Plant Stem Cells Discovery

Plant Stem Cells Discovery

Although much of the focus and publicity on stem cell research is on animal cells, plants also have stem cells, which function similarly. Researchers at the Max Planck Society’s Institute for Developmental Biology in Germany have uncovered a feedback mechanism in plants which controls how many stem cells they have. A press release is available at the MPS site.

The parts of the plant which are above ground are generated by a tissue at the stop of the shoot called the “apical meristem,” which produces stem cells to make leaves, flowers, seeds, and yes, stems, throughout a plant’s life. Unlike animal stem cells, the stem cells produced by the apical meristem are capable of differentiating into any type of cell as long as the plant is growing. If the meristem produces too many stem cells, then there is uncontrolled growth, the plant equivalent of cancer; if too few, then the plant is stunted. The researchers wanted to find out how the plant regulated the number of its stem cells.

It was already known that growth hormones and a gene called WUSCHEL were involved, but it was unknown how the hormones and the gene worked together. The researchers found that the WUSCHEL gene restricts the activity of 4 other genes (ARRs) which “are part of a negative feedback loop, by which the growth-inducing plant hormone cytokinin limits its own influence.”

The hormone cytokinin is what causes the stem cells to multiply (by dividing), but it also activates the ARR genes, which then stop the cytokinin signaling and therefore stops growth. However, the WUSCHEL gene helps restrict the activity of the ARR genes, which means that more cytokinin can be produced. In other words, the WUSCHEL gene regulates how much growth hormone is produced by controlling the other genes that restrict it.

An earlier article about the discovery of the plant gene TCP20, which regulates cell growth and division, appeared on the BBC News site last September.

Understanding the role of growth hormones and cell division and regulation in plants can help give researchers understanding of similar processes in animals.

Cambridge University’s Plant Sciences Laboratory has some really cool pictures of plant cells. The images are copyrighted, so I will not reproduce them here, but poke around on their site if you are interested.