McCormick M K, Whigham D F, O'Neill J
Smithsonian Environmental Research Center, P.O. Box 28, Edgewater, MD 21037, USA.
New Phytol. 2004 Aug;163(2):425-438. doi: 10.1111/j.1469-8137.2004.01114.x.
• Specific orchid-fungal associations are known for nonphotosynthetic orchids but fungal diversity in photosynthetic orchids is thought to be quite broad. Specific fungal associations will figure prominently in conservation efforts, while diverse associations may require less attention. We combined culture techniques with ITS and mtLSU sequences and phylogenetic analysis to determine the genetic diversity of mycorrhizal fungi associated with an evergreen, a spring-green, and a winter-green orchid and compared this diversity with that published for a nonphotosynthetic orchid. • Mycorrhizal diversity in two of the three photosynthetic orchids was lower than for the nonphotosynthetic orchid. Mycorrhizal diversity in protocorms of the third species was also equal to, or less than, the fungal diversity associated with the nonphotosynthetic species, but adult fungal diversity was greater. • We found that photosynthetic orchids do not necessarily have more diverse mycorrhizal associations than nonphotosynthetic orchids. Similarly, evergreen orchids do not necessarily have greater mycorrhizal diversity than seasonally green orchids. Thus, orchid mycorrhizal diversity may not be determined by adult photosynthetic capacity.
• 非光合兰花存在特定的兰花-真菌共生关系，而光合兰花中的真菌多样性被认为相当广泛。特定的真菌共生关系在保护工作中将占据显著地位，而多样的共生关系可能需要较少关注。我们将培养技术与ITS和mtLSU序列以及系统发育分析相结合，以确定与一种常绿、一种春绿和一种冬绿兰花相关的菌根真菌的遗传多样性，并将这种多样性与已发表的一种非光合兰花的多样性进行比较。
• 三种光合兰花中的两种的菌根多样性低于非光合兰花。第三种兰花原球茎中的菌根多样性也等于或低于与非光合物种相关的真菌多样性，但成年真菌多样性更高。
• 我们发现，光合兰花的菌根共生关系不一定比非光合兰花更多样化。同样，常绿兰花的菌根多样性不一定比季节性绿色兰花更高。因此，兰花菌根多样性可能不由成年光合能力决定。
