Goormachtig S, Alves-Ferreira M, Van Montagu M, Engler G, Holsters M
Department of Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), Universiteit Gent, Belgium.
Mol Plant Microbe Interact. 1997 Apr;10(3):316-25. doi: 10.1094/MPMI.1997.10.3.316.
Upon infection of Sesbania rostrata with Azorhizobium caulinodans, nodules are formed on roots and stems. Stem nodules develop from abundantly distributed dormant root primordia. To acquire more insight into the meristem organization during stem nodule development, the expression patterns of a mitotic B1-type cyclin gene (Sesro; CycB1;1), a cyclin-dependent kinase gene (Cdc-2-1Sr), and a histone H4 gene (H4-1Sr) of S. rostrata were followed by in situ hybridization. Cdc2-1Sr transcripts were found in all cells of uninfected and infected root primordia. In uninfected root primordia, Sesro;CycB1;1 transcripts were detected in a few cells of the apical root meristem whereas H4-1Sr transcripts were abundant in this region. Interestingly, after inoculation with A. caulinodans, H4-1Sr transcripts disappeared in the root meristem and a patchy pattern of Sesro;CycB1;1 and H4-1Sr expression appeared in the cortex of the root primordium, reflecting the formation of globular nodule primordia. When bacterial invasion started, a distal nodule meristem was delimited wherein Sesro;CycB1;1 and H4-1Sr expression was concentrated. Approximately 1 week after inoculation, meristem activity ceased, indicated by the loss of Sesro;CycB1;1 and H4-1Sr expression.
用茎瘤固氮根瘤菌感染喙荚田菁后，根和茎上会形成根瘤。茎瘤由大量分布的休眠根原基发育而来。为了更深入了解茎瘤发育过程中的分生组织组织情况，通过原位杂交追踪了喙荚田菁的有丝分裂B1型细胞周期蛋白基因（Sesro; CycB1;1）、细胞周期蛋白依赖性激酶基因（Cdc-2-1Sr）和组蛋白H4基因（H4-1Sr）的表达模式。在未感染和感染的根原基的所有细胞中都发现了Cdc2-1Sr转录本。在未感染的根原基中，在根尖分生组织的少数细胞中检测到Sesro;CycB1;1转录本，而H4-1Sr转录本在该区域丰富。有趣的是，接种茎瘤固氮根瘤菌后，根分生组织中的H4-1Sr转录本消失，Sesro;CycB1;1和H4-1Sr表达的斑驳模式出现在根原基的皮层中，反映了球状根瘤原基的形成。当细菌入侵开始时，界定了一个远端根瘤分生组织，其中Sesro;CycB1;1和H4-1Sr表达集中。接种后约1周，分生组织活动停止，这由Sesro;CycB1;1和H4-1Sr表达的丧失表明。
