PLANT PHYSIOLOGY , Vol 108, Issue 3 929-937, Copyright © 1995 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Activation of Two Osmotin-Like Protein Genes by Abiotic Stimuli and Fungal Pathogen in Transgenic Potato Plants
B. Zhu, THH. Chen and P. H. Li
Laboratory of Plant Hardiness, Department of Horticultural Sciences and Plant Biological Sciences Program, University of Minnesota, St. Paul, Minnesota 55108 (B.Z., P.H.L.)
Osmotin-like proteins are encoded by at least six members of a multigene
family in Solanum commersonii. A genomic clone ([lambda]pGEM2a-7) that
contains two osmotin-like protein genes (OSML13 and OSML81) arranged in the
same transcriptional orientation has been isolated. Restriction mapping and
sequence analysis indicated that the two intronless genes correspond to the
previously characterized pA13 and pA81 cDNAs. To study the transcriptional
activation of OSML13 and OSML81 promoters, the 5[prime] flanking DNA
sequence (-1078 to +35 of OSML13 and -1054 to +41 of OSML81) was fused to
the [beta]-glucuronidase (GUS) coding region, and the chimeric gene fusions
were introduced into wild potato (S. commersonii) plants via
Agrobacterium-mediated transformation. Analysis of the chimeric gene
expression in transgenic potato plants showed that both 5[prime] flanking
DNA sequences are sufficient to impart GUS inducibility by abscisic acid,
NaCl, salicylic acid, wounding, and fungal infection. Low temperature
activated both chimeric genes only slightly. Infection with Phytophthora
infestans resulted in strong GUS expression from both chimeric genes
primarily in the sites of pathogen invasion, suggesting a limited diffusion
of fungal infection-mediated signals. The expression patterns of both
osmotin-like protein genes implicate their dual functions in osmotic stress
and plant pathogen defense.