Constitutive expression of hrap gene in transgenic tobacco plant enhances resistance against virulent bacterial pathogens by induction of a hypersensitive response.
Hypersensitive response-assisting protein (HRAP) has been previously reported as an amphipathic plant protein isolated from sweet pepper that intensifies the harpin(Pss)-mediated hypersensitive response (HR). The hrap gene has no appreciable similarity to any other known sequences, and its activity can be rapidly induced by incompatible pathogen infection. To assess the function of the hrap gene in plant disease resistance, the CaMV 35S promoter was used to express sweet pepper hrap in transgenic tobacco. Compared with wild-type tobacco, transgenic tobacco plants exhibit more sensitivity to harpin(Pss) and show resistance to virulent pathogens (Pseudomonas syringae pv. tabaci and Erwinia carotovora subsp. carotovora). This disease resistance of transgenic tobacco does not originate from a constitutive HR, because endogenous level of salicylic acid and hsr203J mRNA showed similarities in transgenic and wildtype tobacco under noninfected conditions. However, following a virulent pathogen infection in hrap transgenic tobacco, hsr203J was rapidly induced and a micro-HR necrosis was visualized by trypan blue staining in the infiltration area. Consequently, we suggest that the disease resistance of transgenic plants may result from the induction of a HR by a virulent pathogen infection.
Ger
Mang-jye
MJ
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Chen
Cheng-Hsien
CH
Hwang
Shaw-Yhi
SY
Huang
Hsiang-En
HE
Podile
Appa Rao
AR
Dayakar
Badri Venkata
BV
Feng
Teng-yung
TY
D001483:Base Sequence; D017931:DNA Primers; D018744:DNA, Plant; D005822:Genetic Vectors; D016973:Pectobacterium carotovorum / Q000254:growth & development / Q000472:pathogenicity*; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics; D011549:Pseudomonas / Q000254:growth & development / Q000472:pathogenicity*; D020156:Salicylic Acid / Q000494:pharmacology; D014026:Nicotiana / Q000235:genetics* / Q000382:microbiology; D014774:Virulence / Q000235:genetics*
D017931:DNA Primers; D018744:DNA, Plant; D010940:Plant Proteins; C415122:hrap protein, Capsicum annuum; D020156:Salicylic Acid