Systematic Comparisons of Orthologous Selenocysteine Methyltransferase and Homocysteine Methyltransferase Genes from Seven Monocots Species

De-Yong Zhao,Fu-Lai Sun,Long-Quan Yin,Zhi-Qiang Zhang,Bo Zhang

doi:10.15835/nsb.7.2.9491

Abstract

Identifying and manipulating genes underlying selenium metabolism could be helpful for increasing selenium content in crop grain, which is an important way to overcome diseases resulted from selenium deficiency. A reciprocal smallest distance algorithm (RSD) approach was applied using two experimentally confirmed Homocysteine S-Methyltransferases genes (HMT1 and HMT2) and a putative Selenocysteine Methyltransferase (SMT) from dicots plant Arabidopsis thaliana, to explore their orthologs in seven sequenced diploid monocot species: Oryza sativa, Zea mays, Sorghum bicolor, Brachypodium distachyon,Hordeum vulgare, Aegilops tauschii (the D-genome donor of common wheat) and Triticum urartu (the A-genome donor of common wheat). HMT1 was apparently diverged from HMT2 and most of SMT orthologs were the same with that of HMT2 in this study, leading to the hypothesis that SMT and HMT originate from one common ancestor gene. Identifying orthologs provide candidates for further experimental confirmation; also it could be helpful in designing primers to clone SMT or HMT orthologs in other crops.

Highlights

Selenium is an important micronutrient, essential for both humans and animals (Schwarz and Foltz, 1957; Schrauzer and Surai, 2009) as certain proteins require selenocysteine in their active site (Stadtman, 1990; 1996)
Comparison between rice, barley, maize, S. bicolor, B. distachyon, T. urartu and A. tauschii were conducted by the same method mentioned above, where query sequences were those which had been designated as Homocysteine SMethyltransferase (HMT) or Selenocysteine Methyltransferase (SMT) orthologs in the reciprocal Blastp between A. thaliana and each of these seven monocots
Different from the result of SMT, no HMT1 paralog was found in maize, rice, S. bicolor and B. distachyon

Summary

Introduction

Selenium is an important micronutrient, essential for both humans and animals (Schwarz and Foltz, 1957; Schrauzer and Surai, 2009) as certain proteins require selenocysteine in their active site (Stadtman, 1990; 1996). It is of great importance to increase selenium content in crops. Scientists have tried to increase grain selenium content through fertiliser-application fortification or breeding selenium-rich crop using the genotypic variation (Hawkesford et al, 2007; Lyons et al, 2005). There was little genotypic variation and much of the effects were associated with selenium spatial variation in soil (Lyons et al, 2005). Manipulating expression of genes underlying selenium metabolism through genetic modification could be a useful approach for increasing selenium content in crop grain. The prerequisite of genetic modification approach requires identifying the genes involved in selenium metabolism and clarifying their contributing roles to the final selenium content in plants

Methods

Results

Conclusion