Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/19/2010
Publication Date: 10/1/2010
Citation: Nagahashi, G., Douds, D.D., Yurdagul, F. 2010. Functional categories of root exudate components and their relevance to AM fungal growth. In: Koltai, H., Kapulnik, Y., editors. Arbuscular Mycorrhizas: Physiology and Function. p. 33-56. Interpretive Summary:
Technical Abstract: It is well established that plants grown under limited phosphorus (Pi) conditions are more readily colonized by arbuscular mycorrhizal (AM) fungi. It is also known that certain components of host root exudates can stimulate hyphal growth and branching of AM fungi and these compounds are elevated when the host is grown under Pi stress. To obtain a more general picture of the types of compounds exuded by host roots that effect the growth of AM fungi, a global analysis was performed on crude exudates of Ri TDNA-transformed carrot roots grown in the presence and absence of Pi. The results show that there is a distinct population of exudate compounds that are elevated in the absence versus the presence of Pi. Putative identifications were made for some of these compounds from data obtained by Fourier Transform Ion Cyclotron Mass Spectrometry (FTMS). The results were then compared to components of biologically active fractions purified by two dimensional thin layer chromatography (2D TLC). The data selection was restricted to compounds that were initially identified to be elevated in the crude –Pi exudate. Functional categories of compounds including plant growth regulators, phenols, flavonoids, sesquiterpenoids, and hydroxy fatty acids were selected that had the most relevance to AM fungal/host interactions. The review of each category will be discussed in relation to new results obtained from FTMS and their involvement in presymbiotic growth of AM fungi.