Structure and evolutionary relationships among paralogous genes within the Sec2 locus in rye |
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Authors: | Yanqian Wang Bo Zhang Baolong Liu Huaigang Zhang Dengcai Liu |
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Affiliation: | 1. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, PR China;2. Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, Chengdu 611130, Sichuan, PR China;3. Graduate University, Chinese Academy of Sciences, Beijing 100049, PR China |
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Abstract: | The 75K γ-secalins encoded by genes present at the locus Sec2 on chromosome 2R are unique to rye and contribute about half of all rye storage proteins. However, there is a lack of sequence information for paralogous genes in this locus. For this study, 59 γ-secalin paralogous sequences in the Sec2 locus were characterized from a cultivated rye and derived lines after crossing with bread wheat. They had similar structures with conserved sequences in their repetitive regions for the signal peptide, N-terminal, C-terminal and the repeat motif. Their high homology indicated that they originated from an ancestor sequence that existed before the speciation of the genus Secale. Duplication and divergence might have led to the formation of the paralogous genes at Sec2. Besides point mutations, these paralogs showed variations in DNA length due to insertion or deletion events in their repetitive regions. They encoded secalins with deduced molecular weight ranges between 22.2 and 54.5 kDa. These insertion or deletions may be caused by illegitimate recombination and this locus seemed to contribute to increased levels of protein content. However, the incorporation of locus Sec2 may have a negative effect on flour processing quality since it reduced the SDS-sedimentation value. |
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Keywords: | Rye Sec2 Secalin Seed storage protein |
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