Study on the growth effect of Chinese mustard（Brassica campestris subsp. chinensis L.）infected by Piriformospora indica
Date Issued
2009
Date
2009
Author(s)
Lee, Yin-Chen
Abstract
Piriformospora indica (P. indica) is a new root endophytic fungus. It belonged to the Hymenomycetes of the Basidiomycota. P. indica interacts with the roots of various mono- and dicotyledonous plants, showing a positive effect on biomass production. In addition to this growth promoting effect, P. indica also has the potential to induce resistance to fungal disease and to increase the antioxidative activities of plants. Further more, after the infection of P. indica, plant becomes more tolerance to salt and drought. In this study, we used a model plant, Chinese mustard (Brassica campestris subsp. chinensis L.), for infection with P. indica. After inoculation for 7 days, Chinese mustard increased the amounts of lateral roots and root hairs. The fresh weight of plants, including above ground and under ground parts, were raised and the biomass of whole plants also became bigger. Screening with a subtractive cDNA library, we obtained a group of auxin-related genes. They can be classified into three parts: The first is related to cell wall acidification; the second is about auxin transport and the third is about auxin-signal transduction. These genes were in large up-regulated in the infected plant root. Moreover, the accumulated concentration of auxin in infected plant roots was higher than that in control plants. A transgenic Arabidopsis plant which has AUX1 gene-over expression was created. The transgenic plants have highly branched root systems and greater biomass than the wild type plants. We propose that the growth-promoting effect caused by P. indica is correlated with auxin metabolism.
Subjects
Piriformospora indica
AUX1 gene
acid-growth hypothesis
chemiosmotic hypothesis
auxin-signal transduction
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