Wysocka-Diller J W, Helariutta Y, Fukaki H, Malamy J E, Benfey P N
Department of Biology, New York University, New York, NY 10003, USA.
Development. 2000 Feb;127(3):595-603. doi: 10.1242/dev.127.3.595.
Mutation of the SCARECROW (SCR) gene results in a radial pattern defect, loss of a ground tissue layer, in the root. Analysis of the shoot phenotype of scr mutants revealed that both hypocotyl and shoot inflorescence also have a radial pattern defect, loss of a normal starch sheath layer, and consequently are unable to sense gravity in the shoot. Analogous to its expression in the endodermis of the root, SCR is expressed in the starch sheath of the hypocotyl and inflorescence stem. The SCR expression pattern in leaf bundle sheath cells and root quiescent center cells led to the identification of additional phenotypic defects in these tissues. SCR expression in a pin-formed mutant background suggested the possible origins of the starch sheath in the shoot inflorescence. Analysis of SCR expression and the mutant phenotype from the earliest stages of embryogenesis revealed a tight correlation between defective cell divisions and SCR expression in cells that contribute to ground tissue radial patterning in both embryonic root and shoot. Our data provides evidence that the same molecular mechanism regulates the radial patterning of ground tissue in both root and shoot during embryogenesis as well as postembryonically.
scarecrow（SCR）基因的突变会导致根部出现径向模式缺陷，即丢失一层基本组织。对scr突变体地上部分表型的分析表明，下胚轴和地上花序也存在径向模式缺陷，正常淀粉鞘层缺失，因此无法感知地上部分的重力。与它在根内皮层中的表达类似，SCR在下胚轴和花序茎的淀粉鞘中表达。SCR在叶维管束鞘细胞和根静止中心细胞中的表达模式导致在这些组织中发现了其他表型缺陷。在pin-formed突变体背景下的SCR表达表明了地上花序中淀粉鞘的可能起源。对胚胎发育最早阶段的SCR表达和突变体表型的分析揭示了缺陷细胞分裂与在胚胎根和地上部分中参与基本组织径向模式形成的细胞中的SCR表达之间的紧密相关性。我们的数据提供了证据，表明相同的分子机制在胚胎发育期间以及胚胎后调节根和地上部分基本组织的径向模式形成。
