Deng Xingwang

The MYB transcription factor superfamily of Arabidopsis : expression analysis and phylogenetic comparison with the rice MYB family

MYB proteins are a superfamily of transcription factors that play regulatory roles in developmental processes and defense responses in plants. We identified 198 genes in the MYB superfamily from an analysis of the complete Arabidopsis genome sequence, among them, 126 are R2R3-MYB, 5 are R1R2R3-MYB, 64 are MYB-related, and 3 atypical MYB genes. Here we report the expression profiles of 163 genes in the Arabidopsis MYB superfamily whose full-length open reading frames have been isolated. This analysis indicated that the expression for most of the Arabidopsis MYB genes were responsive to one or multiple types of hormone and stress treatments. A phylogenetic comparison of the members of this superfamily in Arabidopsis and rice suggested that the Arabidopsis MYB superfamily underwent a rapid expansion after its divergence from monocots but before its divergence from other dicots. It is likely that the MYB-related family was more ancient than the R2R3-MYB gene family, or had evolved more rapidly. Therefore, the MYB gene superfamily represents an excellent system for investigating the evolution of large and complex gene families in higher plants. Our comprehensive analysis of this largest transcription factor superfamily of Arabidopsis and rice may help elucidate the possible biological roles of the MYB genes in various aspects of flowering plants.

Hybrid Rice Breeding Welcomes a New Era of Molecular Crop Design

Heterosis, or hybrid vigor, is a general phenomenon in biology. Harvest of heterosis has been succeeded in a number of crop species. Hybrid rice was first adapted in China in large scale in the middle of 1970s, and two generations of hybrid seed production technology based on distinct male sterility mutations have been employed. New hybrid seed production systems have been reported lately using the modern biotechnology and molecular crop design, which may lead to a new era of hybrid rice practice.

Allelic DNA Methylation Analysis in Arabidopsis Hybrids Associated with siRNA

Recently, accumulating evidence suggests that epigenetic factors including DNA methylation, small RNA and histone modifications may play important roles in hybrid vigor in plants. However, knowledge about the mechanism of these epigenetic factors in hybrids is still limited. Based on genome-wide DNA methylation and small RNA maps of Arabidopsis thaliana Ler and C24 ecotypes and their reciprocal F 1 hybrids in previous work, we further analyzed allelic specific DNA methylation. Our study indicated that both trans - and cis -factors play roles in DNA methylation regulations in hybrids. In addition, we found that siRNAs correlate with DNA methylation trans -regulations. High degree trans -regulation DNA methylation is significantly concurrent with enriched siRNA regions. Our study analyzed DNA methylation regulations associated with siRNAs in hybrids, and shed light on understanding the mechanism of hybrid vigor.