Focusing on the root of a small flowering mustard plant, Arabidopsis thaliana, a research team led by Duke University biologist Philip Benfey created a detailed mosaic of cells showing where and when about 22,000 of the plant's roughly 28,000 genes are activated within growing root tissue.
The results, announced in the Dec. 12th issue of the journal Science, are the first to demonstrate "this level of resolution of gene expression on a global basis for any organism," said Benfey. The work, he said, serves as "a proof of principle" that similar approaches can be applied to other plant organs and other organisms.
It also marks the first time researchers have tracked the vast majority of an organism's genes as they are switched on and off as cells grow, continually divide and ultimately differentiate to build specialized tissue.
The ability to track gene expression on this scale (with each cellular division along a comprehensive front) is critical to answering one of biology's basic, yet most puzzling, processes: How do distinct, yet coordinated organs and specialized cells arise from the endless division of cells that initially seemed quite similar? For example, how does this complex process with a simple name, development, begin with a single, fertilized cell and ultimately yield a plant with roots, leaves, buds and blooms?
The researchers also found that different types of root cells tended to express particular sets of genes that were clustered together on the plant chromosomes. Understanding these patterns of cell types and gene clusters, Benfey said, could help biologists decipher the genetic machinery of development and eventually lead to new ways to enhance crops.