Department of Biological Sciences, University of Alberta, Edmonton AB, Canada.
Dev Dyn. 2011 Jan;240(1):261-70. doi: 10.1002/dvdy.22516.
The processes underlying the formation of leaf vascular networks have long captured the attention of developmental biologists, especially because files of elongated vascular-precursor procambial cells seem to differentiate from apparently equivalent, isodiametric ground cells. In Arabidopsis leaves, ground cells that have been specified to vascular fate engage expression of ARABIDOPSIS THALIANA HOMEOBOX8 (ATHB8). While definition of the transcriptional state of ATHB8-expressing ground cells would be particularly informative, no other genes have been identified whose expression is initiated at this stage. Here we show that expression of SHORT-ROOT (SHR) is activated simultaneously with that of ATHB8 in leaf development. Congruence between SHR and ATHB8 expression domains persists under conditions of manipulated vein patterning, suggesting that inception of expression of SHR and ATHB8 identifies transition to a preprocambial cell state that presages vein formation. Our observations further characterize the molecular identity of cells at anatomically inconspicuous stages of leaf vein development.
叶片维管网络形成的背后过程长期以来一直吸引着发育生物学家的注意，特别是因为长形维管前体原形成层细胞似乎是从明显等同的等径基本细胞分化而来的。在拟南芥叶片中，被指定为血管命运的基本细胞开始表达拟南芥同源框 8（ATHB8）。虽然定义 ATHB8 表达的基本细胞的转录状态将特别有启发性，但尚未鉴定出其他基因在该阶段开始表达。在这里，我们表明 SHORT-ROOT（SHR）的表达在叶片发育过程中与 ATHB8 的表达同时被激活。在操纵叶脉模式的条件下，SHR 和 ATHB8 表达域之间的一致性持续存在，这表明 SHR 和 ATHB8 的表达的开始确定了向预示着叶脉形成的原形成层细胞状态的转变。我们的观察结果进一步描述了叶片叶脉发育的解剖上不明显阶段的细胞的分子特征。
