PLANT PHYSIOLOGY , Vol 113, Issue 2 511-517, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Pyrophosphorylases in Potato (V. Allelic Polymorphism of UDP-Glucose Pyrophosphorylase in Potato Cultivars and Its Association with Tuber Resistance to Sweetening in the Cold)
J. R. Sowokinos, C. Thomas and M. M. Burrell
University of Minnesota, Department of Horticultural Science, St. Paul, Minnesota 55108 (J.R.S.)
UDP-glucose pyrophosphorylase (UGPase) was cloned from six American and
nine European potato (Solanum tuberosum L.) cultivars. Restriction mapping
of the different UGPase-cDNAs with BamHI, HindIII, and EcoRI revealed that
at least two mRNA populations were present in most cultivars. Staining for
UGPase activity in nondenaturing gels of proteins extracted from developing
potato tubers yielded two major isozymes that were highly active and
appeared to be dimeric in nature. Following sodium dodecyl
sulfate-polyacrylamide gel electrophoresis, all isozymes were disassociated
into a single subunit with a molecular mass of 53 kD. Since UGPase has been
demonstrated to be a single-copy gene in the haploid genome of potato (A.Y.
Borovkov, P.E. McClean, J.R. Sowokinos, S.H. Ruud, G.A. Secor [1995] J
Plant Physiol 147: 644-652), there must be allelic differences at the
UGPase locus (chromosome 11). The two alleles, designated ugpA and ugpB,
were identified by the absence and presence of a BamHI site, respectively.
The relative band intensities of the two cDNA populations following
polymerase chain reaction amplification and agarose gel electrophoresis
were related to a potato cultivar's ability to resist sweetening when
exposed to cold temperatures.
