Abstract

Recently, Xylella fastidiosa was reported in Italy, associated with the "Olive Quick Decline Syndrome". The cv. Leccino exhibits an evident tolerance with a slow disease progression compared with the other cultivars. Between the mechanisms proposed to explain the putative tolerance of some hosts to X. fastidiosa diseases, lignin deposition plays an important role. Analysis of phenolic compounds in healthy and infected Leccino and Cellina di Nardò leaves showed, in the two cultivars, a reduction of hydroxytyrosol glucoside (usually associated with drought and cold stress) and, only in Leccino, an increase of quinic acid, precursor of lignin. To determine if lignin biosynthesis is involved in defence response, we investigated the expression of genes coding for entry-point enzymes in different branches of the phenylpropanoid pathway. In stems of Cellina di Nardò infected plants, Cinnamate-4-Hydroxylase (C4H) and 4-Coumarate:CoA Ligase (4CL) resulted strongly down-regulated, indicating a plant disease response since the inhibition of C4H is reported to promote the accumulation of benzoic acid and salicylic acid as defence signals. Instead, in the cv. Leccino, Cinnamoyl-CoA Reductase (CCR, reported to be strongly induced during the formation of lignin defence response associated) was up-regulated in the stem of infected plants; moreover, Polyphenol oxidase (PPO), coding for an enzyme involved in the hydroxytyrosol biosynthesis, was down-regulated. The quantification of lignin in healthy and infected branches of both cultivars, showed a significant increase of total lignin in infected Leccino compared with the sensitive cultivar; moreover, histochemical observations of stem sections exhibited a different lignin distribution in the sclerenchyma and in the xylem tissue of infected Leccino plants compared to sections of healthy ones. Results suggest a critical role for lignin in X. fastidiosa tolerance of cv. Leccino.

Autore Pugliese

• De Bellis Luigi , Aprile Alessio , Miceli Antonio , Luvisi Andrea

Tutti gli autori

• Sabella E. , Luvisi A. , Aprile A. , Negro C. , Vergine M. , Nicoli F. , Miceli A. , De Bellis L.

Titolo volume/Rivista

JOURNAL OF PLANT PHYSIOLOGY

Anno di pubblicazione

2018

ISSN

0176-1617

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

1

Ultimo Aggiornamento Citazioni

22/04/2018

Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile