Differential Triggering of the Phenylpropanoid Biosynthetic Pathway Key Genes Transcription upon Cold Stress and Viral Infection in Tomato Leaves

Polyxeni Pappi,Nikolaos Nikoloudakis,Dimitrios Fanourakis,Antonios Zambounis,Georgios Tsaniklidis,Costas Delis

doi:10.3390/horticulturae7110448

Abstract

Plants develop a plethora of defense strategies during their acclimation and interactions with various environmental stresses. Secondary metabolites play a pivotal role in the processes during stress acclimation, therefore deciphering their relevant responses exchange the interpretation of the underlying molecular mechanisms that may contribute to improved adaptability and efficacy. In the current study, tomato plants were exposed to short-term cold stress (5 °C for 16 h) or inoculated (20 d) with either Cucumber Mosaic Virus (CMV) or Potato Virus Y (PVY). Responses were recorded via the assessments of leaf total phenolic (TP) content, total flavonoid (TF) levels, and phenylalanine ammonia-lyase (PAL) enzyme activity. The transcription of the gene families regulating the core phenylpropanoid biosynthetic pathway (PBP) at an early (PAL, cinnamic acid 4-hydroxylase, 4-coumarate-CoA ligase) or late (chalcone synthase and flavonol synthase) stage was also evaluated. The results showed that cold stress stimulated an increase in TP and TF contents, while PAL enzyme activity was also elevated compared to viral infection. Besides genes transcription of the enzymes involved in the core PBP was mostly induced by cold stress, whereas transcription of the genes regulating flavonoid biosynthesis was mainly triggered by viral infection. In conclusion, abiotic and biotic stressors induced differential regulation of the core PBP and flavonoid biosynthetic metabolism. Taking the above into consideration, our results highlight the complexity of tomato responses to diverse stimuli allowing for better elucidation of stress tolerance mechanisms at this crop.

Highlights

In planta, L-phenylalanine serves as the biosynthesis precursor of a range of secondary metabolites, which are centrally involved in fundamental physiological and
Combined biotic (CMV or potato virus Y (PVY)) and abiotic stress induced an increase in leaf total phenolic (TP)
Data of this study indicate that cold stress generally upregulated the transcription of either binding to the capsid proteins or direct inhibition of the viral polymerases, most genes related to the core phenylpropanoid biosynthetic pathway (PBP), as well as genes participating in the flavonoid obstructing the viral infection [37]

Summary

Introduction

L-phenylalanine serves as the biosynthesis precursor of a range of secondary metabolites, which are centrally involved in fundamental physiological and. L-phenylalanine as the are biosynthesis of abiosynthetic range of secondary via the phenylpropanoid biosynthetic pathway (PBP; [1]) Regardless of their structural metabolites, which are centrally involved in fundamental physiological and developmental differences and physiological all PBP products share the first three conversion steps processes. These metabolites roles, are regulated by complex biosynthetic routes via the phenyl(termed general. At three the interface between primary and physiological roles, all PBP products share theisfirst conversion steps It is the initial and rate limiting

Objectives

Methods

Results