Allozyme variation in cultivars of Cucurbita pepo L.

Summary Cultivars of Cucurbita pepo were analyzed for their isozyme phenotypes by horizontal starch gel electrophoresis. Considerable allozymic variation was observed between cultivars, especially in the aspartate aminotransferase and malate dehydrogenase isozyme systems. Each of the five fruit types represented in the 21 cultivars tested (zucchini, pumpkin, spaghetti, acorn, scallop and yellow straightneck) could be distinguished by specific allozymes or combination of allozymes. Cultivars within a fruit type gave very similar allozyme phenotypes and often could not be distinguished on the basis of the 6 assays used. Despite the outcrossing nature of the species, allozyme polymorphism within most cultivars was low and did not seriously interfere with the analysis. Approximately half of the hybrid lines tested gave heterozygous phenotypes at one or more loci, indicating that such loci could be used to screen for the percentage of hybrid seed obtained from crosses.     

Identification of rape seed cultivars (Brassica napus) by starch gel electrophoresis of enzymes

Summary Isozyme patterns were used to characterize ten commercial rape seed (Brassica napus) cultivars. Extracts of cotyledons were made 4–7 days after germination and separated by electrophoresis on starch gels. A sample of more than 100 plants of each variety was analysed and stained for 4 polymorphic enzyme loci (Lap, Gpi, Acon, and Sdh). Therewith, it was possible to distinguish all ten rape varieties qualitatively by at least one typical enzyme pattern. Further, it could be demonstrated that all pairs of varieties showed clear qualitative differences in isozyme patterns, when only tow loci were screened (Acon, Sdh). Using ² test of homogeneity all pairs of varieties differ significantly in their frequencies of isozyme patterns for Acon and in all but one for Sdh.     

Identification of broad bean cultivars based on isozyme patterns

Summary With the increasing rate of new cultivar production for different crop plants, there is great need for methods of identifying each cultivar discriminatingly. Starch gel electrophoresis was employed to study the differences between the esterase and cathodal peroxidase isozyme patterns of 40 broad bean (Vicia faba L.) cultivars. A total of 10 and 17 medium to darkly stained bands were obtained for esterase and peroxidase systems, respectively. Bands from each enzyme system could be gropuped into three zones. Bands belonging to zone 1 of esterase (E₁) and zones 2 and 3 of peroxidase (P₂ and P₃) were quite distinct, stained intensely, and were especially useful for identification purposes.The differences in banding patterns among cultivars of the same origin were as great as those of cultivars of unrelated origin. A large proportion of the cultivars could be completely differentiated using both of the isozyme systems. There were no bands present in either enzyme system which were common to all cultivars.     

Expression of heritable biochemical markers from various pecan tissues

Summary Isozyme expression of malate dehydrogenase (MDH), phosphoglucomutase (PGM), and phosphoglucose isomerase (PGI) were examined from 12 tissues of pecan by starch gel electrophoresis. Tissue type, stage of development, and extraction method had little effect on isozyme expression of MDH or PGM but did influence PGI expression. Additional PGI bands were observed from seed tissue and soaked pollen. A direct relationship was observed between PGI expression from seed tissue and eventual expression from the germinated seedling. Additional PGI bands from soaked pollen were thought to be produced from structural changes and not due to more efficient extraction. The genotype of immature pecan seeds could be determined for Mdh-1, Pgi-2, and Pgm-1 provided cellular endosperm had developed. Watery endosperm did not contain detectable levels of the study enzymes. The advantages of uniform isozyme expression among various tissues and ability to determine the genotype of immature pecan seed are discussed.     

Identification and polymorphism of cultivars and wild ecotypes of safflower based on isozyme patterns

Summary Acid phosphatase and cathodal peroxidase isozyme patterns were used to identify nine introduced and five local cultivars of common safflower (Carthamus tinctorius L.) and seven ecotypes of wild safflower (C. oxyacantha Bieb.). Nineteen and nine bands, respectively, were readily observed for the phosphatase and peroxidase systems in the extracts from seedling shoots. Results indicated that both systems could be used jointly for complete identification of all the 21 seed sources used.Band frequencies and polymorphic indices (PI) were determined from acid phosphatase patterns using at least 92 individual seedlings of five introduced and five local cultivars and three wild ecotypes. Band frequencies ranged from complete absence in some to total presence in other populations. The mean PI for the introduced, local and wild safflowers were found to be 0.069, 0.052 and 0.058, respectively.The banding patterns of either enzyme system were similar in some instances for the cultivated and wild safflowers and there was as much variation between two cultivars as between a cultivar and a wild ecotype, indicating close genetic relationships between C. oxyacantha and C. tinctorius.     

Species affinities between Cajanus cajan and some Atylosia species based on esterase isoenzymes

Summary Esterase isozymes were studied in seed extracts of Cajanus cajan and six Atylosia species by polyacrylamide gel electrophoresis and isoelectrofocusing. The isozyme patterns were stable and accession specific. Within the accessions of the Atylosia species, A. albicans and A. scarabaeoides showed three common bands indicating that they are more closely related to each other than to the other species. Of the accessions of Atylosia only A. cajanifolia shares the esterase isozyme of C. cajan and hence seems to be the closest wild relative of C. cajan.     

小麦腺苷二磷酸葡萄糖焦磷酸化酶同工酶基因型与酶活性及淀粉含量的关系

采用非变性聚丙烯酰胺凝胶电泳鉴定了我国60个代表性小麦品种的腺苷二磷酸葡萄糖焦磷酸化酶(AGP)同工酶基因型, 并测定了AGP活性及总淀粉含量, 以明确小麦籽粒AGP同工酶基因型组成及其与AGP活性和淀粉含量的关系。结果表明, AGP有AGPa、AGPb、AGPc和AGPd 4个等位基因位点, 其出现频率分别为96.7%、80.0%、86.7%和16.7%; 共检测到5种基因型, 其中基因型AGPabc出现频率最高, 为46.7%。不同基因型的品种间AGP活性和总淀粉含量差异显著(P<0.05)。其中具有基因型AGPabcd的品种酶活性及总淀粉含量最高, 表明小麦籽粒中不同AGP同工酶基因型对酶活性及淀粉含量有不同遗传效应。     

Association of isozyme genotypes with agronomic and seed composition traits in soybean

Summary Two crosses between Glycine max (L.) Merr. and G. soja Sieb. & Zucc. parents were used to study the association between isozyme marker loci and agronomic and seed composition traits in soybean. The parents possessed different alleles at six isozyme loci for Cross 1 (A80-244036 × PI 326581) and at eight isozyme loci for Cross 2 (A81-157007 × PI 342618A). A total of 480 BC₂F_4:6 lines from the two crosses was evaluated for 13 traits in two environments. Lines were grouped in locus classes from 0 to 5 according to the number of loci homozygous for the G. soja alleles that they possessed. Within each locus class, each isozyme genotype was represented by five random lines.Selection for G. max alleles at the isozyme loci was not effective in recovering the recurrent parent phenotype in either cross. In cross 1, however, BC₂F₄-derived lines in the 0- or 1- locus class more closely resembled the G. max parent than lines in the 4- or 5- locus classes for most of the agronomic and seed composition traits evaluated. Significant associations were found between particular isozyme genotypes and every trait analyzed. The estimated effect of genes linked to the Pgm1 locus was a delay in maturity of 6.0±3.4 days. In cross 1, the Idh2 locus was associated with a significant effect on linolenic acid content. The percentage of variation accounted for by the models of estimation varied according to the heritability of the trait. The R² was high (up to 78%) for maturity, lodging, and vining, and low (up to 21%) for seed yield. Most of the variation was associated with the BC₂F₁ family from which the lines were derived. There was little evidence that digenic epistasis was an important source of variation.Journal Paper No. J-13505 of the Iowa Agric. Home Econ. Exp. Stn., Ames, IA, Project 2475.     

Association of isozyme markers with quantitative trait loci in random single seed descent derived lines of lentil (Lens culinaris Medik.)

Summary Polymorphism at isozyme loci was used to locate factors responsible for variation in quantitative traits of lentil. Eight sets of random single seed descent (RSSD) derived lines were developed by advancing individual F₃ plants of interspecific (L. culinaris Medik. × L. orientalis Boiss.) hybrids to the F₆. The RSSD lines in each of the eight sets differed for alleles at 2–8 isozyme loci. In each set, association of isozyme loci with variation in seven quantitative traits (days to flower, days to mature, plant height, biomass, seed yield, harvest index, seed weight) was determined for each pairwise combination of a quantitative trait with a marker locus. Loci affecting variation in all seven quantitative traits were detected by their association with 14 isozyme markers (Aat-c, Aat-m, Aat-p, Adh-1, Fk, Gal-1, Gal-2, Lap-1, Lap-2, Pgd-p, Pgi, Pgm-c, Pgm-p, Skdh). The known position of 10 the 14 isozyme loci on the lentil genetic map was used to mark the genomic regions for possible location of associated quantitative trait loci (QTL). Detected QTL were found to be located in six of the seven linkage groups on lentil genetic map. Regions of the genome represented by linkage groups, 1, 5 and 7 appeared to affect a greater number of traits than other genomic regions represented by linkage groups 2, 3 and 4. Results indicated that the mean expression of quantitative traits at segregating marker locus classes can be used to locate the genetic factors in lentil which influence the behavior of economically important traits.     

Genetic variation within and between two cultivars of red clover (Trifolium pratense L.): Comparisons of morphological,isozyme, and RAPD markers

Summary Morphological, isozyme and random amplified polymorphic DNA (RAPD) markers were used to estimate genetic variation within and between cultivars of red clover (Trifolium pratense L.), an important temperate forage legume. Two cultivars of red clover, Essi from Europe and Ottawa from Canada, were evaluated. Six monogenic morphological characters were observed for 80 plants from each of these two cultivars. All six morphological loci were polymorphic in the cultivar Essi whereas only four loci were polymorphic in the cultivar Ottawa. Forty plants from each cultivar were assayed for isozyme markers. A total of 21 enzyme-coding loci with 43 alleles was detected using twelve enzyme systems. Thirteen and nine of these loci were polymorphic in Essi and Ottawa, respectively. The mean number of alleles per locus was 1.81 in Essi and 1.67 in Ottawa. Seventeen random 10-mer primers were screened for RAPD markers. Nine primers which gave clear and consistent amplified products were used to assay 20 individuals from each cultivar. Each primer gave from 7 to 20 amplified bands with an average of 14.8 bands per primer. One hundred and eight of 116 putative loci were polymorphic in Essi and 90 of 98 loci were polymorphic in Ottawa. High within-cultivar variation was observed in both cultivars using both isozyme and RAPD markers. This high polymorphism makes these markers useful for germplasm characterization and genetic studies in red clover.     

A tetraploid hybrid plant from 4x × 2x crosses in Vitis and its origin

To study the origin of unreduced (2n) gametes in diploid Vitis cultivars, we surveyed the occurrence of tetraploid hybrid seedlings from 40 interploid crosses with five tetraploid and seven diploid cultivars. A total of 250 seedlings from the interploid crosses were established through embryo culture and by seed sowing. In 20 2x × 4x crosses, no tetraploid hybrid seedlings were derived from 8,902pollinations. In 20 4x × 2x crosses, two tetraploid hybrid seedlings were obtained from 8,057 pollinations. Investigation of isozyme genotypes of the two tetraploid seedlings using three variable enzyme systems indicated that one of the two seedlings resulted from the union of a diploid egg with a 2n male gamete and that failure of second meiotic division resulted in the formation of the 2n male gamete. The percentage of giant pollen grains in `Muscat Bailey A', a pollen parent of the tetraploid seedling, was relatively high(about 5.9%) and 10.9% of the giant pollen grains germinated on agar medium. These results suggested that 2n pollen of diploid cultivars are useful for breeding tetraploid grape. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of Phaeosphaeria nodorum-induced seed shrivelling on subsequent wheat emergence and plant growth

Summary The bread wheat cultivars Pasqua and Katepwa, and durum wheat cultivars Kyle and D8257 were used to test the effects of sowing Phaeosphaeria nodorum-shrivelled seed. In a controlled environment, emergence, tillering, and dry weight of seedlings were compared at two sowing depths. Emergence, tillering and plant dry weights were also determined in field plots in 1992 and 1993, as were yield and thousand kernel weight (TKW) in plants inoculated with P. nodorum. Under controlled conditions the level of shrivelling did not affect emergence at depths of 25 mm and, except for Katepwa, 50 mm. Deeper seeding reduced emergence regardless of the level of shrivelling. Seeding depth did not affect dry weight of roots and shoots and the effect on tillering was inconsistent in the two years. Dry root weight was positively correlated with original seed size and decreased with level of shrivelling. In the field, seedling emergence of severely shrivelled seed was significantly lower in Katepwa and Pasqua. Tillers per plant appeared to increase with increased level of shrivelling, but was significant only for D8257 in one year. Dry tiller weight was inversely related to tillering and decreased consistently with level of shrivelling. Excepting Pasqua, in one year, yield and TKW did not differ between plots originating from plump or shrivelled seed. Inoculation with P. nodorum caused a significant reduction in TKW and yield in all cultivars but Kyle. Seed shrivelled due to P. nodorum was in general found to be as suitable as plump seed for growing a wheat crop.     

Genetic distance and its association with heterosis in peas

Summary The relationship between the genetic distance of parents and both the heterosis of F₁ hybrids and the variance of F₅ lines was investigated in 72 crosses of pea (Pisum sativum L.). The genetic distance between each pair of parents was estimated, using isozyme (GDi), morphological (GDm) or quantitative (GDq) markers and finally a combination of isozyme and morphological markers (GDi+m). GDm was poorly correlated with the other measures of genetic distance, which in turn were strongly correlated with each other. Genetic distance was moderately correlated with the level of heterosis for yield over midparent in the F₁ generation, with the highest correlation obtained from GDi+m. GD was not significantly correlated with heterosis for yield over the better or best parent but it was significantly correlated with all three measures of heterosis for pods per plant and hundred seed weight. There was no correlation between genetic distance and the level of heterosis for yield and total dry matter in the F₂ generation, but GDi, GDi+m and GDq were predictive for the level of inbreeding depression in grain yield and total dry matter. When parents were high in genetic distance, crosses produced highly transgressive segregants for basal branches per plant, hundred seed weight, harvest index and onset of flowering. Genetic distance between parents was thus a useful measure for predicting a portion of hybrid performance and also of the variance of derived inbred lines. It was concluded that when choosing parents for a cross, consideration should be given to their genetic distance as well as their overall adaptation and their yield. There is considerable potential for optimising choice of parental combinations in the development of improved pea cultivars.     

Diversity in the wild potato species Solanum chacoense Bitt.

Summary The morphological and isozyme variation was studied in 22 accessions of Solanum chacoense from Paraguay and Argentina. Clear geographic groups were identified through the use of multivariate analyses. S. chacoense from mountain sites in Argentina could be readily distinguished from plains forms from Paraguay, on the basis of several correlated morphological characters. Three isozyme systems, namely phosphoglucose isomerase (PGI), glutamate-oxaloacetate transaminase (GOT) and peroxidase (PRX) were studied using starch gel electrophoresis. The banding patterns indicated that for each isozyme there were several loci, which were polymorphic. A genetic interpretation of one of the PGI loci was made, and indices of genetic diversity and genetic identity calculated. Principal components analysis, cluster analysis and genetic diversity indicated a close relationship between the geographical groups. These results are discussed in the context of in situ genetic conservation.     

Phaseolus coccineus Storage Proteins II. Electrophoretic Analysis and Erythroagglutinating Activity in Various Cultivars

Biochemical analyses of seed storage proteins of Phaseolus coccineus have been carried out to identify seventeen different cultivars. The electrophoretic patterns in native polyacrylamide gel electrophoresis (PAGE) and denaturing conditions (SDS-PAGE); evidenced qualitative and quantitative differences for the three major protein components: legumin, vicilin and phytohaemagglutinin (PHA). The results were confirmed by isoelectrofocusing (IEF) analyses. Erythroagglutination tests showed the presence of high agglutinating activity particularly in cultivars with low vicilin content. The experimental results allow one to distinguish all the cultivars by their electrophoretic spectra and agglutinating activities.     

Tolerance of spring barley cultivars to leaf rust,Puccinia hordei

Summary Fifteen spring barley cultivars were evaluated in two years for their tolerance to leaf rust, Puccinia hordei. The consistency between the results obtained in the two experiments was rather poor. The most tolerant cultivars produced low seed yields, the least tolerant ones high seed yields. A strongly negative relationship existed between harves-index and tolerance.     

Correlation of isoenzyme polymorphism and Bayoud-disease resistance in date palm cultivars and progeny

Summary Seedlings of date palm (Phoenix dactylifera L.), obtained from seven cultivars crossed with two males, were analyzed by polyacrylamide gel electrophoresis for esterase (EST), glutamate oxaloacetate transaminase (GOT), endopeptidase (ENP) and alcohol dehydrogenase (ADH) polymorphisms. Eleven, eight, five and two phenotypes were revealed for the enzymes tested, respectively. Seedlings of F₁ populations derived from Bayoud (Fusarium)-resistant and low fruit quality cultivars were characterized by a high electrophoretic polymorphism, when compared with progenies of Bayoud-susceptible and high fruit quality cultivars. In almost all cases, the most frequent electrophoretic phenotypes scored for each enzyme in different F₁ populations, were similar to those of the corresponding parent cultivars. Heterozygous phenotypes have been found for, at least, 3 loci; Got-2, Est-1 and Enp, indicating that such loci could be used to screen for hybrid seedlings. The expected Mendelian segregation of allozymes has been observed for these 3 loci, in many F₁ populations. It seems that progenies of Bayoud-resistant cultivars are characterized by a high level of electrophoretic polymorphism. The estimation of this index and the search for genetic linkage with segregating allozymes, may be biochemical criteria useful as an aid in distinguishing date palm seedling populations derived from Bayoud-resistant cultivars and suitable for breeding programs.     

Variation of seed storage proteins in landraces of common bean (Phaseolus vulgaris L.) from Basilicata,Southern Italy

Summary Twenty landraces of common bean (Phaseolus vulgaris L.) from Sarconi and Rotonda two locations of Basilicata, a Southern Italy region, were screened for variation in seed storage proteins (phaseolin and phytohemagglutinin) by polyacrylamide gel electrophoresis (SDS/PAGE and IEF-SDS/PAGE). No variation of the main seed protein fractions was observed within each landrace. Phaseolin patterns type C and T were exhibited from the landraces; the type C resulted predominant with a frequency of 70%. Only the C type was observed for the landraces of Rotonda, T and C for those from Sarconi. Two variants were observed for the phytohemagglutinin by SDS-PAGE, one was common to eighteen landraces. However, these variants submitted to IEF-SDS/PAGE resulted similar to the type T_G2described by Brown. The importance to safeguard these landraces is stressed by the observation that the more spread commercial cultivars of common bean growing in Southern-Italy had a T phaseolin pattern. A reduction of C type diffusion could produce the loss a typical trait of common bean in Mediterranean regions.     

Isozyme electrophoregrams of sixteen enzymes in five tissues of cassava (Manihot esculenta Crantz) varieties

Summary Methodology, based on starch and polyacrylamide gel electrophoresis, was developed for determining isozyme electrophoregrams (patterns) of 16 enzymes of cassava (Manihot esculenta Grantz) varieties as potential genotype markers. Extracts of five different tissues (root, stem, leaf, petiole and bud) were examined. In general, the nodal portions of the shoots gave isozyme patterns with the largest number of bands. Petiole extracts gave similar results but bud extracts gave poor patterns. The limited number of varieties that were examined could be distinguished by sequential classification on the basis of the isozyme patterns of acid phosphatase, esterase, glutamate oxaloacetase transaminase and phosphoglucoisomerase.Joint publication of the Centro Internacional de Agricultura Tropical and the Department of Plant Science (No. 716), University of Manitoba. Presented in part at the 2nd International Symposium on Biochemical Approaches to Identification of Cultivars and Evaluation of Their Properties, 5–9 May, 1985, Braunschweig, West Germany.     

Effect of floral morphology on pollination in Brassica rapa L

Summary Flower structure, especially the anther–stigma separation (ASS), is well known to affect pollination efficiency, and thus to potentially increase or decrease seed production in crops. Therefore, investigating the relationship between flower characteristics and pollination ability is crucial to a full understanding of mechanisms to improve F₁ seed production in Brassica rapa. We used image analysis to measure three flower characteristics: short stamen height (SSH); long stamen height (LSH); and pistil height (PH) in seven cultivars. We calculated the ratio of PH to LSH as an index of anther–stigma separation (ASS). We investigated the number of pollen grains (NPG) deposited on the stigma and the seed-set percentage (SSP) under open-pollination and self-pollination conditions (with and without insects, respectively). Nested ANOVA indicated significant differences between the seven cultivars in the floral characteristics except for PH. Moreover, much larger variation was observed in NPG and SSP than in floral characteristics. Although stepwise multiple regression analysis indicated that plants with relatively high PHs produced more seed under self-pollination, the number of seeds that resulted from self-pollination did not affect seed production because of incompatibility. Therefore, the effect of the spatial position of pistils on the F₁ seed production was low. Possibly other factors such as the total pollen production and visiting times of pollinators were important factors in the low yields observed in some cultivars