Expression of the abnormal gravitropism phenotypes creep and ageotropum during development in pea.

This study established that the mutant creep and ageotropum phenotypes are expressed differently during development in pea (Pisum sativum L.). Etiolated ageotropum stems grew at a wide range of angles, whereas etiolated creep stems emerged vertically from the compost. However, when etiolated creep stems were subjected to additional gravitropic demands, such as growth to excessive height or reorientation, abnormality was detectable. When plants were handled to a greater extent, earlier loss of vertical growth resulted. In light-grown shoots, creep lost vertical orientation, whereas ageotropum grew more normally. Root systems of creep exhibited normal growth patterns, whereas ageotropum main and lateral roots grew at abnormal angles. Thus, the ageotropum mutation strongly affects gravitropism in roots and etiolated stems, whereas the creep mutation affects both light- and dark-grown stems, but is most apparent in older, taller plants.