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Cloning, expression, and sequence conservation of pathogenesis-related gene transcripts of potato
1Département de Biochimie, Université de Montréal, Québec, Canada.
Abstract:
Treatment of potato tuber disks with arachidonic acid elicits the accumulation of several mRNAs. cDNA clones corresponding to two of these mRNAs were isolated and characterized. Nucleotide sequence analysis reveals that both clones (pSTH-2 and pSTH-21) contain an open-reading frame coding for a 155-amino acid polypeptide. The polypeptides encoded by the two clones differ by only six amino acids and show a high degree of similarity with PR protein sequences from pea (approximately 42%) and parsley (approximately 37%). mRNAs corresponding to the two potato cDNA clones also accumulate in Solanum chacoense and in tomato following elicitor treatment. Maximum accumulation of the mRNAs corresponding to the two cDNA clones is reached 24 hr after elicitor treatment of the tuber disks. pSTH-2-related mRNAs also accumulate in tubers after wounding or treatment with eicosapentaenoic acid and are detected in potato and tomato leaves treated with a Phytophthora infestans mycelium homogenate. The presence of these conserved genes in species from three plant families and the similarity of their induction pattern suggest an important function during the plant defense response.
Insights
Plant defense genes are activated by arachidonic acid. These genes, identified in potato (Solanum tuberosum), are conserved across plant families, indicating a crucial role in plant immunity.
Area of Science:
- Plant Molecular Biology
- Plant Pathology
- Biochemistry
Background:
- Plant defense responses are crucial for survival against pathogens.
- Elicitors, such as arachidonic acid, can trigger defense mechanisms in plants.
- Messenger RNAs (mRNAs) play a key role in gene expression during these responses.
Purpose of the Study:
- To identify and characterize novel genes involved in the plant defense response.
- To investigate the role of arachidonic acid in inducing defense-related gene expression in potato.
- To explore the conservation and induction patterns of these genes in different plant species.
Main Methods:
- Treatment of potato tuber disks with arachidonic acid.
- Isolation and characterization of complementary DNA (cDNA) clones (pSTH-2 and pSTH-21).
- Nucleotide sequence analysis to determine polypeptide sequences and similarities.
- Analysis of mRNA accumulation in response to various treatments and in different plant tissues/species.
Main Results:
- Two cDNA clones, pSTH-2 and pSTH-21, were isolated, each encoding a 155-amino acid polypeptide.
- The encoded polypeptides showed significant similarity to known pathogenesis-related (PR) proteins.
- Induced mRNAs accumulated in potato, Solanum chacoense, and tomato after elicitor treatment, with maximum levels at 24 hours.
- Similar mRNAs were also found in response to wounding, eicosapentaenoic acid, and Phytophthora infestans treatment.
Conclusions:
- The identified genes are conserved across plant families, suggesting a fundamental role in plant defense.
- The induction patterns indicate these genes are important components of the plant's immune system.
- These findings contribute to understanding the molecular mechanisms underlying plant-pathogen interactions.