Reaction of wheat plants and alternative hosts to Magnaporthe oryzae

Lucas Gustavo Yock Durante,Jessica Evangelista De Souza,Lilian Maria Arruda Bacchi,Felipe André Sganseria Graichen

doi:10.1590/1808-1657000952017

Abstract

ABSTRACT: Blast disease, caused by the fungus Magnaporthe oryzae, has a major impact on wheat farming. The study of plant responses to pathogens has improved the management of this disease. Moreover, it is important to identify potential host plants in the crops’ vicinity and to understand reactions caused by plant-pathogen interactions. The objective of this study was to assess the histopathology of wheat plants, Digitaria insularis and Digitaria sanguinalis inoculated with M. oryzae isolates obtained either rice or wheat plants. Thirty-three days after sowing, greenhouse-grown plants of all three species were inoculated with each M. oryzae isolate. The observed effects (48 hours after inoculation) differed depending on the particular interaction between each pathogen isolate-plant species pair. For instance, wheat and D. sanguinalis had the weakest defensive response against spore germination, production of melanized appressoria, and appressorial penetration, with average values above 87, 90, and 43%, respectively, for these events in these plants. Furthermore, germination and appressoria melanization were more aggressive in the rice isolate than in the wheat isolate. Additionally, evidence for a defensive response (such as cell death) was observed in wheat plants inoculated with rice isolates. However, such a response was absent in plants inoculated using wheat isolates, presumably because pathogen recognition failed.

Highlights

IntroductionIn Brazil, it was initially established in the coldest regions of the country, in the states of Rio Grande do Sul, Santa Catarina, and southern Paraná
Common wheat Triticum aestivum L. is the most widespread crop in the world
Blast disease is of significant importance in wheat farming, and it is caused by the fungus Magnaporthe oryzae B

Summary

Introduction

In Brazil, it was initially established in the coldest regions of the country, in the states of Rio Grande do Sul, Santa Catarina, and southern Paraná. In 2016, Brazil produced 6.7 million tons of wheat in 2.1 million hectares (CONAB, 2017). Blast disease is of significant importance in wheat farming, and it is caused by the fungus Magnaporthe oryzae B. In 1637, this disease was initially reported in rice farms in China and Japan (BEDENDO; PRABHU, 2005). In 1985, the first wheat infection was reported in Brazil, in the north of Paraná (IGARASHI et al, 1986), and since it has been found in other producing regions of the country, as well as other LatinAmerican countries. Various aspects related to this disease have been the object of study, including optimal infection temperature, dissemination of the pathogen, application of fungicides, and even sources of resistance in wheat cultivars and host-pathogen interactions (URASHIMA et al, 2007; CRUZ et al, 2010)

Objectives

Methods

Results

Conclusion