Expression of the pea (Pisum sativum L.) alpha-tubulin gene TubA1 is correlated with cell division activity

• Published in: Plant molecular biology 1999-11, Vol.41 (5), p.601-614
• Main Authors: Stotz, H.U, Long, S.R
• Format: Article
• Language: English
• Subjects: beta-glucuronidase; c-myc gene; Cauliflower mosaic virus; cell division; Cell Division - genetics; Epitopes - genetics; Epitopes - metabolism; Fluorescent Antibody Technique, Indirect; gene expression; Gene Expression Regulation, Plant; gene transfer; genes; genetic regulation; genetic transformation; Glucuronidase - genetics; Glucuronidase - metabolism; histochemistry; Kinetics; leaves; Medicago sativa; Medicago sativa - genetics; Medicago sativa - microbiology; Medicago truncatula; messenger RNA; Microtubules - metabolism; morphogenesis; nodulation; Pisum sativum; Pisum sativum - cytology; Pisum sativum - genetics; Plants, Genetically Modified; promoter regions; Promoter Regions, Genetic - genetics; Proto-Oncogene Proteins c-myc - genetics; Proto-Oncogene Proteins c-myc - metabolism; recombinant DNA; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; reporter genes; Rhizobium; RNA, Messenger - genetics; RNA, Messenger - metabolism; root nodules; root tips; roots; seed inoculation; Sinorhizobium meliloti; Sinorhizobium meliloti - growth & development; Symbiosis; Tissue Distribution; transgenic plants; TubA1 gene; tuba1 promoter; tubulin; Tubulin - genetics
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1006338401808

Microtubules are thought to be major determinants of plant morphogenesis, through effects on planes of cell division and on directions of differential cell expansion. In differentiation and redifferentiation processes, tubulin expression may prove a useful early indicator of cell activity. We examined the expression and localization of the pea alpha-tubulin gene TubA1 in situ and in transgenic alfalfa (Medicago sativa) to explore its use as a probe for plant development, and as a test case for correct developmental expression between two legume species commonly compared for studies of symbiosis with Rhizobium. The TubA1 mRNA was more abundant in root tips and immature leaves than in other tissues of pea. The promoter of TubA1 was fused to beta-glucuronidase (GUS) to analyze alpha-tubulin expression in transgenic alfalfa. Transient assays indicated that the TubA1 gene is transcribed at moderate levels compared to the cauliflower mosaic virus (CaMV) 35S promoter. Histochemical staining for GUS activity confirmed a correlation between TubA1 expression and cell division in nodules, roots and leaves. TubA1 promoter activity was first detected in the inner cortex of the root between 18 h and 24 h after spot inoculation with Rhizobium meliloti. Expression of a c-myc epitope fused to the carboxyl-terminus of TubA1 resulted in an incorporation into the microtubular cytoskeleton, demonstrating the effectiveness of at least one epitope tag ion creating functional tubulin fusions.