A research group of Ayaka Kinoshita, a third-year student at the University of Tokyo, has established an experimental method to identify the place where a gene works in a plant of the genus Monophilea, which grows one cotyledon indefinitely and spends a lifetime only on that leaf.We found that the genes that support cell division work in different places than normal plants.
In seed plants, the cells of the tissue continue to divide indefinitely and continue to form new organs (shoots) such as new leaves and stems, but the leaves can only grow to a fixed size after cell division stops for a certain period of time.However, a plant of the genus Monophilea of the Gesneriaceae family, called a monoleaf plant, does not form new organs until it blooms after germination and cotyledon emerges from the seed, and the cells of one cotyledon divide indefinitely. Then, the cotyledons continue to grow indefinitely.There are few experimental methods that can be applied to elucidate this mysterious growth pattern, and there have been few studies at the genetic level.
The research group investigated a method (whole mount in situ hybridization method) to clarify which cell the gene works on, and established the conditions applicable to monophilea.This method requires relatively little effort and can be observed while maintaining three-dimensional information.As a result, we discovered that genes that are key to cell division control work in a place different from normal plants, that is, in the tissue at the base of the cotyledon, which is considered to correspond to the shoot apical meristem.
This discovery not only contributes to the elucidation of the mechanism that supports the infinite growth of monophilea cotyledons and the characteristic of not forming new organs, but also continues to make shoots as to why the leaves of seed plants in general stop growing in the future. It is expected to help us to approach the mystery of whether we can do it.
