Dramatic Transcriptional Changes in an Intracellular Parasite Enable Host Switching between Plant and Insect

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the “host switching” between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to “host switching” between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of “host switching” mechanism may contribute to the development of novel pest controls

ファイトプラズマ感染による不稔症状を引き起こす病原性因子に関する研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 難波 成任, 東京大学教授 河鰭 実之, 東京大学准教授 経塚 淳子, 東京大学准教授 山次 康幸, 法政大学教授 大島 研郎University of Tokyo(東京大学

Minimal anonimized SLCMV diagnostics data in Cambodia and Vietnam in 2016

The data includes diagnosis results of Sri Lankan cassava mosaic virus (SLCMV) from binational surveys of 15 districts in Vietnam and 16 districts in Cambodia, with 240 samples by district

Surveillance for Sri Lankan cassava mosaic virus (SLCMV) in Cambodia and Vietnam one year after its initial detection in a single plantation in 2015

Cassava mosaic disease, one of the ten most economically important crop viral diseases in the world, was first reported in Southeast Asia from a single plantation in Cambodia in 2015. To determine the presence and incidence of Sri Lankan cassava mosaic virus (SLCMV) one year after first detection, a total of 6,480 samples from 419 fields were systematically collected from cassava production areas across Cambodia (3,840 samples; 240 fields) and Vietnam (2,640samples; 179 fields) in the 2016 cropping season. Using PCR-based diagnostics, we identified 49 SLCMV-infected plants from nine fields, representing 2% of the total number of fields sampled. Infected fields were geographically restricted to two provinces of Eastern Cambodia, while no infection was detected from any of the other sampled sites in either country. Symptom expression patterns in infected plants suggested that SLCMV may have been transmitted both through infected planting materials, and by Bemisia tabaci, the known whitefly vector of SLCMV. In addition, 14% of virus infected plants did not express typical symptoms of cassava mosaic disease on their leaves, highlighting that molecular-based validation is needed to confirm the presence of SLCMV in the field. None of the owners of the SLCMV-infected fields indicated acquired planting materials from the plantation in Ratanakiri where SLCMV was first reported. The surveillance baseline data generated for both countries is discussed in light of future options to control and manage cassava mosaic disease

Minimal anonimized SLCMV diagnostics data in Cambodia and Vietnam in 2016

The data includes diagnosis results of Sri Lankan cassava mosaic virus (SLCMV) from binational surveys of 15 districts in Vietnam and 16 districts in Cambodia, with 240 samples by district

Lectin-Mediated Resistance Impairs Plant Virus Infection at the Cellular Level[C][W][OA]

This work identifies jacalin-type lectin that is responsible for resistance to multiple plant viruses belonging to the genus Potexvirus. The isolation and characterization of this lectin sheds light on a novel resistance machinery to plant viruses

Farmer surveys in Cambodia and Vietnam: cassava planting material use and exchange at national level with 4 district-level case studies

The data includes national surveys of 15 districts in Vietnam and 16 districts in Cambodia, with 15 responses by district. Districts were selected based on high cassava production density and expert input from local government officials. National surveys covered the following themes: (a) respondent information, (b) seed use overview, and (c) field and household data. In addition to the aforementioned categories, the subnational surveys collected data on (d) quality, (e) affordability/profitability, and (f) information sources