Tropentag, September 17 - 19, 2014 in Prague, Czech Republic "Bridging the gap between increasing knowledge and decreasing resources"

Changes in Magnaporthe oryzae Transcriptome During Rice Infection at High Temperature

¹Georg-August-Universität Göttingen, Dept. of Crop Sciences, Germany
²Erfurt University of Applied Sciences, Horticulture - Plant Production and Climate Change, Germany
³Africa Rice Center, Benin

Abstract

Future predictions indicate that extreme annual daily maximum temperature will increase by about 1–3ºC by mid-twenty-first century and by about 2–5ºC by the late twenty-first century. Such changes are predicted to lead to evolution of new pathogen strains, increase pathogen populations, spread of the diseases to new areas and increase susceptibility of plants. Rice blast, caused by Magnaporthe oryzae is the most destructive disease of rice worldwide. M. oryzae infects rice by regulating protein secretion, which enables the pathogen to either avoid recognition by the plant resistance proteins or to turn off the plant defenses. It is expected that elevated temperature may affect the biological processes leading to pathogenicity in M. oryzae. However, the direction of high temperature effect on pathogen fitness is not well understood. Here, we analysed the effect of temperature on the transcriptome of M. oryzae during invasive growth in the rice cultivar Nipponbare at 35ºC and 28ºC. We detected a higher number of putative effectors in plants exposed to 35ºC than in plants infected at 28ºC. The same was found for classical cell wall degrading enzymes. The qPCR relative quantification of in planta fungal biomass did not indicate any difference between 28ºC and 35ºC. However, plants grown and inoculated at 28ºC showed delayed symptom development in contrast to 35ºC, indicating that high temperature hastened biological processes geared towards necrotrophy more than normal temperature. Additionally, elevated temperature induced morphological transitions of M. oryzae during growth on the host, which could be related to survival and virulence dynamics.

Keywords: High temperature, Magnaporthe oryzae, pathogenicity, rice

Contact Address: Kerstin Wydra, Erfurt University of Applied Sciences, Horticulture - Plant Production and Climate Change, Leipziger Str. 77, 99085 Erfurt, Germany, e-mail: kerstin.wydrafh-erfurt.de