|Van Esbroeck, George|
|Holland, Jim - Jim|
Submitted to: Maydica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2008
Publication Date: 12/1/2008
Citation: Van Esbroeck, G., Ruiz, J., Sanchez, J., Holland, J.B. 2008. A COMPARISON OF LEAF APPEARANCE RATES AMONG TEOSINTE, MAIZE LANDRACES AND MODERN MAIZE. Maydica. 53:117-153. Interpretive Summary: A key component of plant development in grass species is the rate at which leaves are formed and emerge. The leaf development rate is important for determining the time to flowering of the plant. In some species, such as rice, this rate varies widely among different varieties. Previous Studies have shown that this rate varies in maize, but not greatly. We evaluated the most diverse sample yet of the genus Zea to test for variation in leaf development rate by including both a modern US hybrid, several Mexican landraces, and two wild teosinte relatives. We observed statistically significant variation for the leaf development rate, but it was small in magnitude, and more variation was observed within maize than between maize and teosinte. Therefore, this trait is not likely amenable to selection.
Technical Abstract: The rate at which successive new leaves emerge at the stem apex in gramineae (phyllochron) is largely controlled by temperature. Utilizing genetic variation for the phyllochron may be a way to alter plants’ responses to the environment or to manipulate time to maturity. Little is known about possible genetic variation in the phyllochron among maize landraces, its ancestor teosinte and modern maize. Controlled environment (phytotron) and field studies were conducted to investigate possible genetic variation for the phyllochron among seven maize (Zea mays) landraces (Apachito, Chapalote, Cónico, Tabloncillo, Tehua, Tuxpeño and, Zapalote Chico) sampled from the center of maize diversity in Mexico, a modern US maize hybrid (B73 x Mo17), and two teosintes (Zea diploperennis and Z. mays ssp. parviglumis). In the phytotron the phyllochron was determined for three day/night temperature regimes (22/18, 27/21 and 33/25 ºC) under a 12h photoperiod. Genetic variation for the phyllochron among the genotypes was observed in the phytotron and field, however, it was small with extreme values of about +/- 15% of the mean. A generally similar phyllochron for modern maize and its wild relatives suggested that this trait has been conserved despite thousands of years of human and natural selection. A similar leaf development rate among genotypes which varied widely for final leaf numbers (14-23) indicated that early flowering in some landraces was almost exclusively due to earlier floral initiation.