Analysis of the expression patterns of the Arabidopsis thaliana tubulin-1 and Zea mays ubiquitin-1 promoters in rice plants in association with nematode infection

The temporal and spatial expression of three promoters was investigated in transgenic rice plants using promoter-beta-glucuronidase (gusA) reporter gene fusions. The promoters studied were ubiquitin-1 (UBI-1) of Zea mays, Cauliflower Mosaic Virus 35S gene (CaMV35S) and a tubulin gene (TUB-1) of Arabidopsis thaliana. The TUB-1 promoter provided 7.32-fold more GUS activity in roots relative to tillers. This was significantly different from the corresponding value of 2.82-fold for CaMV35S bill not from that of 4.55-fold for UBI-1, activity of both promoters was higher in the root tips and zone of elongation than mature roots. This younger root tissue represented a declining proportion of the expanding root system with time. Older tissue expressing GUS under control of the TUB-1 promoter showed a steeper decline ill activity with time than occurred with the UBI-1 promoter. Nematode infection did not alter the overall pattern of expression from the two promoters, except that the giant cells induced by Meloidogyne incognita retained TUB-1 promoter activity as roots matured. Pratylenchus zeae invaded older root regions than M. incognita and no changes in promoter activity were detected where it fed. The results Suggest the TUB-1 promoter has characteristics that favour its use for delivering anti-feedants, such as cysteine proteinase inhibitors, to M. incognita. (C) 2002 Elsevier Science Ltd. All rights reserved.