Structural characteristics of ScBx genes controlling the biosynthesis of hydroxamic acids in rye (Secale cereale L.)

Abstract

Benzoxazinoids (BX) are major secondary metabolites of gramineous plants that play an important role in disease resistance and allelopathy. They also have many other unique properties including anti-bacterial and anti-fungal activity, and the ability to reduce alfa–amylase activity. The biosynthesis and modification of BX are controlled by the genes Bx1 ÷ Bx10, GT and glu, and the majority of these Bx genes have been mapped in maize, wheat and rye. However, the genetic basis of BX biosynthesis remains largely uncharacterized apart from some data from maize and wheat. The aim of this study was to isolate, sequence and characterize five genes (ScBx1, ScBx2, ScBx3, ScBx4 and ScBx5) encoding enzymes involved in the synthesis of DIBOA, an important defense compound of rye. Using a modified 3D procedure of BAC library screening, seven BAC clones containing all of the ScBx genes were isolated and sequenced. Bioinformatic analyses of the resulting contigs were used to examine the structure and other features of these genes, including their promoters, introns and 3’UTRs. Comparative analysis showed that the ScBx genes are similar to those of other Poaceae species, especially to the TaBx genes. The polymorphisms present both in the coding sequences and non-coding regions of ScBx in relation to other Bx genes are predicted to have an impact on the expression, structure and properties of the encoded proteins.Electronic supplementary materialThe online version of this article (doi:10.1007/s13353-015-0271-z) contains supplementary material, which is available to authorized users.

Cross-talk of the biotrophic pathogen Claviceps purpurea and its host Secale cereale

“…In Δcptf1 a gene encoding an enzyme involved in the biosynthesis of hydroxamic acids in rye is induced. These compounds have been shown to have anti-fungal activity and to play an important role in disease resistance [26, 27]. Furthermore, the expression of a gene with high homology to an inhibitor for fungal xylanases (Sc4Loc00580338.2) as well as a predicted disease resistance protein (Sc4Loc01458017.2) is significantly induced solely in Δcptf1 infected ovaries.…”

ScBx gene based association analysis of hydroxamate content in rye (Secale cereale L.)

“…In the analysis, the sequences of ScBx1 ÷ ScBx5 genes (Table 2) previously sequenced and characterized in rye inbred line L318 by Bakera et al (2015) were used. The analysed sequences comprised exons, introns, 3′-UTRs and promoters (except for ScBx1 in which no 3′-UTRs were assayed).…”

“…The present study concerns an association analysis based on sequences of five candidate genes: ScBx1 – ScBx5 . These genes, recently sequenced and characterized by Bakera et al (2015), control the first five reactions in HX biosynthesis: from the conversion of indole-3-glycerolphosphate to indole followed by four monooxidations with the final product 2,4-dihydroxy-1,4-benzoxazin-3-one.…”

“…Twenty-eight polymorphisms of Bx1 and one polymorphism of Bx2 were significantly associated with the content of DIMBOA and DIMBOA-Glc in leaves. Bakera et al (2015) showed that rye ScBx genes present in different rye accessions were generaly similar at the nucleotide level, but a few SNPs and INDELs were found. The highest number of SNPs was identified in the first exon of ScBx2 , with A/G, C/T and T/C being the most frequent polymorphisms.…”

The genetic background of benzoxazinoid biosynthesis in cereals

“…Orthologs of the maize genes Bx1-Bx5 have also been identified in hexaploid Triticum aestivum (Nomura et al 2002(Nomura et al , 2003, diploid wheat Triticum boeoticum (Nomura et al 2007), Secale cereale (Rakoczy-Trojanowska et al 2013; Bakera et al 2015) and Hordeum lechleri (Grün et al 2005). Genes encoding glucosylglucosidases (Taglu1a, Taglu1b, Taglu1c, Taglu1d, Scglu) and glucosyltransferases (TaGTa, TaGTb, TaGTc, TaGTd, ScGT) have been identified in hexaploid wheat (Sue et al 2006) and rye (Nikus et al 2003;Sue et al 2011).…”