A wild-type (WT) strain of the moss Physcomitrella patens (Hedw.) B.S.G., two mutants derived from it (PC22 and P24), and a somatic hybrid, PC22(+)P24, were analysed. Staining of metaphases revealed 54 +/- 2 chromosomes in the somatic hybrid and 27 chromosomes in the wild type and the two mutants. Using flow cytometry (FCM), DNA contents were calculated to be 0.6 pg (WT, PC22), 1.2 pg (P24), and 1.6 pg (PC22(+)P24) per nucleus, respectively. Southern hybridization provided evidence for at least one family of highly repetitive DNA and, furthermore, revealed different amounts of repetitive DNA in the four genotypes. However, these sequences cannot account for the 100% increase in the nuclear DNA amount in mutant P24, relative to wild type. In FCM analyses every moss genotype generated just one single peak of fluorescence, indicating an arrest in the cell cycle during the daytime. Thermal denaturation of wild-type DNA revealed a G+C content of 34.6% for total DNA and 38.6% for plastid DNA. A cDNA library of 1.2 x 10(6) independent clones was established, from which sequences homologous to cab and rbcS, respectively, were isolated. These genes show significant homologies to those of higher plants, and, likewise, comprise multigene families. No restriction fragment length polymorphisms could be detected between the four moss genotypes using these cDNA probes.

No abstract

Blueberries are an increasingly important h~ticultural crop in New Zealand and other coun~es. Fruit ripen over an extended period, with considerable differences in storage and other qualities. Tissue concentrations of abscisic acid (ABA), 1-aminocyciopmpane-l-carboxylic acid (ACC), malonyl-ACC and also ACC oxidase activity and ethylene evolution were determined at 5 stages of colour development on 2 harvest dates. These were related to &y matter, sucrose and reducing sugar content. ACC concentrations, and the proportion conjugated varied between harvest dates, while ethylene evolution and ABA concentrations were similar. ABA concentrations were high relative to other fruit, exceeding 10 nmole/g fw prior to full ripeness. ABA was present in higher concentration in mesocarp than in seeds or pericarp/cuticle. It is proposed that ABA is implicated in dry matter acquisition, but is not a primary determinant of colour development or ethylene regulation.