Abstract
To investigate the dynamics of the potato – Potato virus Y (PVY) compatible interaction in relation to salicylic acid - controlled pathways we performed experiments using non-transgenic potato cv. Désirée, transgenic NahG-Désirée, cv. Igor and PVYNTN, the most aggressive strain of PVY. The importance of salicylic acid in viral multiplication and symptom development was confirmed by pronounced symptom development in NahG-Désirée, depleted in salicylic acid, and reversion of the effect after spraying with 2,6-dichloroisonicotinic acid (a salicylic acid - analogue). We have employed quantitative PCR for monitoring virus multiplication, as well as plant responses through expression of selected marker genes of photosynthetic activity, carbohydrate metabolism and the defence response. Viral multiplication was the slowest in inoculated potato of cv. Désirée, the only asymptomatic genotype in the study. The intensity of defence-related gene expression was much stronger in both sensitive genotypes (NahG-Désirée and cv. Igor) at the site of inoculation than in asymptomatic plants (cv. Désirée). Photosynthesis and carbohydrate metabolism gene expression differed between the symptomatic and asymptomatic phenotypes. The differential gene expression pattern of the two sensitive genotypes indicates that the outcome of the interaction does not rely simply on one regulatory component, but similar phenotypical features can result from distinct responses at the molecular level.
Highlights
Potato (Solanum tuberosum L.) is the world’s most widely grown tuber crop and the fourth largest food crop in terms of fresh produce after rice, wheat and corn
To investigate the role of salicylic acid (SA) in the potato-Potato virus Y (PVY) interaction, symptom development was monitored in genotypes differing in endogenous SA and sensitivity to virus (Table S1)
The molecular mechanisms that underlie host physiological and phenotypic responses to virus infection are still largely unknown, it has been shown that virus infection induces global activation or suppression of host gene expression [2,14,18,20, 24,25]
Summary
Potato (Solanum tuberosum L.) is the world’s most widely grown tuber crop and the fourth largest food crop in terms of fresh produce after rice, wheat and corn. PVYNTN elicits the development of potato tuber necrotic ringspot disease, causing a decrease in the quality and quantity of potato production. The ability of viruses to cause disease is determined by molecular interactions between the host plant and virus factors. These interactions directly affect virus replication and movement, symptom development and host defence responses [2]. Key signalling molecules in biotic interactions include salicylates, jasmonates and ethylene [3], but their specific roles depend on the particular host-pathogen interaction. SA plays an important role in compatible interactions, where the basal level of SA mediates expression of a cohort of defence-related genes inducing a defence-like response [6]. Methyl salicylate appears to be the major communication signal for defence both within and between plants [7,8]
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