Production of species-specific Meloidogyne populations for the identification of resistance in germplasm collections

Field populations sometimes are a mixture of species and genotypes, which makes them unsuitable for resistance screening against root-knot nematodes. To solve this problem, a special protocol was developed to produce species-specific populations originating from single juveniles and to prevent contamination of inoculum of species-specific populations by other aggressive Meloidogyne species. These populations are representative of the type races occurring in the Netherlands. Before multiplication of the egg mass, the Meloidogyne female was identified by isozyme patterns of esterase (Est) and malate dehydrogenase (Mdh). The Petri dish method was evaluated to study the infection process of M. hapla, M. chitwoodi, and M. fallax on potato roots. High infection levels were obtained following inoculation with a water suspension of juveniles. The potential use of the Petri dish method for screening for resistance was assessed by inoculation of juveniles of Globodera species on roots of susceptible and resistant potato cultivars, resulting in clear differential reactions. During this study, a deviating group of field populations was distinguished based on isozyme band patterns. It was later described as a new species, M. fallax. Production de populations de Meloidogyne specifiques de l'espece en vue de l'identification de la resistance dans les collections de germplasmes - Les population des Meloidogyne rencontrees au champ peuvent etre des melanges d'especes et de genotypes et de ce fait ne conviennent pas pour tester la resistance a ces nematodes. Afin de surmonter cette difficulte, un protocole particulier a ete mis au point visant, a partir d'un seul juvenile, a produire des populations specifiques de l'espece et a eviter la contamination de ces populations par d'autres especes agressives de Meloidogyne. Ces populations sont representatives des races types presentes aux Pays Bas. En prealable a la multiplication de la masse d'oeufs, il a ete realise une pre-identification de la femelle a l'aide de profils esterasiques concernant l'esterase (Est) et la malate deshydrogenase (Mdh). La methode dite des boites de Petri a ete testee en vue de l'etude du processus d'infestation de M. hapla, M. chitwoodi et M. fallax sur des racines de pomme de terre. Grace a ce systeme, des taux d'infestation eleves sont obtenus apres inoculation a l'aide d'une suspension de juveniles dans l'eau. Les potentialites de la methode des boites de Petri ont ete confirmees par inoculation de juveniles de Globodera dans des racines de cultivars de pomme de terre sensibles et resistants, lesquels ont montre des reactions tres differentes. Au cours de ces recherches, un groupe aberrant de populations sauvages a pu etre distingue grace aux profils des isozymes, groupe decrit ensuite comme une espece nouvelle, M. fallax.

TAXONOMIC STUDIES ON CULTIVATED AND KOREAN NATIVE GENUS PYRUS PLANTS BY MULTIVARIATE AND ISOZYME ANALYSIS

Fifty nine morphological characters and isozyme band patterns of glutamate oxaloacetate transminase, peroxidase, glucose phosphate isomerase from fully expanded leaves were used for taxonomic study on 51 taxa consisted of Korean native and principal cultivars of the genus Pyrus. Taxonomic relationships were analyzed by complete cluster analysis method based on Euclidean taxonomic distance of IBM PC SPSS/PC+(ver. 3.0). Among the 39 qualitative morphological characters, a great deal of variations among 51 taxa were observed in immature fruit shape, skin lusterness, hair density on pedicel, anther color, shape of leaf apex and base, hair density on leaf surface, and leaf margin. Considerable variations were found in most tested quantitative characters except in the number of petals and styles. More reliable taxonomic results could be obtained by comparing morphological characters rather than examining isozyme band patterns. Even though there were considerable differences depending upon the methods of investigation, classification of the genus Pyrus by using isozyme band patterns was proved to be a good tool for rapid taxonomic studies.

Inheritance and linkage relationships of 6-phosphogluconate dehydrogenase isozymes in soybean

The inheritance of 6-phosphogluconate dehydrogenase (6-PGD) in dry seeds of cultivated and wild soybean was studied electrophoretically. There are four 6-PGD anodal bands that are controlled by three loci. Bands 1 and 3 are homodimers, whereas band 2 is the interlocus heterodimer of bands 1 and 3, which are products of the Pgd1 and Pgd2 loci, respectively. Both Pgd1 and Pgd2 loci have three codominant alleles (Pgd1-a, Pgd1-b, Pgd1-c and Pgd2-a, Pgd2-b, Pgd2-c) and each of the alleles specifies an isozyme band. The two variants of the fourth band are the result of two codominant alleles (Pgd3-a and Pgd3-b) of the Pgd3 locus. The Pgd3-a allele is found only in PI486.220, a Glycine soja accession from Japan. The Pgd2 is linked to Ap, Ti, and Lap1 in the order of Ap–Ti–Lap1–Pgd2 and belongs to linkage group 9. Key words: soybean isozymes linkage, genetics of Pgd loci.

Lactic Dehydrogenase of Human Chronic Lymphocytic Leukemic Leukocytes

Lactic dehydrogenase was quantitated and its isozyme pattern studied in the leukocytes of 10 patients with chronic lymphocytic leukemia. There was a wide range of LDH activity, although all isozyme patterns by starch-gel electrophoresis showed greatest activity in the No. III isozyme band. Comparison of the rate of migration of the leukemic leukocyte LDH with LDH from normal leukocytes and erythrocytes showed no difference in migration rate, suggesting that the LDH of chronic lymphocytic leukemic leukocytes does not differ in electrical charge from LDH of normal leukocytes.