title: Nicotiana benthamiana calreticulin 3a is required for the ethylene-mediated production of phytoalexins and disease resistance against oomycete pathogen Phytophthora infestans.
abstract: Mature Nicotiana benthamiana shows strong resistance to the potato late blight pathogen Phytophthora infestans. By screening using virus-induced random gene silencing, we isolated a gene for plant-specific calreticulin NbCRT3a as a required gene for resistance of N. benthamiana against P. infestans. NbCRT3a encodes an endoplasmic reticulum quality-control (ERQC) chaperone for the maturation of glycoproteins, including glycosylated cell-surface receptors. NbCRT3a-silenced plants showed no detectable growth defects but resistance to P. infestans was significantly compromised. Defense responses induced by the treatment with INF1 (a secretory protein of P. infestans), such as production of reactive oxygen species and accumulation of phytoalexins, were suppressed in NbCRT3a-silenced N. benthamiana. Expression of an ethylene-regulated gene for phytoalexin biosynthesis, NbEAS, was reduced in NbCRT3a-silenced plants, whereas the expression of salicylic acid-regulated NbPR-1a was not affected. Consistently, induction of ethylene production by INF1 was suppressed in NbCRT3a-silenced plants. Resistance reactions induced by a hyphal wall components elicitor prepared from P. infestans were also impaired in NbCRT3a-silenced plants. However, cell death induced by active mitogen-activated protein kinase kinase (NbMEK2(DD)) was not affected by the silencing of NbCRT3a. Thus, NbCRT3a is required for the initiation of resistance reactions of N. benthamiana in response to elicitor molecules derived from P. infestans.
authors.affiliation: Nagoya University, Nagoya, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Matsukawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Shibata
authors.forename: Mina
authors.initials: M
authors.lastname: Ohtsu
authors.forename: Aki
authors.initials: A
authors.lastname: Mizutani
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mori
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Makoto
authors.initials: M
authors.lastname: Ojika
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Kawakita
authors.forename: Daigo
authors.initials: D
authors.lastname: Takemoto
mesh_terms: D000595:Amino Acid Sequence; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D020868:Gene Silencing; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010802:Phylogeny; D055750:Phytophthora infestans / Q000502:physiology*; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; D012717:Sesquiterpenes; C036216:ethylene; D000094162:Phytoalexins