Plants have two classes of myosins. While recent work has focused on class XI myosins showing that myosin XI is responsible for organelle motility and cytoplasmic streaming, much less is known about the role of myosin...Plants have two classes of myosins. While recent work has focused on class XI myosins showing that myosin XI is responsible for organelle motility and cytoplasmic streaming, much less is known about the role of myosin VIII in plant growth and development. We have used a combination of RNAi and insertional knockouts to probe myosin VIII function in the moss Physcomitrella patens. We isolated Amyo8ABCDE plants demonstrating that myosin VIII is not required for plant viability. However, myosin VIII mutants are smaller than wild-type plants in part due to a defect in cell size. Additionally, Amyo8ABCDE plants produce more side branches and form gametophores much earlier than wild-type plants. In the ab- sence of nutrient media, Amyo8ABCDE plants exhibit significant protonemal patterning defects, including highly curved protonemal filaments, morphologically defective side branches, as well as an increase in the number of branches. Exogenous auxin partially rescues protonemal defects in Amyo8ABCDE plants grown in the absence of nutrients. This result, together with defects in protonemal branching, smaller caulonemal ceils, and accelerated development in the Amyo8ABCDE plants, suggests that myosin VIII is involved in hormone homeostasis in P patens.展开更多
文摘Plants have two classes of myosins. While recent work has focused on class XI myosins showing that myosin XI is responsible for organelle motility and cytoplasmic streaming, much less is known about the role of myosin VIII in plant growth and development. We have used a combination of RNAi and insertional knockouts to probe myosin VIII function in the moss Physcomitrella patens. We isolated Amyo8ABCDE plants demonstrating that myosin VIII is not required for plant viability. However, myosin VIII mutants are smaller than wild-type plants in part due to a defect in cell size. Additionally, Amyo8ABCDE plants produce more side branches and form gametophores much earlier than wild-type plants. In the ab- sence of nutrient media, Amyo8ABCDE plants exhibit significant protonemal patterning defects, including highly curved protonemal filaments, morphologically defective side branches, as well as an increase in the number of branches. Exogenous auxin partially rescues protonemal defects in Amyo8ABCDE plants grown in the absence of nutrients. This result, together with defects in protonemal branching, smaller caulonemal ceils, and accelerated development in the Amyo8ABCDE plants, suggests that myosin VIII is involved in hormone homeostasis in P patens.
