Monoterpene Synthase Genes and Monoterpene Profiles in Pinus nigra subsp. laricio.

Enrica Alicandri,Maurizio Badiani,Anna Rita Paolacci,Stefano Covino,Agostino Sorgonà,Bartolomeo Sebastiani,Mario Ciaffi

doi:10.3390/plants11030449

Abstract

In the present study, we carried out a quantitative analysis of the monoterpenes composition in different tissues of the non-model conifer Pinus nigra J.F. Arnold subsp. laricio Palib. ex Maire (P. laricio, in short). All the P. laricio tissues examined showed the presence of the same fourteen monoterpenes, among which the most abundant were β-phellandrene, α-pinene, and β-pinene, whose distribution was markedly tissue-specific. In parallel, from the same plant tissues, we isolated seven full-length cDNA transcripts coding for as many monoterpene synthases, each of which was found to be attributable to one of the seven phylogenetic groups in which the d1-clade of the canonical classification of plants’ terpene synthases can be subdivided. The amino acid sequences deduced from the above cDNA transcripts allowed to predict their putative involvement in the biosynthesis of five of the monoterpenes identified. Transcripts profiling revealed a differential gene expression across the different tissues examined, and was found to be consistent with the corresponding metabolites profiles. The genomic organization of the seven isolated monoterpene synthase genes was also determined.

Highlights

In addition, here, we report about the isolation of full-length (FL) cDNAs and the corresponding genomic sequences encoding for six monoterpene synthases (MTPSs) and one hemi-terpene synthases (TPSs), obtained by using a strategy based on the phylogeny of available MTPSs from different Pinus species
The diversity of the monoterpene composition was evaluated in five different tissues, namely, young (YN) and mature (MN) needles, leader and interwhorl stems (LS and IS, respectively), and roots (R), obtained from three-year-old P. laricio saplings
As a matter of fact, in a previous study of ours conducted on adult individuals of P. laricio thriving in the same natural context of the present study [27], we adopted the “headspace” gas chromatography–mass spectrometry (GC–MS) approach to collect volatile terpenoids emitted from vegetation, and we found that, together with a ten of different sesquiterpenes, at least half of the same monoterpenes reported in Figure 1, namely, bornyl acetate, limonene, myrcene, β-phellandrene, α- and β-pinene, and α-terpineol, were persistently and consistently present in the blend of volatiles released by the young needles throughout their growing season, with β-phellandrene and α- and β-pinene being the major components on a comparative basis

Summary

Introduction

The production of terpenoids in conifer species, both in the form of oleoresin and emitted as volatile compounds, plays a significant role in the physical and chemical defence responses against herbivores and pathogens [5,6]. Conifer foliage emits terpenes originating from two sources: those stored in the needle resin ducts and those directly emitted from mesophyll cells [5] These volatile terpenes, mainly mono- and sesquiterpenes, can play a significant role in plant-to-environment interactions, acting as signals to stimulate defence responses in nearby plants or in healthy tissues of the same plant or in attracting natural enemies of pathogens and herbivores [5,8,9]

Methods

Results

Conclusion