Bypassing both surface attachment and surface recognition requirements for appressorium formation by overactive ras signaling in magnaporthe oryzae

Xiaoying Zhou, Xinhua Zhao, Chaoyang Xue, Yafeng Dai, Jin Rong Xu

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Magnaporthe oryzae forms a highly specialized infection structure called an appressorium for plant penetration. In M. oryzae and many other plant-pathogenic fungi, surface attachment and surface recognition are two essential requirements for appressorium formation. Development of appressoria in the air has not been reported. In this study, we found that expression of a dominant active MoRAS2G18V allele in M. oryzae resulted in the formation of morphologically abnormal appressoria on nonconducive surfaces, in liquid suspensions, and on aerial hyphae without attachment to hard surfaces. Both the Pmk1 mitogen-Activated protein kinase cascade and cAMP signaling pathways that regulate surface recognition and appressorium morphogenesis in M. oryzae were overactivated in the MoRAS2G18V transformant. In mutants deleted of PMK1 or CPKA, expression of MoRAS2G18V had no significant effects on appressorium morphogenesis. Furthermore, expression of dominant MoRAS2 in Colletotrichum graminicola and C. gloeosporioides also caused the formation of appressoriumlike structures in aerial hyphae. Overall, our data indicate that MoRas2 functions upstream from both the cAMPPKA and Pmk1 pathways and overactive Ras signaling leads to improper activation of these two pathways and appressorium formation without surface attachment in appressorium- forming pathogens.

Original languageEnglish (US)
Pages (from-to)996-1004
Number of pages9
JournalMolecular Plant-Microbe Interactions
Volume27
Issue number9
DOIs
StatePublished - Sep 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Agronomy and Crop Science

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