AN EFFECTIVE IN VITRO PROTOCOL FOR INCREASING MYCORRHIZAL FORMATION RATE OF CATHAYA ARGROPHYLLA

Abstract

An effective in vitro ectomycorrhizal formation protocol of Cathaya argyrophylla, which is an endangered important tree belonging to the family Pinaceae, has been developed. Over 60% of the seeds germinated following 7 d on an agar medium that were treated by cutting and removing 1/5-1/3 of the seed coat and endosperms. A modified MS medium (MMS) containing 1/4 concentration of macro elements, 1/2 concentration of micro elements and full concentration of Fe salt and vitamins of the MS medium was used for seedling growth of C. argyophylla. An RM medium provided appropriate growth conditions for the hyphae of Cenococcum geophilum. The RM medium resulted not only in more rapid growth but also in progressively smoother fungal layers resulting in a thin homogeneous mycelia mat upon the medium surface. The growth of C. argyophylla on the MMS medium was compared to growth on the RM medium. The results showed that seedlings of C. argyophylla also grew well on the RM medium. Therefore, the RM medium was selected for in vitro ectomycorrhizal formation between C. argyophylla and C. geophilum. To solve the problem of sterilization of non_autoclavable containers, surface sterilization was achieved by 70% ethanol solution or 0.05% NaOCl solution followed by ultraviolet radiation. The results showed that all treated containers were sterilized and 87.5% of seedlings were mycorrhizal seedlings. This method will facilitate detailed studies on ectomycorrhizal development of C. argyrophylla and on ectomycorrhizal seedling applications.