Location: Corn Insects and Crop Genetics ResearchTitle: Multicellular Secretory Trichome Development on Soybean and Related Glycine Gynoecia Author
Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2009
Publication Date: 4/28/2009
Citation: Healy, R.A., Palmer, R.G., Horner, H.T. 2009. Multicellular Secretory Trichome Development on Soybean and Related Glycine Gynoecia. International Journal of Plant Science. 170(4):444-456. Interpretive Summary: Hairs or trichomes on plants have many functions. This includes mechanical protection of the female organs from insect or wind damage, production of substances that deter herbivores, attraction of pollinators and/or inhibition of microbes. In soybean, we noticed different types of trichomes on the female organs and at the base of the female organs. Our objective was to study the multicellular secretory trichomes using light and electron microscopy with histochemistry. These specialized trichomes form about two days before flowering. These trichomes are very active metabolically forming carbohydrate/protein products. Products are secreted internally and then excided outside the cell. Composition and function of the products are not known. Once the identity of these secretory products are known, the function(s) can be determined. We anticipate this will help us to select parent lines to use in hybrid soybean seed production. Hybrid soybean will increase yields and contribute to increased farm income.
Technical Abstract: Multicellular glandular trichomes form on gynoecia of wild Glycine annual species, annual soybean cultivars, and wild perennial species. These trichomes occur on gynoecia of annual taxa from ovary base to style base, and along style of perennial species. Trichomes form at least two days prior to anthesis, and new trichomes develop throughout flowering, including young seed pods. Trichome structure is similar in all taxa examined, usually five to seven linearly-arranged cells. Stalk cells with callose walls become highly vacuolate, and their cytoplasm have reduced numbers of Golgi bodies and endoplasmic reticulum. During secretion, two to four distal cells develop dense cytoplasm with prominent Golgi bodies with large vesicles, and endoplasmic reticulum with enlarged lumens. Both organelles are involved in forming carbohydrate/protein secretory products. Internal secretion begins with products exuding between plasmalemma and primary wall of each distal cell. Secretion progresses between primary wall and the outermost cuticle that entirely covers the trichome, which is thicker and more highly modified than normal cuticle. It separates from cell walls in secretion regions. Products are exuded outside, and are visible along inner surface of trichome and gynoecium, and more obvious in perennial than in annual taxa. Composition and function of products are unknown.