Faculty of Education, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
Graduate School of Education, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
J Plant Res. 2021 Sep;134(5):921-931. doi: 10.1007/s10265-021-01311-6. Epub 2021 May 15.
We found mycoheterotrophic seedling growth (initial mycoheterotrophy) of Gentiana zollingeri, a spring-flowering photosynthetic species of Gentianaceae family. Small seeds (about 300 µm in length) were buried in a habitat by using seed packets, and development of the subterranean seedlings to form shoots, more than 3 cm in length, was observed in symbiosis with arbuscular mycorrhizal (AM) fungi in the dark (i.e., underground of a field). Hyphal coils and their degenerations were observed in the root cortical cells of the subterranean seedlings as well as those of adult plants. Among the mycobionts identified on the basis of partial small subunit rDNA sequences, it was found that AM fungi of a lineage in Glomeraceae dominantly colonized, and the AM fungi were also dominant in adult individuals of G. zollingeri in three habitats separated one another by 17.2, 34.7, and 49.6 km. Though initial mycoheterotrophy in symbioses with AM fungi has been observed in some pteridophytes, this is the first study to demonstrate this type of symbiosis in a photosynthetic seed plant. The mycoheterotrophy means that an energy distribution occurs through the hyphal bridges of AM fungi among different photosynthetic seed plants, which may be important in constructing plant species diversity in some ecosystems.
我们发现了獐牙菜（龙胆科獐牙菜属）幼苗的菌根异养生长（最初的菌根异养），这是一种春季开花的光合物种。我们使用种子包将小种子（长约 300µm）埋在一个栖息地中，并在黑暗中（即在野外的地下）观察到与丛枝菌根真菌共生的地下幼苗发育成超过 3cm 长的芽。在地下幼苗和成年植物的根皮层细胞中观察到菌根菌丝线圈及其退化。根据部分小亚基 rDNA 序列鉴定的菌根真菌中，发现丛枝菌根真菌在 Glomeraceae 中的一个谱系中占优势，并且 AM 真菌在三个栖息地的成年獐牙菜个体中也占优势，这三个栖息地彼此相距 17.2、34.7 和 49.6 公里。尽管已经在一些蕨类植物中观察到与 AM 真菌共生的最初菌根异养，但这是首次在光合种子植物中证明这种共生关系的研究。菌根异养意味着能量通过 AM 真菌的菌根桥在不同的光合种子植物之间分配，这在某些生态系统中构建植物物种多样性可能很重要。
