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.     

Genetic diversity among elite Bulgarian barley varieties evaluated by RFLP and RAPD markers

Genetic variation among five elite winter barley cultivars (H. vulgare L.) currently grown in Bulgaria was assessed at the molecular level using restriction fragment length polymorphism (RFLP) and randomly amplified polymorphic DNA (RAPD) markers. The present study sampled RFLPs in four well characterized multigene families in barley: the seed storage protein loci; the 18S, 5.8S and 26S ribosomal DNA loci; the loci coding for 5S ribosomal RNA and the loci coding subunit α of ATP-A complex in the mitochondrial genome. RFLPs were detected in three out of five investigated chromosomal loci in the barley cultivars studied. RAPD assay using arbitrary 10-base primers was applied to generate amplified length polymorphic markers in barley. Overall a total of 15 polymorphic phenotypes were found among the studied barley cultivars by using 11 out of 25 tested primers. All RAPDs were considered as dominant genetic markers except for two, where PCR and Southern blot analysis indicated the presence of codominant amplification products. Five RAPD polymorphisms in F₁ and F₂ progenies of the cross between Alpha and Obzor were inherited in Mendelian fashion. The determined values for the genetic variation proved a high genetic similarity among the tested cultivars. Genetic similarity (GS) calculated from RFLP and RAPD data ranged from 0.888 to 0.997 with a mean GS – 0.933. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetics of Cyst Nematode Resistance in Soybean PIs 467312 and 507354

Soybean Cyst nematode (SCN) Heterodera glycines Ichinohe is the most serious pest of soybean [Glycine max (L.) Merr.] in the world and genetic resistance in soybean cultivars have been the most effective means of control. Nematode populations, however, are variable and have adapted to reproduce on resistant cultivars over time due mainly to the narrow genetic base of SCN resistance in G. max. The majority of the resistant cultivars trace to two soybean accessions. It is hoped that new sources of resistance might provide durable resistance. Soybean plant introductions PI 467312 and PI 507354, are unique because they provide resistance to several nematode populations, i.e. SCN HG types 0, 2.7, and 1.3.6.7 (corresponding to races 3, 5, and 14) and HG types 2.5.7, 0, and 2.7 (corresponding to races 1, 3, and 5), respectively. The genetic basis of SCN resistance in these PIs is not yet known. We have investigated the inheritance of resistance to SCN HG types 0, 2.7, and 1.3.6.7 (races 3, 5, and14) in PI467312 and the SCN resistance to SCN HG types 2.5.7 and 2.7 (races 1 and 5) in PI 507354. PI 467312 was crossed to ‘Marcus’, a susceptible cultivar to generate F₁ hybrids, 196 random F₂ individuals, and 196 F_2:3 families (designated as Pop 467). PI 507354 and the cultivar Hutcheson, susceptible to all known SCN races, were crossed to generate F₁ hybrids, 225 random F₂ individuals and 225 F_2:3 families (designated as Pop 507). The F_2:3 families from each cross were evaluated for responses to the specific SCN HG types in the greenhouse. Chi-square (χ²) analyses showed resistance from PI 467312 to HG types 2.7, and 1.3.6.7 (races 5 and 14) in Pop 467 were conditioned by one dominant and two recessive genes (Rhg rhg rhg) and resistance to HG type 0 (race 3) was controlled by three recessive genes (rhg rhg rhg). The 225 F_2:3 progenies in Pop 507 showed a segregation of 2:223 (R:S) for response to both HG types 2.5.7 and 2.7 (corresponding to races 1 and 5). The Chi-square analysis showed SCN resistance from PI 507354 fit a one dominant and 3 recessive gene model (Rhg rhg rhg rhg). This information will be useful to soybean breeders who use these sources to develop SCN resistant cultivars. The complex inheritance patterns determined for the two PIs are similar to the three and four gene models for other SCN resistance sources known to date.     

Combining ability analysis of resistance to Helminthosporium leaf blight in spring wheat

Wheat breeders in South Asia are attempting to develop wheat (Triticum aestivum L.) cultivars resistant to Helminthosporium leaf blight (HLB), which occurs mainly as a complex of spot blotch caused by Cochliobolus sativus (Ito & Kuribayashi) Drechs. ex Dastur, and tan spot caused by Pyrenophora tritici-repentis (Died.) Drechs. Information on the combining ability for HLB resistance in wheat cultivars of South Asia is not available. This study was undertaken to examine the resistance to HLB in nine genetically diverse wheat parents, and to evaluate their general combining ability (GCA) and specific combining ability (SCA) effects toward determining the genetic basis of disease resistance. Nine parents were crossed in a half-diallel mating design to produce 36 populations. The F₁ and F₂ progenies, and the parents were evaluated in replicated field tests at Rampur, Nepal. Multiple disease scores were recorded, and area under the disease progress curve (AUDPC) was calculated to measure disease severity over time. The combining ability analysis was performed using Griffing's Method 2, Model 1. The parents chosen showed wide variation for resistance to HLB. They and the F₁ and F₂ progenies differed significantly for AUDPC. GCA and SCA effects were significant in both generations suggesting that additive as well as non-additive genetic mechanisms were involved in the expression of resistance in these parents. Wheat genotypes 'SW89-5422', 'G 162', 'NL 781'and 'Chirya 7' had significantly negative GCA effects for AUDPC in both F₁ and F₂ generations, suggesting their prime suitability for use in wheat breeding programs to improve resistance to HLB. The estimate of narrow-sense heritability was 0.77 in both generations suggesting that selection for HLB resistance should be effective in these crosses. The results indicate a predominance of additive gene action in the inheritance of HLB resistance in spring wheat.     

Association of agronomic traits with isozyme loci in perennial ryegrass (Lolium perenne L.)

Summary Inbred lines possessing different genotypes at three isozyme loci, PGI-2, GOT-3 and ACP-1, were produced by two generations of selfing from two contrasting cultivars of perennial ryegrass. Four separate F₂ populations were obtained by selfing or crossing F₁ plants from crosses between cultivar inbred lines. F₂ plants were scored for genotype at the three isozyme loci and for eight agronomic traits. The three isozyme loci showed independent segregation confirming that they belonged to separate linkage groups. A consistent association was observed between water soluble carbohydrate content and genotype at the PGI-2 locus. Some association was also detected between genotype at the ACP-1 locus and heading date. The relevance of these observations to ryegrass breeding programmes is discussed.     

Inheritance in Solanum aethiopicum,the scarlet eggplant

Summary Analyses of F₁ and F₂ hybrid progenies from crosses between the ancestral species Solanum anguivi and cultivars of its domesticated derivative S. aethiopicum, have proved the mode of inheritance of prickles, stellate hairs and some other morphological characters and suggested the mode for several more. Most wild-type traits were dominant: many recessive domesticated traits involved imperfect morphogenesis suggesting loss of genetic control. F₁ hybrids between cultivars show marked heterosis and are recommended for crop production.     

Characterization of graft-induced change in capsaicin content of Capsicum annuum L.

Summary Capsaicin contents were measured in the progenies from the test crosses between the strain, G₅S₁₇ derived from fruit with the graft-induced change in fruit shape and the original two cultivars, Yatsubusa (Capsicum annuum L. var fasciculatum Ilish) and Spanish Paprika (C. annuum L. var. grossum Sendt) used for grafting.The strain, G₅S₁₇ contained a lower amount of capsaicin than the original pungent cultivar Yatsubusa used as scion. The characteristic of the lowered capsaicin content in the strain has been stably inherited through seed propagation, and has also been transmitted to the progenies from the crosses with the original two cultivars used for scion or stock. These features in the capsaicin content agreed with those in fruit shape in the graft-induced change.     

Fingerprinting temperate <Emphasis Type="Italic">japonica</Emphasis> and tropical <Emphasis Type="Italic">indica</Emphasis> rice genotypes by comparative analysis of DNA markers

This paper describes the relative efficiency of three marker systems, RAPD, ISSR, and AFLP, in terms of fingerprinting 14 rice genotypes consisting of seven temperatejaponica rice cultivars, three indica near-isogenic lines, three indica introgression lines, and one breeding line of japonica type adapted to high-altitude areas of the tropics with cold tolerance genes. Fourteen RAPD, 21 ISSR, and 8 AFLP primers could produce 970 loci, with the highest average number of loci (92.5) generated by AFLP. Although polymorphic bands in the genotypes were detected by all marker assays, the AFLP assay discriminated the genotypes effectively with a robust discriminating power (0.99), followed by ISSR (0.76) and RAPD (0.61). While significant polymorphism was detected among the genotypes of japonica and indica through analysis of molecular variance (AMOVA), relatively low polymorphism was detected within the genotypes of japonica rice cultivars. The correlation coefficients of similarity were significant for the three marker systems used, but only the AFLP assay effectively differentiated all tested rice lines. Fingerprinting of backcross-derived resistant progenies using ISSR and AFLP markers easily detected progenies having a maximum rate of recovery for the recurrent parent genome and suggested that our fingerprinting approach adopting the ‘undefined-element-amplifying’ DNA marker system is suitable for incorporating useful alleles from the indica donor genome into the genome of temperate japonica rice cultivars with the least impact of deleterious linkage drag.     

Genetical analysis of resistance to Mycosphaerella pinodes in pea seedlings

Summary In studies of the inheritance of resistance, pea seedlings of seven lines in which stems and leaves were both resistant to Mycosphaerella pinodes were crossed with a line in which they were both susceptible. With seven of the crosses resistance was dominant to susceptibility. When F₂ progenies of five crosses were inoculated on either stems or leaves independently, phenotypes segregated in a ratio of 3 resistant: 1 susceptible indicating that a single dominant gene controlled resistance. F₂ progenies of one other cross gave ratios with a better fit to 9 resistant: 7 susceptible indicating that two co-dominant genes controlled resistance. The F₂ progeny of another cross segregated in complex ratios indicating multigene resistance.When resistant lines JI 97 and JI 1089 were crossed with a susceptible line and leaves and stems of each F₂ plant were inoculated, resistance phenotypes segregated independently demonstrating that leaf and stem resistance were controlled by different genes. In two experiments where the F₂ progeny of the cross JI 97×JI 1089 were tested for stem and leaf resistance separately, both characters segregated in a ratio of 15 resistant:1 susceptible indicating that these two resistant lines contain two non-allelic genes for stem resistance (designated Rmp1 and Rmp2) and two for leaf resistance (designated Rmp3 and Rmp4). Evidence that the gene for leaf resistance in JI 1089 is located in linkage group 4 of Pisum sativum is presented.     

Inheritance of tomato leaf curl virus resistance in Lycopersicon hirsutum f. glabratum

Summary Inheritance of resistance to tomato leaf curl virus (TLCV) was studied in the progenies derived from interspecific crosses between TLCV resistant Lycopersicon hirsutum f. glabratum line B 6013 and five susceptible cultivars (HS 101, HS 102, HS 110, Pusa Ruby and Punjab Chhuhara) of L. esculentum. P₁, P₂, F₁, F₂, B₁ and B₂ progenies of the five crosses were artificially inoculated with local strains of TLCV by means of the vector whitefly, Bemisia tabaci (Genn.). and the disease reaction was studied in all the crosses. Reaction of parents, F₁, F₂ and backcrosses suggests that resistance derived from L. hirsutum f. glabratum B 6013 is based on two epistatic genes, one from the wild parent and one from the cultivated one, resulting in a 13:3 segragation in the F₂.     

Effect of the black sigatoka resistance locus bs 1 and ploidy level on fruit and bunch traits of plantain-banana hybrids.

Summary Plantain (Musa spp., AAB group) cultivation is threatened by black sigatoka, an airborne fungal (Mycosphaerella fijiensis Morelet) leaf spot disease. Several traits in plantains and bananas are mainly affected by major genes. The host resistance response to black sigatoka is under the control of at least three different genes, one major recessive gene bs ₁ and two other independent additive alleles. Diploid and tetraploid plantain hybrids were evaluated for bunch weight, fruit weight, fruit length and fruit circumference. The F₁ euploid hybrids were derived from interspecific crosses between the resistant diploid wild banana Calcutta 4 and the susceptible triploid plantain cultivars Obino l'Ewai and Bobby Tannap. Linear and multiple regression models, coefficients of determination, and Durbin-Watson statistics were used to determine the single and combined effects of the major locus for black sigatoka resistance and ploidy on the different traits in the progenies. Differences in yield were mainly due to changes in weight and girth of fruit, which are affected by black sigatoka disease. The combined effect of ploidy and resistance to black sigatoka was partially responsible for the quantitative trait variation in yield. As a result of the gene interaction in the black sigatoka resistance locus bs ₁, the partially resistant and less susceptible phenotypes showed higher yield than their more susceptible full sibs.     

Increasing biodiversity of irrigated rice in Africa by interspecific crossing of Oryza glaberrima (Steud.) × O. sativa indica (L.)

The African rice Oryza glaberrima, traditionally cultivated since more than 3.500 years, is of poor agronomic performance but resistant/tolerant to various stresses and diseases. The introduction of these characters into O. sativa cultivars is difficult since crossing barriers cause spikelet sterility in F1. Backcrossing can restore fertility and recently facilitated the development of fertile O. glaberrima × O. sativa ssp. japonica hybrid progenies for rain fed systems. With the objective to gain access to African rice germplasm for improvement of irrigated rice, crosses were performed with eighteen O. glaberrima and twenty O. sativa ssp. indica accessions. In total about one hundred F1-hybrid grains were obtained. The F1 plants were all completely sterile and backcrossing (BC) to O. sativa was performed in order to restore spikelet fertility. Monitoring of Tog5681 × IR64 hybrid progenies under field conditions revealed a broad genetic diversity within the BC₁ and BC₂ populations. Some BC₁ and BC₂ progeny plants outperformed the O. sativa parent, indicating that the heterozygocity level and complementary gene action after two backcrosses are still sufficient to positively influence plant vigor. Spikelet fertility of progenies was highly variable, but almost complete fertility was already observed within the BC₁F₂ population. High spikelet fertility was preserved in one out of two analyzed BC₁F₃ families and inmost of the BC₂F₃ families. The ability to restore spikelet fertility within few generations and the potential of the genetic diversity present in interspecific progenies facilitates the development of plant types specifically designed for the African irrigated and lowland environment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification of four genes for stable hybrid sterility and an epistatic QTL from a cross between Oryza sativa and Oryza glaberrima

To further understand the nature of hybrid sterility between Oryza sativa and Oryza glaberrima, quantitative trait loci (QTL) controlling hybrid sterility between the two cultivated rice species were detected in BC₁F₁ and advanced backcross populations. A genetic map was constructed using the BC₁F₁ population derived from a cross between WAB450-16, an O. sativa cultivar, and CG14, an O. glaberrima cultivar. Seven main-effect QTLs for pollen and spikelet sterility were detected in the BC₁F₁. Forty-four sterility NILs (BC₆F₁) were developed via successive backcrosses using pollen sterility plants as female and WAB450-16 as the recurrent parent. Seven NILs, in which the target QTL regions were heterozygous while the other QTL regions as well as most of the reminder of the genome were homozygous for the WAB450-16 allele, were selected as the QTL identification materials. BC₇F₁ for the seven NILs showed a continuous variation in pollen and spikelet fertility. The four identified pollen sterility QTLs were located one each on chromosomes 1, 3, 7 and 7. Pollen sterility loci qSS-3 and qSS-7a were on chromosomes 3 and 7, respectively, which coincides with the previously identified S19, and S20, while loci qSS-1 and qSS-7b on chromosomes 1 and 7L appear distinct from all previously reported loci. An epistatic interaction controlling the hybrid sterility was detected between qSS-1 and qSS-7a.     

Introgressing resistance to bacterial and viral diseases from the middle American to Andean common bean

The genetic base of cultivars within market classes of common bean (Phaseolus vulgaris L.) is narrow. Moreover, small- and medium-seeded Middle American cultivars often possess higher yield and resistance to abiotic and biotic stresses than their large-seeded Andean counterparts. Thus, for broadening the genetic base and breeding for higher yielding multiple stress resistant Andean cultivars use of inter-gene pool populations is essential. Our objective was to determine the feasibility of introgressing resistance to Been common mosaic virus (BCMV, a potyvirus), and the common [caused by Xanthomonas campestris pv. phaseoli (Xcp) and X. campestris pv. phaseoli var. fuscans (Xcpf)] and halo [caused by Pseudomonas syringae pv. phaseolicola (Psp)] bacterial blights from the Middle American to Andean bean, using gamete selection. Also, we investigated the relative importance of the use of a landrace cultivar versus elite breeding line as the last parent making maximum genetic contribution in multiple-parent inter-gene pool crosses for breeding for resistance to diseases. Two multiple-parent crosses, namely ZARA I = Wilkinson 2 /// ‘ICA Tundama’ / ‘Edmund’ // VAX 3 / PVA 773 and ZARA II = ‘Moradillo’ /// ICA Tundama / Edmund // VAX 3 / PVA 773 were made. From the F₁ to F₅ single plant selection was practiced for resistance to the common and halo bacterial blights in both populations at Valladolid, Spain. The parents and F₅-derived F₆ breeding lines were evaluated separately for BCMV, and common and halo bacterial blights in the greenhouse at Filer and Kimberly, Idaho in 2001. They were also evaluated for the two bacterial blights, growth habit, seed color and 100-seed weight at Valladolid in 2002. All 20 F₁ plants of ZARA I were resistant or intermediate to common and halo bacterial blights in the greenhouse, but their F₂ and subsequent families segregated for both bacterial blights. Segregation for resistant, intermediate, and susceptible plants for common bacterial blight occurred in the F₁ of ZARA II. Simple correlation coefficient for common bacterial blight between the F₁ and F₁-derived F₂ families was positive (r = 0.54 P < 0.05) for ZARA II. From the F₂ to F₅ the number of families resistant to both bacterial blights decreased in both populations. Only four of 20 F₁ plants in ZARA I resulted in seven F₆ breeding lines, and only one of 32 F₁ plants in ZARA II resulted in one F₆ breeding line resistant to the three diseases. None of the selected breeding lines had seed size as large as the largest Andean parent. The use of elite breeding line or cultivar as the last parent making maximum genetic contribution to the multiple-parent inter-gene pool crosses, relatively large population size in the F₁, and simultaneous selection for plant type, seed traits as well as resistance to diseases would be crucial for introgression and pyramiding of favorable alleles and quantitative trait loci (QTL) of interest between the Andean and Middle American beans.     

Analysis of genic male sterility in Brassica oleracea

Summary The male sterility system MS-1 of Brassica oleracea was studied in order to elucidate if nucleo-cytoplasmic interactions determine this system. Crosses of male sterile MS-1 genotypes with heterozygous MS-5 genotypes gave fully fertile F₁ progenies. Selfing of seven F₁ plants resulted in five F₂ populations showing a 9:7 segregation ratio and two a 3:1 ratio for fertile and male sterile plants. Two F₂ progenies deviated from the expected 9:7 or 3:1 segregation ratios for fertile and male sterile plants. Thermosensitivity and distortion of the meiosis are suggested as the causal factors underlying the deviation of the segregation ratios. It was concluded that nuclear factors determine the male sterility in the MS-1 system, because the presence of a nucleocytoplasmic interaction in this system should have given only a 3:1 segregation ratio for fertile and male sterile plants in the F₂ generation.     

Quantitative and molecular characterization of heat tolerance in hexaploid wheat

Understanding the genetic basis of tolerance to high temperature is important for improving the productivity of wheat (Triticum aestivum L.) in regions where the stress occurs. The objective of this study was to estimate inheritance of heat tolerance and the minimum number of genes for the trait in bread wheat by combining quantitative genetic estimates and molecular marker analyses. Two cultivars, Ventnor (heat-tolerant) and Karl92 (heat-susceptible), were crossed to produce F₁, F₂, and F₃populations, and their grain-filling duration (GFD) at 30/25 ^°C 16/8 h day/night was determined as a measure of heat tolerance. Distribution of GFD in the F₁ and F₂ populations followed the normal model (χ², p > 0.10). A minimum of 1.4 genes with both additive and dominance effects, broad-sense heritability of 80%, and realized heritability of 96%for GFD were determined from F₂ and F₃ populations. Products from 59primer pairs among 232 simple sequence repeat (SSR) pairs were polymorphic between the parents. Two markers, Xgwm11 andXgwm293, were linked to GFD by quantitative trait loci (QTL) analysis of the F₂ population. The Xgwm11-linked QTL had only additive gene action and contributed 11% to the total phenotypic variation in GFD in the F₂population, whereas the Xgwm293-linked QTL had both additive and dominance action and contributed 12% to the total variation in GFD. The results demonstrated that heat tolerance of common wheat is controlled by multiple genes and suggested that marker-assisted selection with microsatellite primers might be useful for developing improved cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.     

Quantitative resistance to Botrytis cinerea from Solanum neorickii

Tomato (Solanum lycopersicum) is susceptible to gray mold (Botrytis cinerea). Quantitative resistance to B. cinerea was previously identified in a wild relative, S. neorickii G1.1601. The 122 F₃ families derived from a cross between the susceptible S. lycopersicum cv. Moneymaker and the partially resistant S. neorickii G1.1601 were tested for susceptibility to B. cinerea using a stem bioassay. Three putative quantitative trait loci (pQTL) were detected: pQTL3 and pQTL9 reducing lesion growth (LG) and pQTL4 reducing disease incidence (DI). For each pQTL, a putative homologous locus was identified recently in another wild tomato relative, S. habrochaites LYC4. pQTL3 was confirmed by assessing disease resistance in BC₃S₁ and BC₃S₂ progenies of S. neorickii G1.1601. pQTL4 was not statistically confirmed but the presence of the S. neorickii resistance allele reduced DI in all three tested populations. The reduction in LG of pQTL9 was not confirmed but rather, this locus conferred a reduced DI, similar to observations in the QTL study using S. habrochaites. The results are discussed in relation to other disease resistance loci identified in studies with other wild tomato relatives.     

Inheritance of resistance to fruit rot (Phytophthora capsici Leon.) and induction of resistance in bell pepper (Capsicum annuum L.)

Summary Fruit rot in bell pepper caused by Phytopthora capsici Leon. is a limiting factor in its commercial production. Crosses were made between Waxy Globe, a small fruited hot type, resistant to fruit rot and four highly susceptible bell pepper commercial cultivars (Chinese Giant, California Wonder, Osh, Kosh and Yolo Wonder). Studies of the F₁'s, F₂'s and backcrosses indicated that Waxy Globe carries a dominant gene imparting resistance to fruit rot. After three backcrosses with California Wonder, lines were obtained combining the resistance gene of Waxy Globe with the large fruit size and low capsaicin of California Wonder.     

Incongruity in the interspecific crosses of Vitis L. Reproductive expression in the F1 progeny

Summary F₁ progeny from three classes of crosses were studied for indications of incongruity in the form of reproductive dysfunction. Percent fruit set was found to be approximately equivalent to the additive inverse of percent aborted flowers, as the effect of shot berries was small and not significant. In interspecific crosses, barriers were manifested as reduced fruit set and seed number per berry. These two characters were used to create an index of reproductive efficiency. Nine F₁s from crosses of most divergent class, V. riparia × V. vinifera (R × V), displayed significantly tower reproductive efficiency, percent fruit set, and seed number per berry. Four female F₁s from the least divergent class, V. riparia × V. riparia (R × R), had the highest reproductive efficiency, percent fruit set and seed number per berry, when pollinated by two V. riparia pollen sources. Seventeen F₁s from the highly-intercrossed class, V. riparia × French Hybrid (R × FH), displayed intermediate levels of reproductive efficiency, percent fruit set, and seed number per berry. The R × FH class involved V. vinifera, V. rupestris, V. aestivalis, V. labrusca, V. berlandieri, V. cinerea, and V. riparia. It is proposed that the complex intercrossing in the pedigrees of the R × FH class ameliorated incongruity. In the most divergent class, R × V, progenies of one of the V. riparia parents displayed fewer incongruity effects than progenies of the other V. riparia parents. Progeny testing of many proposed parental combinations may be used to uncover useful congruent combinations.Minnesota Agricultural Experiment Station, Scientific Journal Series No. 20835     

Electrophoretic patterns of acid soluble proteins and active isoforms of peroxidase and polyphenoloxidase typifying calli and somatic embryos of two reputed date palm cultivars in Morocco

Summary When subjected to micropropagation by tissue culture, the two reputed cultivars of date palm (Phoenix dactylifera L.); Bou-Sthammi noire, resistant to Bayoud disease and Bou-Feggous, of high fruit quality, give rise to three types of calli, called white and root-forming callus, hyperhydric and degenerating callus and friable and embryogenic callus. All explant sources, calli and germinated embryos were analysed by denaturing polyacrylamide gel electrophoresis (SDS-PAGE) for acid soluble protein composition. Phenol-oxidizing enzymes; peroxidase and polyphenoloxidase, were also, evaluated and the isoforms separated by polyacrylamide gel electrophoresis. When compared with the explant and germinated embryos, embryogenic calli of the two date palm cultivars could be identified by a concentrated polypeptide of molecular weight 27 500 and polypeptides of molecular weights 70 000 and 11 500. Hyperhydric and degenerating callus contained the polypeptide exhibiting the molecular weight 32 000. Embryogenic calli showed high levels of soluble, ionically and covalently bound peroxidases. The soluble acidic isoperoxidase of R _f 0.60, revealed in these calli and germinated embryos could be a marker of the two tissues. White and root-forming calli of Bou-Feggous cultivar were typified by soluble acidic isoperoxidases with high mobility (R _f 0.75) and anodic ionically wall-bound polyphenoloxidases similar to those of the explant sources. Polyphemoloxidase activities detected in calli and embryos were very low when compared with those of explants. Used as an early test to screen embryogenic calli of date palm, acid soluble proteins, peroxidase and polyphenoloxidase data could lead to introduce lightening and economy in the tissue culture technique.