LA JOLLA, CAThe first order of business for any fledgling plant embryo is to determine which end grows the shoot and which end puts down roots. Now, researchers at the Salk Institute expose the turf wars between two groups of antagonistic genetic master switches that set up a plant's polar axis with a root on one end and a shoot on the other.
"In what is arguably the most important decision for a plant, setting up the root/shoot axis, occurs during the early embryonic stages," says the study's lead author Jeffrey A. Long, Ph.D., an assistant professor in the Plant Molecular and Cellular Biology Laboratory. "A tightly controlled balancing act between two groups of transcriptions factors ensures that they stay where they belong and don't get into each other's way."
Plant embryogenesis establishes a very simple structure that contains two stem cell populations: the shoot meristem, which will give rise to all the "above-ground" organs such as the stem, the leaves and the flowers, and is the site of photosynthesis; and the root meristem, which gives rise to the root system, which lies below the ground and provides water and nutrients to the plant.
"Since plant stem cells ultimately give rise to all edible parts of plants understanding how their fate and function are regulated can be directly applied to modify the architecture of plants and to increase the yields of agriculturally important crops," says Long.
The Salk researchers' findings are published in the Feb. 28, 2010 advance online edition of the journal Nature.
"This work shows how genes interact in complex ways to establish organs along the root-shoot axis," said Susan Haynes, Ph.D., who oversees developmental biology grants at the NIH's National Institute of General Medical Sciences. "The study reveals important parallels with the gene networks that coordinate organ formation in animal embryos, and helps us understand the critical mechanisms that guide
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