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Rice endosperm UDP-glucose pyrophosphorylase (UGPase) cDNA clones were isolated by screening a lambda ZAP II library prepared from poly (A(+)) RNA of japonica rice (cv Sasanishiki) endosperm with a probe of potato UGPase cDNA. One cDNA clone, possessing about 1,700 nucleotides, contained the complete open reading frame of rice UGPase. At the nucleotide-sequence level, the UGPase cDNA of rice endosperm had high homology with the UGPase cDNA of barley endosperm (84%) and potato tuber (71%). The calculated molecular weight (50 kDa) agrees with the value determined by SDS-PAGE (51 kDa). At the amino-acid sequence level, rice UGPase has high homology with the UGPase of barley (92%) and potato (85%). The enzyme contained conserved sequence elements which are thought to be involved in substrate binding and catalytic activity. A Southern-blot analysis indicated that the gene existed as a single copy. Expression of the enzyme in rice endosperm examined by Northern-blot analysis was high at 10-15 days after heading.

Variations in endosperm polypeptides among 16 cultivars of rice were analyzed by two-dimensional gel electrophoresis. One glutelin alpha-subunit (alpha 8) with a molecular mass of 32.5 kDa was exclusively present in indica cultivars. By contrast, the glutelin alpha 3 subunit, with a molecular mass of 32 kDa, was present only in japonica and javanica cultivars. Glutelin alpha-subunits alpha 5a and alpha 5b, which have a molecular mass of 32 kDa and slightly different isoelectric points, differed among rice subspecies, i.e. the former was detected in japonica cultivars and the latter was detected in indica cultivars. Internal amino acid sequences of the indica-specific glutelin alpha-subunits alpha 5b and alpha 8, were analyzed with a gas-phase protein sequencer. Of 46 amino acid residues determined, only two residues differed, and they corresponded with the sequences deduced from type I and type II cDNAs of glutelin subfamily A, respectively. Nine polypeptides of higher molecular mass (35-90 kDa) also differed. In particular, two of these polypeptides designated B and C which were identical to Wx proteins with molecular masses of 58 kDa were strongly expressed in indica endosperms, but only weakly expressed in japonica and javanica. F1 seeds obtained from a cross between japonica and indica cultivars showed an intermediate intensity of Wx proteins and contained all nine glutelin alpha-subunits including both the japonica and indica types. In this experiment, Wx proteins designated B and C and glutelin alpha-subunits could be used to identify differences between japonica and indica cultivars.

tion from a cross between 'Norin 1' ( japonica) and 'Tadukan' (indica), and a 1:1 ratio on the basis of a This study focused on the mapping of quantitative trait loci (QTLs) BC 1 F 1 population. related to shoot regeneration from mature seed-derived calli of rice (Oryza sativa L.) by restriction fragment length polymorphismThe present experiments focused on the QTL map-(RFLP) markers. The F 2 population from a cross between 'Norin 1' ping of gene loci in relation to the rate of plant regenera-( japonica ) and 'Tadukan' (indica ), which showed lower and higher tion from mature seed-derived calli in rice. The experishoot regeneration rates, respectively, was used for QTL interval cM in each of 12 chromosomes were selected from the list published from the list by Kurata et al. (1994). After detection Lab. of Plant Breeding, Faculty of Agriculture, Yamagata Univ.,

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