AUTHOR=Ruiz-Hernández Victoria , Hermans Benjamin , Weiss Julia , Egea-Cortines Marcos 

TITLE=Genetic Analysis of Natural Variation in Antirrhinum Scent Profiles Identifies BENZOIC ACID CARBOXYMETHYL TRANSFERASE As the Major Locus Controlling Methyl Benzoate Synthesis

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00027

DOI=10.3389/fpls.2017.00027

ISSN=1664-462X

ABSTRACT=<p>The <italic>Antirrhinum</italic> genus has a considerable complexity in the scent profiles produced by different species. We have analyzed the genetic differences between <italic>A. majus</italic> and <italic>A. linkianum</italic>, two species divergent in the emission of methyl benzoate, methyl cinnamate, acetophenone, and ocimene. The genetic analysis showed that all compounds segregated in a Mendelian fashion attributable to one or two <italic>loci</italic> with simple or epistatic interactions. Several lines lacked methyl benzoate, a major Volatile Organic Compound emitted by <italic>A. majus</italic> but missing in <italic>A. linkianum</italic>. Using a candidate gene approach, we found that the <italic>BENZOIC ACID CARBOXYMETHYL TRANSFERASE</italic> from <italic>A. linkianum</italic> appeared to be a null allele as we could not detect mRNA expression. The coding region did not show significant differences that could explain the loss of expression. The intron-exon boundaries was also conserved indicating that there is no alternative splicing in <italic>A. linkianum</italic> as compared to <italic>A. majus</italic>. However, it showed multiple polymorphisms in the 5′ promoter region including two insertions, one harboring an <italic>IDLE</italic> MITE transposon with additional sequences with high homology to the <italic>PLENA locus</italic> and a second one with somewhat lower homology to the regulatory region of the <italic>VENOSA locus</italic>. It also had a 778 bp deletion as compared to the <italic>A. majus BAMT</italic> promoter region. Our results show that the differences in scent emission between <italic>A. majus</italic> and <italic>A. linkianum</italic> may be traced back to single genes involved in discrete biosynthetic reactions such as benzoic acid methylation. Thus, natural variation of this complex trait maybe the result of combinations of wild type, and loss of function alleles in different genes involved in discrete VOCs biosynthesis. Furthermore, the presence of active transposable elements in the genus may account for rapid evolution and instability, raising the possibility of adaptation to local pollinators.</p>