The most prevalent current hypothesis is that the cytoskeleton, or cellular scaffolding, plays a major role in this gravity-sensing, intercellular communication; the cytoskeleton is made up of filaments, consisting of the proteins actin or tubulin, that allow movement of materials along strands, such as is seen in meiosis or mitosis. However, there is a major controversy in the field regarding the role of actin in gravitropism primarily due to contradictory outcomes in studies where actin was inhibitedthe most interesting ones, according to Blancaflor, being those where actin disruption actually led to enhanced gravitropism.
Blancaflor tackles this controversy by reviewing what we know regarding how amyloplasts work, what affects actin, and how recent genetic studies have discovered that proteins may regulate actin and therefore auxin distribution. For example, recent genetic work using the model plant, Arabidopsis, reveals potential mechanisms as to how the actin cytoskeleton connects the gravity sensing cells to auxin in the growing cells.
Although Blancaflor's review article specifically discusses, based on years of research, how one component of the plant cell, namely the cytoskeleton, controls the process of plant gravitropism, he notes that understanding gravitropism has important implications for agricultu
|Contact: Richard Hund|
American Journal of Botany