秋光 和也



領 域 名  植物科学    

教員氏名   秋 光 和 也 

研究分野 植物病理学 

研究キーワード:  宿主特異的毒素, 希少糖,ゲノム, ミトコンドリア, カンキツ

1.Alternaria属菌の生産する宿主特異的毒素生合成遺伝子

Alternaria属菌のいくつかの系統が生産する低分子の2次化合物に、宿主特異的毒素と呼ばれるものがある.宿主得的毒素が毒性を示す植物と,その毒素の生産菌が感染できる宿主範 囲は一致し,毒素生産能の消失は病原性の失活に直結する.本研究室では,デカトリエン酸エ ステル化合物(ACT毒素)とポリケチド化合物(ACR毒素)の宿主特異的毒素に着目し、これらの 生合成酵素や制御因子をコードする遺伝子群は,特定の小型染色体上にクラスター化して座 乗することが明らかにした.これらの遺伝子群の機能を,相同組み換えを介した標的遺伝子破 壊法やRNAサイレンシング法を用いて解析し,標的とする遺伝子産物の機能消失が毒素生産 の停止に直結することにより,毒素生合成に必須であることを証明してきている.

2.tRNA-Alaの介在領域修飾不全による植物ミトコンドリア病の発生機構

   宿主特異的ACR毒素のレセプターをコードするACRS遺伝子は,ミトコンドリアゲノムのtRNA-Alaの介在領域に座乗し, 非感受性品種ではプロセッシングにより修飾分解される.本研究室では, このプロセッシングを担うタンパク複合体の構成タンパクを網羅的に解析し,1.の研究とともに, 植物側・病原菌側の双方から特異性メカニズムの一端の解明を目指している.

3.希少糖の植物への作用とその作用機構の解明

   本研究は,農業生産分野に希少糖を利用したイノベーション創出を目指し,香川大学が有する独創的な希少糖研究シーズを活用して,関係企業と連携を図りながら,植物の生体防御や生長調節もしくは病原菌との相互作用において,希少糖の果たす作用機構の解明を試みている.さらに,希少糖を生産する植物であるズイナの組織培養法を確立し,ズイナの特性を担う生理・生化学・分子生物学的研究を進めている.

HP http://www.ag.kagawa-u.ac.jp/plantpathology/index.html

代表的な研究業績

Endopolygalacturonase is essential for citrus black rot caused by Alternaria citri but not brown spot caused by Alternaria alternata(2001) A Isshiki, K Akimitsu, M Yamamoto, H Yamamoto, Molecular Plant-Microbe Interactions 14 : 749-757.

Host-selective toxins produced by the plant pathogenic fungus Alternaria alternata (2012) T Tsuge, Y Harimoto, K Akimitsu, K Ohtani, M Kodama, Y Akagi, M Egusa, …, FEMS Microbiology Reviews 37: 44-66.

Molecular, ecological and evolutionary approaches to understanding Alternaria diseases of citrus (2003) K Akimitsu, TL Peever, LW Timmer, Molecular Plant Pathology 4: 435-446.

Sensitivity to Alternaria alternata toxin in citrus because of altered mitochondrial RNA processing (2002) K Ohtani, H Yamamoto, K Akimitsu, Proceedings of the National Academy of Sciences 99: 2439-2444.

The rare sugar D-allose acts as a triggering molecule of rice defence via ROS generation (2013) A Kano, T Fukumoto, K Ohtani, A Yoshihara, T Ohara, S Tajima, K Izumori, . K Akimitsu, Journal of Experimental Botany 64: 4939-4951.

Research Area: Plant Science

Research Specialization: Plant Pathology 

Name: AKIMITSU, Kazuya

Keywords: Host-selective toxin, Rare sugar, Genome, Mitochondria, Citrus

Recent Research

1.Biosynthesis gene cluster of Host-selective Toxin from Alternaria species

     Host-selective toxins are second metabolic compounds with a low molecular weight, which are produced by several different pathotypes of Alternaria species.  The host-range of toxin producer is equal to the host-selectivity of the toxin, and a loss of the toxin production leads a loss of pathogenicity. In our laboratory, we identified one dispensable chromosome carrying biosynthetic gene cluster for esters of 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid (ACT-toxin) and another chromosome carrying that for polyketide (ACR-toxin). Target gene disruption and RNA silencing of the genes in the respective cluster caused a loss of the toxin production and pathogenicity, indicating the necessity of these genes in the toxin production as well as the pathogenicity.

2.Mechanism for appearance of plant mitochondrial disease cause by disfunction in modification of internal region of tRNA-Ala

   ACRS gene encoding ACR-toxin receptor protein is located in the internal region of tRNA-Ala in mitochondrial genome, and the transcript of the region is processed in the toxin-insensitive cultivars of citrus.  We examine the processing protein complex of the receptor gene transcript, and qualify the mechanism of host selectivity from both pathogen and host sides.

3.Mechanism of rare sugar effects in plants

   Rare sugars give effects on plants; such as a transient growth inhibition and induction of defense-related gene expression. The mechanism controlling these effects was identified and we are  trying to use them for agricultural practices. Itea plant producing rare sugar is also examined on the processes of the sugar production as well as the evolutional role of rare sugar production.

HP http://www.ag.kagawa-u.ac.jp/plantpathology/index.html

References

Endopolygalacturonase is essential for citrus black rot caused by Alternaria citri but not brown spot caused by Alternaria alternata(2001) A Isshiki, K Akimitsu, M Yamamoto, H Yamamoto, Molecular Plant-Microbe Interactions 14 : 749-757.

Host-selective toxins produced by the plant pathogenic fungus Alternaria alternata (2012) T Tsuge, Y Harimoto, K Akimitsu, K Ohtani, M Kodama, Y Akagi, M Egusa, …, FEMS Microbiology Reviews 37: 44-66.

Molecular, ecological and evolutionary approaches to understanding Alternaria diseases of citrus (2003) K Akimitsu, TL Peever, LW Timmer, Molecular Plant Pathology 4: 435-446.

Sensitivity to Alternaria alternata toxin in citrus because of altered mitochondrial RNA processing (2002) K Ohtani, H Yamamoto, K Akimitsu, Proceedings of the National Academy of Sciences 99: 2439-2444.

The rare sugar D-allose acts as a triggering molecule of rice defence via ROS generation (2013) A Kano, T Fukumoto, K Ohtani, A Yoshihara, T Ohara, S Tajima, K Izumori, . K Akimitsu, Journal of Experimental Botany 64: 4939-4951.

このページの管理者:管理者


SDGs

飢餓をゼロにすべての人に健康と福祉を安全な水とトイレを世界中に産業と技術革新の基礎をつくろう海の豊かさを守ろう陸の豊かさも守ろう