R2R3-Myb genes constitute one of the largest families of regulatory proteins in plants. In the grasses, a group of these genes underwent amplification about 50 million years ago and is characterized by a change of proline to alanine in the hinge region between R2 and R3 and hence called as P-to-A clade. R2R3 Myb P-to-A genes comprise about 10 members, including well-characterized maize P1 regulator of phlobaphene biosynthesis. ZmMyb-IF35, one of the R2R3 Myb P-to-A genes, shares a common ancestor with P1, and appears to control the accumulation of phenylpropanoid compounds related to those controlled by P1, but is unlikely to participate in the control of flavonoid accumulation.
To understand the duplication and divergence of regulatory genes, we have focused on the functional characterization of the recently duplicated ZmMyb-IF35 and ZmMyb-IF25 genes from maize, and their ortholog in rice, OsMyb-IF.
Expression studies in Zea mays (B73) using RT-PCR indicate that ZmMyb-IF35 expresses throughout the plant body at low levels. However, in situ hybridization studies showed the expression to be restricted to the vascular tissues. In contrast, OsMYB-IF in Oryza sativa (cv. Nipponbare) is well expressed in leaves and callus tissue and in situ studies indicate mRNA presence in all tissues types observed including the epidermis, mesophyll and vascular cells.
We are using both gain of function and loss of function approaches in maize and rice to establish the function of these genes. Metabolic profiling using HPLC and GC-MS of over-expression and knockout lines is in progress.
back to projects summary
