Genetic, Environmental, and Physiological Control of Leaf Orientation in Plantago Lanceolata

Abstract

Considerable diversity in genes controlling leaf orientation in P. lanceolata has been demonstrated in a population growing in the Sydney area. The expression of these genes is greatly influenced by both light intensity and temperature; low light intensity and high temperature induces erect leaf orientation, while conversely high light intensity and low temperature favours the formation of prostrate leaves. Gibberellin apparently blocks the expression of the genes for prostrate leaf orientation. It is suggested that the seasonal variation in air temperature may be the climatic factor chiefly responsible for the disappearance of prostrate leaf orientation in midsummer and for the reappearance of this character in autumn and winter.