoculated ones (control), respectively. The effect of AR-18 or AR-15 on dry weight of D. nobile was very significant (P<0.01) or...