Isolation and structural analysis of the Bx6 and Bx7 genes controlling the biosynthesis of benzoxazinoids in rye (Secale cereale L.)

Abstract

Benzoxazinoids (BXs) are plant secondary metabolites, first discovered in the 1950s, which are synthesized in many monocotyledonous species from the Poaceae family and in several dicotyledonous plants. They constitute a significant element of the plant's defence mechanism against both biotic (pests and diseases) and abiotic (elevated salinity, heavy metals) stresses. The aim of this research was to gain more information on the genetic background of BXs biosynthesis in rye (Secale cereale L.) by isolating and sequencing the ScBx6 L318 and ScBx7 L318 genes encoding 2-oxoglutarate-dependent dioxygenase and 7-O-methyltransferase, respectively. Using the modified Amplicon Express method, BAC clones containing the ScBx6 L318 and ScBx7 L318 genes were isolated and sequenced. The similarity between the ScBx6 L318 and ZmBx6 genes were, correspondingly, 78% and 68% in the coding sequence (cds) and the amino acid sequence (AA). A lesser similarity was found between the ScBx7 L318 and ZmBx7 genes (72% and 45% at the cds and AA levels, respectively).

The wheat dioxygenase BX6 is involved in the formation of benzoxazinoids in planta and contributes to plant defense against insect herbivores

“…Therefore, elucidating the BXD biosynthesis pathway in wheat is critical for improving the natural mode of defense against herbivores and to ensure food security. In the present study, TtBX6 from cultivated tetraploid wheat and TdBX6 from the wild emmer wheat were identified using sequence similarity to already known BX6 orthologs in maize (Zea mays) [58], rye (Secale cereale), and T. aestivum [27,59,60]. Sequence comparisons showed that S. cereale ScBX6 has a greater similarity with wheat BX6 paralogs [60] than with maize BX6 (Figure 2).…”

“…The gene IDs of BX6 genes in tetraploid and hexaploid wheat are listed in Supplementary Table S2. To identify further BX6 orthologs/paralogs, the well-characterized BX6 from maize [58] and ScBX6 from rye (Secale cereale) [59,60] were used to conduct a TBLASTN search against the genomes of hexaploid, tetraploid, and other Triticeae species, including T. urartu, a diploid progenitor of the bread wheat A subgenome, and Aegilops tauschii, a diploid progenitor of the bread wheat D subgenome [59]. The progenitor of the B subgenome is yet identified [61], therefore was not included in the analysis.…”

The wheat dioxygenase BX6 is involved in the formation of benzoxazinoids in planta and contributes to plant defense against insect herbivores

“…Therefore, elucidating the BXD biosynthesis pathway in wheat is critical for improving the natural mode of defense against herbivores and to ensure food security. In the present study, TtBX6 from cultivated tetraploid wheat and TdBX6 from the wild emmer wheat were identified using sequence similarity to already known BX6 orthologs in maize (Zea mays) [58], rye (Secale cereale), and T. aestivum [27,59,60]. Sequence comparisons showed that S. cereale ScBX6 has a greater similarity with wheat BX6 paralogs [60] than with maize BX6 (Figure 2).…”

“…In the present study, TtBX6 from cultivated tetraploid wheat and TdBX6 from the wild emmer wheat were identified using sequence similarity to already known BX6 orthologs in maize (Zea mays) [58], rye (Secale cereale), and T. aestivum [27,59,60]. Sequence comparisons showed that S. cereale ScBX6 has a greater similarity with wheat BX6 paralogs [60] than with maize BX6 (Figure 2). In hexaploid wheat, four TaBX6 genes were identified.…”

Genetic Resources of Cereal Crops for Aphid Resistance

“…For instance, various species of the Gramineae family with a relatively high concentration of BXDs are resistant to the greenbug [ 49 ]. It has been established by now that the synthesis of BXDs in maize is controlled by 16 genes ( ZmBx1 – ZmBx14 , ZmGlu1 – ZmGlu2 ) [ 50 , 51 ], by 13 in wheat ( TaBx1 – TaBx5 , TaGlu1a – TaGlu1d , TaGT1a – TaGT1d ) [ 52 , 53 ], and by eight ScBx genes in rye [ 54 ]. The plants of Hordeum brachyantherum Nevski, H. flexuosum (Nees ex Steud.)…”