Submitted to: Genes and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/1996
Publication Date: N/A
Interpretive Summary: Insect pests, disease organisms, and environmental pollutants destroy millions of dollars of crops in the U.S. every year. To damage plants, these attackers must penetrate the outermost layer of cells called the epidermis. A major goal of genetic engineering is to strengthen the leaf epidermis, the plant's first line of defense. A genetic master switch has been discovered that controls several leaf epidermal traits in corn. This "master switch", known as the Glossy15 gene, controls the presence of waxes and leaf hairs on the surface of corn leaves and affects leaf cell chemistry. This paper reports the cloning and sequencing of this important gene. The ability to modify the Glossy15 gene will allow genetic engineers to make corn and other plants more resistant to pests, pathogens, ultra- violet light, and perhaps even drought. Because it is also demostrated that a similar gene exists in sorghum, other grasses, and perhaps even dicots such as soybeans, the impact of this research may reach far beyond maize.
Technical Abstract: Vegetative development in many plants is characterized by the production of distinct juvenile and adult leaves, which in maize differ by the alternate expression of a variety of epidermal cell traits. These include leaf waxes, leaf hairs, and changes in epidermal cell wall morphology and biochemistry. The maize Glossy15 (Gl15) gene is required for a juvenile instead of adult leaf epidermal cell identity beyond the second leaf. The Gl15 gene was cloned using a defective Suppressor- Mutator (dSpm) element insertion as a transposon-tag. Like the Gl15 mutant phenotype, Gl15 mRNA expression was observed only in juvenile leaves beyond leaf two, indicating that Gl15 acts as a homeotic regulator of maize leaf identity. The Gl15 gene encodes a putative transcription factor with significant sequence similarity to the DNA-binding domains from the Arabidopsis regulatory genes APETALA2 and AINTEGUMENTA. This finding expands the known functions of AP2-related genes to include the control of both vegetative and reproductive lateral organ identity, and provides molecular support for the hypothesis that leaves and floral organs are related structures derived from a common growth plan.