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Scientists identify gene that regulates architecture of plant cells
By Birgit Reinert


Plant biologists have identified a gene that appears to regulate the growth and development of plant cells. The researchers cloned a gene known as SPK1 in the mustard weed Arabidopsis thaliana and compared the mutant plant to a normal Arabidopsis plant. In the mutant plants, the shape and architecture of cells and tissue were severely altered and stunted. A better understanding of how the SPK1 gene controls plant growth and development could help scientists grow plants with higher crop yields.

The plant on the left is a normal, one-week-old Arabidopsis seedling. The seedling on the right is of the same age but contains a mutant gene that has caused smaller misshapen leaves.

"Ultimately things like organ shape and whole plant architecture are really important for crop yield in the field," Daniel Szymanski, a molecular biologist of Purdue University in West Lafayette, Indiana, is quoted as saying. "The angle of the leaves defines how tightly you can pack plants in when you plant them. Root architecture controls the ability of plants to take up nutrients."

Szymanski and colleagues identified the SPK1 gene using a genetic screen based on the shape of trichomes, the hair-like structures present on the surface of many plants. Trichomes are thought to protect plants from insects by limiting access to the plant tissue. Studying the trichomes on the Arabidopsis leaves, the researchers found that the mutant plants had leaf trichomes with aborted or two branches compared with three branches of normal trichomes. The trichomes of the plants with the mutant SPK1 gene "were highly elongated, unbranched, and often abnormally swollen or blebbed at various positions along the stalk," the researchers write in The Plant Cell.

Other defects in the mutant plant were found in the shape of the leaves and the development of cotyledons, the seed leaves within the embryo of a seed.

The study suggests that the SPK1 gene is involved in the plant's organization of the cytoskeleton—the internal structure of the cell. "Our long-term goal is to understand how the organization of the cytoskeleton is regulated and its function during epidermal cell and tissue morphogenesis," the researchers write.

For more images, see related Art Gallery Genes and plant architecture.

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Qiu, J.-L. et al. The Arabidopsis SPIKE1 gene is required for normal cell shape control and tissue development. Plant Cell 14, 101-118 (January 2002).

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