Lu Y T, Feldman L J
Department of Plant Biology, University of California, Berkeley 94720-3102, USA.
Planta. 1997;203 Suppl:S91-7. doi: 10.1007/pl00008121.
Roots of many species grow downward (orthogravitropism) only when illuminated. Previous work suggests that this is a calcium-regulated response and that both calmodulin and calcium/calmodulin-dependent kinases participate in transducing gravity and light stimuli. A genomic sequence has been obtained for a calcium/calmodulin-dependent kinase homolog (MCK1) expressed in root caps, the site of perception for both light and gravity. This homolog consists of 7265 base pairs and contains 11 exons and 10 introns. Since MCK1 is expressed constitutively in both light and dark, it is unlikely that the light directly affects MCK1 expression, though the activity of the protein may be affected by light. In cultivars showing light-regulated gravitropism, we hypothesize that MCK1, or a homolog, functions in establishing the auxin asymmetry necessary for orthogravitropism.
许多物种的根只有在光照下才向下生长（正向重力性）。先前的研究表明，这是一种钙调节反应，钙调蛋白和钙/钙调蛋白依赖性激酶都参与重力和光刺激的转导。已获得在根冠（光和重力的感知部位）中表达的钙/钙调蛋白依赖性激酶同源物（MCK1）的基因组序列。该同源物由7265个碱基对组成，包含11个外显子和10个内含子。由于MCK1在光照和黑暗条件下均持续表达，因此光不太可能直接影响MCK1的表达，尽管该蛋白的活性可能受光影响。在表现出光调节重力性的品种中，我们假设MCK1或其同源物在建立正向重力性所需的生长素不对称性方面发挥作用。
