Recently, Professor WAN Jian-min and his research team from the Institute of Crop Sciences of CAAS made a breakthrough in elucidating epigenetic mechanisms regulating plant height and flower organ development in rice. Their work has been accepted to publish in the world-leading journal, Plant Cell. The finding, as the first time in rice, demonstrates that DNA and histone methylation can have a profound effect on plant height and flower organ development, thus adding new evidence on important roles of epigenetic control in plant growth and development. This is their second paper published in this journal, following the publication on rice sterility in 2011.

WAN and his research group have been working in rice functional genomics for years, aiming to providing solutions in utilization of hybrid heterosis between japonica and indica rice. Heterosis between the two subspecies can lead to 10% to 30% yield increase over that within the subspecies. However，utilization of such heterosis is not easy because the hybrid plants are usually tall, partially sterile and late in flowering time. Researchers in this team isolated a dominant semi-dwarf mutant Epi-df, which has a strong capacity to lower the plant height and can be an alternative candidate to reduce height of F1 plants in japonica/indica hybrids. Epi-df encodes a histione modification factor FIE1. DNA hypo-methylation within promoter region of this gene resulted in its ectopic expression, causing dominant mild dwarfism along with partially aberrant flower organs.

“Epigenetics” refers to a phenomenon where changes in gene expression are heritable but are not associated with alterations in DNA sequence. It includes DNA methyaltion, histone modifications, chromatin remodeling, non-coding RNAs et al. Epigenetic regulation plays an important role in gene expression control, which has become a research hot field in recent years. A few spontaneous epigenetic mutants have been reported by far, such as clk, Epi-dwarf1, lcyc and Cnr, which are DNA hyper-methylated mutants. Arabidopsis fwa is the only DNA hypo-methylated mutant that has been found in plants. DNA hypo-methylated mutant has not been reported in grass plants, including important crops.