StWRKY8 transcription factor regulates benzylisoquinoline alkaloid pathway in potato conferring resistance to late blight.
The resistance to late blight is either qualitative or quantitative in nature. Quantitative resistance is durable, but challenging due to polygenic inheritance. In the present study, the diploid potato genotypes resistant and susceptible to late blight, were profiled for metabolites. Tissue specific metabolite analysis of benzylisoquinoline alkaloids (BIAs) in response to pathogen infection revealed increased accumulation of morphinone, codeine-6-glucuronide and morphine-3-glucuronides. These BIAs are antimicrobial compounds and possibly involved in cell wall reinforcement, especially through cross-linking cell wall pectins. Quantitative reverse transcription-PCR studies revealed higher expressions of TyDC, NCS, COR-2 and StWRKY8 transcription factor genes, in resistant genotypes than in susceptible genotype, following pathogen inoculation. A luciferase transient expression assay confirmed the binding of the StWRKY8 TF to promoters of downstream genes, elucidating a direct regulatory role on BIAs biosynthetic genes. Sequence analysis of StWRKY8 in potato genotypes revealed polymorphism in the WRKY DNA binding domain in the susceptible genotype, which is important for the regulatory function of this gene. A complementation assay of StWRKY8 in Arabidopsis wrky33 mutant background was associated with decreased fungal biomass. In conclusion, StWRKY8 regulates the biosynthesis of BIAs that are both antimicrobial and reinforce cell walls to contain the pathogen to initial infection.
Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
Kalenahalli N
KN
Yogendra
Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
Dhananjay
D
Dhokane
Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada. Electronic address: ajjamada.kushalappa@mcgill.ca.
Ajjamada C
AC
Kushalappa
Departmento de Agronomia, Universidad National de Colombia, Bogota, Colombia.
Felipe
F
Sarmiento
Departmento de Agronomia, Universidad National de Colombia, Bogota, Colombia.
Ernesto
E
Rodriguez
Departmento de Agronomia, Universidad National de Colombia, Bogota, Colombia.
Teresa
T
Mosquera
D000595:Amino Acid Sequence; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000235:genetics; D044182:Benzylisoquinolines / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005838:Genotype; D010368:Pectins / Q000378:metabolism; D055750:Phytophthora infestans / Q000254:growth & development*; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011198:Solanum tuberosum / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; D044182:Benzylisoquinolines; D010940:Plant Proteins; D014157:Transcription Factors; C517860:WRKY33 protein, Arabidopsis; D010368:Pectins
Benzylisoquinoline alkaloids; Phytophthora infestans; Quantitative resistance; Solanum tuberosum; Transcription factors; Transcriptional regulation