Genetic instability in protoclones of potato (Solanum tuberosum L. cv. 'Bintje'): new types of variation after vegetative propagation.

The transmission of variation from protoplast-derived plants of tetraploid potato cultivar 'Bintje' to tuber progeny was examined. The morphological alterations of a majority of the variant protoclones were transmitted to corresponding tuber progeny. Some of the normal and variant protoclones gave new phenotypes, or segregated into parental and new phenotypes after vegetative propagation.

Effect of ammonium on nitrate utilization by roots of dwarf bean.

The effect of exogenous NH(4) (+) on NO(3) (-) uptake and in vivo NO(3) (-) reductase activity (NRA) in roots of Phaseolus vulgaris L. cv Witte Krombek was studied before, during, and after the apparent induction of root NRA and NO(3) (-) uptake. Pretreatment with NH(4)Cl (0.

Growth and Differentiation of Callus Derived from Leaf and Stem Internodes of Haplopappus gracilis (Nutt.) Gray.

Attempts were made to obtain plant regeneration in vitro from leaf tissue and stem internodes of Haplopappus gracilis. The morphogenetic effects of several combinations of auxin/kinetin and light with three types of basal media were investigated. A modified White's medium supplemented with IAA gave optimum callus growth, and permitted root and shoot differentiation.

The role of peroxidases in pistil-pollen interactions.

The majority of pistil peroxidases are involved in processes related to growth, development and senescence. Only the tissue specific peroxidases in the transmitting tissue of the style may play a direct role in the regulation of pollen tube growth. The pollen peroxidases may function mainly in growth regulation and tube wall formation and play a role in the interaction between pollen and pistil by metabolizing the phenolic compounds in the pistil.

Flow-cytometric characterization and sorting of plant chromosomes.

Flow cytometric measurements of DNA frequency distribution were used to follow the synchronization process in suspension cells from Haplopappus gracilis (2n=4). Metaphase chromosomes were isolated from these synchronized cells and both the acro- and metacentric chromosomes were sorted by flow cytometry based on the different DNA contents. Possible applications of this procedure in fundamental genetics as well as practical plant breeding are discussed.

A simple method for the isolation of allelic series using male-linked translocations.

Using Adh null alleles a genetic sexing technique is being developed in Ceratitis capitata. In order to facilitate the isolation of a whole series of null alleles at this locus a technique utilizing male-linked translocations is described. It provides a simple efficient and general method for the isolation of any allelic series in species where little genetic information is available.

Utilization of nitrite and nitrate by dwarf bean.

The uptake and conversion of NO 2 (-) and the effect of NO 2 (-) on the uptake and reduction of NO 3 (-) were examined in N-depleted Phaseolus vulgaris L. Nitrite uptake at 0.1 mmol dm(-3) was against an electrochemical gradient and became constant after one or two initial phases.

Mechanism of peroxidase isoenzyme induction in pollinated Nicotiana alata styles.

A comparative study on the induction of peroxidase isoenzymes, specifically number 10 (P-10) in Nicotiana alata styles revealed significant differences between the various plants of an inbred progeny. In some plants the ageing-induced increase in P-10 activity was very low, whereas in some others, it was relatively high. Pollination accelerated this increase, independent of the pollen genotype.

Effect of exogenous and endogenous nitrate concentration on nitrate utilization by dwarf bean.

The effect of the exogenous and endogenous NO(3) (-) concentration on net uptake, influx, and efflux of NO(3) (-) and on nitrate reductase activity (NRA) in roots was studied in Phaseolus vulgaris L. cv. Witte Krombek.