Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

Both abscisic acid (ABA)‐dependent and ABA‐independent pathways govern the induction of NCED3, AAO3 and ABA1 in response to salt stress

Abstract: The responsiveness of plants to osmotic stress is critically mediated by the increase in abscisic acid (ABA) levels. Osmotic stress induces the biosynthesis of ABA, whose increased levels subsequently exert a positive feedback on its own biosynthetic pathway. As only qualitative or semi-quantitative analyses were performed to test the inducibility of ABA biosynthetic genes in Arabidopsis thaliana, we used quantitative reverse transcriptase-polymerase chain reaction to re-examine the induction of the ABA1, ABA2, ABA3, NCED3 and AAO3 genes by NaCl and ABA. Quantitative gene expression data obtained from wild-type plants and severely ABA-deficient mutants support the prevailing notion that the 9-cis-epoxycarotenoid cleavage reaction is the key regulatory step in NaCl-induced ABA biosynthesis. Interestingly, strong induction by NaCl of NCED3 was still observed in severe ABA-deficient mutants, pointing to an ABA-independent induction pathway for NCED3 that is NaCl-dependent. Therefore, in the absence of the ABA-mediated positive feedback on ABA biosynthesis, the ABA-independent pathway makes a major contribution to the induction of key ABA biosynthetic genes, such as NCED3, AAO3 and ABA1. In addition, and in contrast to some previous reports, our data do not support the limited ability of ABA to induce NCED3 expression. Under our experimental conditions, the induction of NCED3 by ABA, either in wild-type plants or ABA-deficient mutants, was predominant over that of other ABA biosynthetic genes. Natural variability was found in the induction by NaCl and ABA of NCED3 and ABA1 expression in different Arabidopsis accessions, although NCED3 expression was clearly predominant.

Volatile Compounds in Citrus Essential Oils: A Comprehensive Review

Abstract: The essential oil fraction obtained from the rind of Citrus spp. is rich in chemical compounds of interest for the food and perfume industries, and therefore has been extensively studied during the last decades. In this manuscript, we provide a comprehensive review of the volatile composition of this oil fraction and rind extracts for the 10 most studied Citrus species: C. sinensis (sweet orange), C. reticulata (mandarin), C. paradisi (grapefruit), C. grandis (pummelo), C. limon (lemon), C. medica (citron), C. aurantifolia (lime), C. aurantium (bitter orange), C. bergamia (bergamot orange), and C. junos (yuzu). Forty-nine volatile organic compounds have been reported in all 10 species, most of them terpenoid (90%), although about half of the volatile compounds identified in Citrus peel are non-terpenoid. Over 400 volatiles of different chemical nature have been exclusively described in only one of these species and some of them could be useful as species biomarkers. A hierarchical cluster analysis based on volatile composition arranges these Citrus species in three clusters which essentially mirrors those obtained with genetic information. The first cluster is comprised by C. reticulata, C. grandis, C. sinensis, C. paradisi and C. aurantium, and is mainly characterized by the presence of a larger abundance of non-terpenoid ester and aldehyde compounds than in the other species reviewed. The second cluster is comprised by C. junos, C. medica, C. aurantifolia, and C. bergamia, and is characterized by the prevalence of mono- and sesquiterpene hydrocarbons. Finally, C. limon shows a particular volatile profile with some sulfur monoterpenoids and non-terpenoid esters and aldehydes as part of its main differential peculiarities. A systematic description of the rind volatile composition in each of the species is provided together with a general comparison with those in leaves and blossoms. Additionally, the most widely used techniques for the extraction and analysis of volatile Citrus compounds are also described.