Reaction of wheat plants and alternative hosts to Magnaporthe oryzae

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.

Hydrogen Peroxide Detoxifying Enzymes Showed Different Activities at Different Timing in Host and Nonhost Plants Interactions with Wheat Blast Fungus Magnaporthe Oryzae Triticum Pathotype

“…Infected seeds are considered the primary source of long-range inoculum dispersal of M. oryzae from one place to another [9]. Besides seed, alternative hosts are also considered as a reservoir of overwintering inoculum of blast pathogen for disease outbreak [10]. A striking example is wheat blast outbreak in Brazil, which was the consequence of host jump of MoT isolates from perennial ryegrass due to loss of a host specificity determinant [11].…”

“…For an efficient management strategy, it is important to determine the susceptibility of other plants especially close relatives of wheat to MoT isolates. These plants may serve as an overwintering reservoir of the pathogen and produce copious amount of conidia as alternative host plant [10]. We have previously shown that Bangladesh MoT isolates could develop symptoms on barley [2].…”