Response to Mass Selection for Plant Height and Grain Yield in Amaranth (Amaranthus spp.)

Two landrace accessions of amaranth, UCC 192 (Amaranthus cruentus) and UCH 213 (A. hypochondriacus), were used in a mass selection experiment; five per cent of the tallest and highest yielding plants in both populations were selected for three cycles. Selection gain was largest in the first cycle for both traits. Realized heritability estimates for plant height were C.22 in the UCC 192 population and 0.49 in UCH 213, and 0.09 in both populations for yield. The results supported earlier findings for the existence of genetic variability within amaranth landrace populations.     

Interspecific hybrids and possible phylogenetic relations in grain amaranths

Summary Phylogenetic relations among the three species in grain amaranth need investigation to provide information for breeding experiments germplasm conservation efforts, and decision on evolutionary patterns in the grain types. Hybrid development from crosses between species was studied to find out genetic relationship between them. Interspecific crosses were made among Amaranthus hypochondriacus, A. caudatus and A. cruentus in the glasshouse. The F₁ plants were relatively easy to obtain but had low pollen fertility (10.3–15.1%) and low seed set. A few of these hybrids did not produce seeds. Only a few F₁ seeds obtained in crosses between A. cruentus and A. caudatus. All the F₁ plants from these crosses died at the seedling stage. Crosses between A. cruentus and A. hypochondriacus produced few seeds. Most of the F₁ plants obtained from the seeds died at the seedling stage with only four plants growing to maturity but were sterile. Based on hybrid development, it was suggested that A. hypochondriacus and A. caudatus were genetically closer than the other two combinations of species studied. A. cruentus seemed to be genetically closer to A. hypochondriacus than it was to A. caudatus.Research was supported by Grand No. AMA-KE-4-83-22. (CRG GRANT) from the National Academy of Science, U.S.A.     

A rapid and reliable PCR-restriction fragment length polymorphism (RFLP) marker for the identification of Amaranthus cruentus species

A rapid and reliable PCR-restriction fragment length polymorphism (RFLP) marker was developed to identify the Amaranthus cruentus species by comparing sequences of the starch branching enzyme (SBE) locus among the three cultivated grain amaranths. We determined the partial SBE genomic sequence in 72 accessions collected from diverse locations around the world by direct sequence analysis. Then, we aligned the gene sequences and searched for restriction enzyme cleavage sites specific to each species for use in the PCR-RFLP analysis. The result indicated that MseI would recognize the sequence 5′-T/TAA-3′ in intron 11 from A. cruentus SBE. A restriction analysis of the amplified 278-bp portion of the SBE gene using the MseI restriction enzyme resulted in species-specific RFLP patterns among A. cruentus, Amaranthus caudatus and Amaranthus hypochondriacus. Two different bands, 174-bp and 104-bp, were generated in A. cruentus, while A. caudatus and A. hypochondriacus remained undigested (278-bp). Thus, we propose that the PCR-RFLP analysis of the amaranth SBE gene provides a sensitive, rapid, simple and useful technique for identifying the A. cruentus species among the cultivated grain amaranths.     

Firm Networks and Korean Subsidiaries in the United States

ABSTRACT This article examines the role of intra‐, inter‐, and extra‐firm networks in influencing the location and investment of Korean firms and their subsidiaries in the U.S. Based on a survey of Korean subsidiaries in the U.S. in 2004, this article finds that inter‐firm relations with customers and suppliers, as well as intra‐firm relations in the form of parent firms’ knowledge of the U.S. play an important role in locational decision. Korean subsidiaries’ relationships with U.S. places are strongly influenced by home‐based practices that favor hierarchical intra‐firm organization and embedded sociopolitical extra‐firm relationships that emphasize blood, school, and regional ties. Location in U.S. industrial clusters does not increase Korean subsidiaries’ level of autonomy from parent firm's control that could help facilitate the sourcing of local knowledge and resources. Only improved intra‐firm network positionality positively contributes to increased subsidiary autonomy. Overall, the findings indicate that while inter‐firm relations may be important in locational selection among Korean firms, network norms are largely maintained through intra‐firm and, to a lesser extent, extra‐firm relations.     

Genetic effects of the soft starch (h) and background loci on volume of starch granules in five inbreds of maize

Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. This study focused on the soft starch (h) locus to identify its potentially influential role in starch particle volume distribution. The objectives were to study the genetic expression of starch particle volume of the h locus in different genetic backgrounds and the gene action conditioning starch particle volume of other loci in both normal‐starch and h‐starch backgrounds. Forty‐five populations (five intra‐inbred F_1s, 10 hybrid F_1s 10 F_2s, 10 BC₁F_1s to h/h parent, and 10 BC₁ to h:h conversion of normal parent) were planted in 1993 at two locations and in 1995 at one location. Selfed heterozygotes (±/h) in all generations provided intra‐ear comparisons of normal and h starch, and F₃ and BC₁F₂ generations provided inter‐ear comparisons. Significant differences were found between normal and h:h genotypes in all intra‐ear and inter‐ear comparisons. In all cases, general combining ability effects were highly significant, suggesting the presence of additive gene effects. Generation mean analysis of normal and h:h starch materials yielded similar results, indicating the predominance of additive and some dominance effects for other loci on starch particle volume. These results indicate the usefulness of the soft starch gene and additional genetic variation among inbreds in the improvement of starch particle volume for increased starch recovery in wet milling.     

Genetic diversity in bread wheat, as revealed by coefficient of parentage and molecular markers, and its relationship to hybrid performance

Variable results have been obtained in different crop species using geneticsimilarity (GS) estimates based on molecular markers and coefficient ofparentage (COP) to predict heterosis.This study was designed: i) to assess the level of GS among 40 breadwheat (Triticum aestivum L.) cultivars selected in Central and SouthEurope; ii) to compare GS with COP; iii) to correlate the estimates ofparental diversity with the heterotic effects detected on 149 F₁hybrids obtained by crossing the 40 cultivars according to three matingdesigns.The parental cultivars and the F₁ hybrids were grown in severallocations at normal seed density. Significant heterotic effects were detectedfor grain yield and other traits including quality attributes. The parentalcultivars were assayed for DNA polymorphisms using two classes ofmarkers: 338 RFLP and 200 AFLP^® bands were scored. GS estimates werecomputed considering each molecular marker set separately (GS_RFLP,GS_AFLP) and together (GS_TOT). Ample differentiation amongthe parental cultivars was detected with the two marker sets. Although theaverage GS_TOT (0.43) was higher than COP (0.10), the twomeasurements were significantly correlated (r = 0.36, p < 0.01).Correlations between the different estimates of genetic diversity andF₁ performance or mid parent heterosis for grain yield and otherrelated traits were in general low although statistically significant.A more detailed analysis was conducted on 28 F₁ hybridsproduced in a half diallel cross of eight parental cultivars characterized byhigh heterotic effects for grain yield. The GS estimates based on RFLP,AFLP^® markers and also on RAPD were partitioned into general andspecific components. Correlations with general and specific combiningability effects for the measured traits were in several cases statisticallysignificant but too low to be predictive and therefore exploitable in practicalbreeding.     

ISSR and SCAR markers linked to the mungbean yellow mosaic virus (MYMV) resistance gene in blackgram [Vigna mungo (L.) Hepper]

A recombinant inbred line (RIL) mapping population (F₈) was generated by crossing Vigna mungo (cv. TU 94‐2) with Vigna mungo var. silvestris and screened for mungbean yellow mosaic virus (MYMV) resistance. The inter simple sequence repeat (ISSR) marker technique was employed to identify markers linked to the MYMV resistance gene. Of the 100 primers screened, 54 showed amplification of which 36 exhibited polymorphism between the parents TU 94‐2 (resistant) and V. mungo var. silvestris (susceptible). Individual plants from 53 RIL populations were analysed and one marker (ISSR811₁₃₅₇) was identified as tightly linked to the MYMV resistant gene at 6.8 cM. Both the phenotype as well as the ISSR811₁₃₅₇ marker segregated in a 1 : 1 ratio. The ISSR811₁₃₅₇ marker was sequenced and sequence characterized amplified region (SCAR) primers were designed (YMV1‐F and YMV1‐R) to amplify the marker. Screening for the SCAR marker in the RIL population distinguished the MYMV resistant and susceptible plants, agreeing well with the phenotypic data. The ISSR811₁₃₅₇ marker was validated using diverse blackgram genotypes differing in their MYMV reaction. The marker will be useful for the development of MYMV‐resistant genotypes in blackgram.     

Segregation distortion for agronomic traits in doubled haploid lines of barley

Four barley doubled haploid populations were produced by anther culture from the reciprocal crosses between two six‐row barley cultivars, ‘Plaisant’ and ‘Orria’; the doubled haploid lines (DHLs) derived from each cross were subsequently assigned to weak or vigorous populations according to the weak or vigorous nature of the originating embryos. Well‐formed embryos at day 25 on the induction medium were considered vigorous, whereas embryos maturing later were considered weak. The classification of vigorous and weak was closely associated with the ratio of green to albino plantlets regenerated. A random set of 25 DHLs from each of the four populations were selected for field testing in a replicated trial. Furthermore, a second set consisting of a total of 454 unreplicated DHLs from the four populations were also field assessed for grain yield. Distortion during in vitro culture may impede regeneration of a random array of microspores from a given cross, and may bias genetic estimates of specific trait/marker association in genetic studies. However, no significant differences were detected in this study among the four populations for days to heading, height, grain yield and thousand‐kernel‐weight when measured on the replicated trial of 100 DHLs, nor for grain yield in the second collection of 454 entries. This suggests that the likelihood of producing improved agronomic pure lines is independent of the direction of crossing and, more importantly, independent of the time when embryos matured in the induction media, at least for these particular six‐row cultivars and for the anther culture method used.     

Inheritance of sesquiterpene lactone types within the Achillea millefolium complex (Compositae)*

Successful crossing experiments between tetraploid individuals of Achillea ceretanica, A. collina, A. distans ssp. styriaca, and A. pratensis (A. millefolium complex, Compositae) were carried out. Sesquiterpenes of 1013 hybrid plants obtained from 13 crossings were studied by qualitative thin layer chromatography (TLC). F₁-progenies from parent plants with guaianolides (GU-type), as well as the offspring of a back-cross, uniformly contained proazulenes. Diallel crosses between plants exclusively with eudesmanolides (EU-type) resulted in a 7:1 segregation-ratio of EU- and GU-plants. Two reciprocal crossing experiments between EU- and GU-parents resulted in 28.6% and 89.3% EU-individuals, as well as GU-offspring. According to these findings, the qualitative marker ‘proazulene’ (GU-type) is thought to be a recessive character of the tetraploid Achillea species studied.     

Intra‐ and inter‐specific crosses of Solanum materials after mitotic polyploidization in vitro

Mitotic polyploidization in vitro was used in selected wild Solanum species and Solanum tuberosum dihaploids. The efficiency of polyploidization by colchicine was compared with that of oryzalin. Oryzalin was more effective than colchicine (P = 0.1). The rate of non‐affected to mixoploid to tetraploid regenerants was 22 : 2.5 : 1 (colchicine) and 14 : 2 : 1 (oryzalin). Optimal concentrations and durations were 3.5 mm /24 h for colchicine and 25 or 30 μm for 24 or 48 h for oryzalin (variations in concentration and duration are necessary owing to possible diversity of responses in selected genotypes). Tetraploids were obtained from S. berthaultii, S. bulbocastanum, S. pinnatisectum, S. verrucosum and eleven S. tuberosum dihaploids. The yield of tetraploids derived from tbr dihaploids was lower than that from the wild species (P = 0.01). Tetraploid regenerants were tested in intra‐ and inter‐specific crosses. Three of 43 intra‐specific combinations (298 pollinated flowers) were successful and yielded 440 seeds. Inter‐specific crosses (138 combinations, 1672 pollinated flowers) yielded 48 seedless berries.     

Fine mapping of a <Emphasis Type="Italic">Xantha</Emphasis> mutation in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

The recessive mutation of the XANTHA gene (XNT) transforms seedlings and plants into a yellow color, visually distinguishable from normal (green) rice. Thus, it has been introduced into male sterile lines as a distinct marker for rapidly testing and efficiently increasing varietal purity in seed and paddy production of hybrid rice. To identify closely linked markers and eventually isolate the XNT gene, two mapping populations were developed by crossing the xantha mutant line Huangyu B (indica) with two wild type japonica varieties; a total of 1,720 mutant type F₂ individuals were analyzed for fine mapping using polymorphic InDel markers and high dense microsatellite markers. The XNT gene was mapped on chromosome 11, within in a fragment of ~100 kb, where 13 genes are annotated. The NP_001067671.1 gene within the delimited region is likely to be a candidate XNT gene, since it encodes ATP-dependent chloroplast protease ATP-binding subunit clp A. However, no sequence differences were observed between the mutant and its parent. Bioinformatics analysis demonstrated that four chlorophyll deficient mutations that were previously mapped on the same chromosome are located outside the XNT region, indicating XNT is a new gene. The results provide useful DNA markers not only for marker assisted selection of the xantha trait but also its eventual cloning.     

Development of CGMS system in ridge gourd [<Emphasis Type="Italic">Luffa acutangula</Emphasis> (Roxb.) L.] for production of F<Subscript>1</Subscript> hybrids

Cytoplasmic male sterile system in ridge gourd has been converted to cytoplasmic genetic male sterile (CGMS) system through the development of analogues of male sterile (MS) line, maintainer line and fertility restorer line. These lines were developed by crossing the MS mutant, regenerated through in vitro culture, with monoecious pollen parents Deepthi, Haritham, LA 101, CO 2, IC 92761 and IC 92685. All hybrids and the BC₁ generation developed by crossing with the recurring pollen parents Deepthi, Haritham and LA 101 were male sterile. Male sterile BC₁ plants have been advanced to BC₆ generation and the parental line LA 101 was proved to be a successful maintainer line, producing male sterile progeny in successive back cross generations. Analogue of cytoplasmic male sterile line, MS LA 101, was developed through back crossing and on crossing with fertility restorer lines Arka Sumeet and LA 102, this line excelled as female parent, resulting heterotic combinations. Mitochondrial marker rpS14 and SCAR Tm-53 were identified to yield male sterility specific markers whereas SSR marker 18956 has generated the male fertility specific marker. These primers are recommended for marker assisted selection of ridge gourd, for utilizing male sterility for hybrid seed production and for developing A, B and C lines in CGMS system.     

Comparison of selection procedures in breeding for seed yield in segregating sesame populations

Summary Four hundred sesame (Sesamum indicum L.) lines selected by five methods from five crosses were tested for yield and other agronomic characters in F₆ and F₇. More high yielding lines were isolated by the bulk method and in the cross involving two local cultivars when two seasons means and performance in each individual season were considered. The cross involving two exotic cultivars did not produce a single line superior to local recommended variety. The 80 highest yielding lines recorded a 10.8% increase in yield compared to the mean of 400 lines. Thirty five lines were among the top 20% both seasons with a 13.2% increase in yield. Highly significant seasonal and population effects were recorded. There were no significant differences among the methods of selection although the yield differences among lines were highly significant. Interactions of seasons × populations, seasons × methods, populations × methods and seasons × populations × methods were highly significant. The results indicate that simple and less expensive bulk method may be used with equal success as the pedigree, single seed descent or early generation testing methods when selecting for yield in segregating sesame populations. The importance of inclusion of a high yielding, locally adapted cultivar in the crossing programmes for yield breeding of sesame has also been revealed.Abbreviations BM Bulk method - EGT Early generation testing - G × E Genotype × environment - MSS Modified single seed descent - PM Pedigree method - SSD Single seed descent     

Outcrossing Rates of Experimental Populations of Cuphea lanceolate

Outcrossing rates of Cuphea lanceolata Ait., a new Dilseed crop, have not been estimated; however, this species is known to be insect-pollinated, self-compatible, and autosterile. We used five allozyme loci and the mixed mating model to estimate the outcrossing rates of experimental populations of Cuphea lanceolata Ait. grown at Corvallis, Oregon in 1987 and 1988. Populations were grown using densities of one and 27 plants m^?2. Multilocus out-crossing rate estimates of populations grown at low and high density ranged from 0.61 to 0.85 and 0.93 to 0.94, respectively. Density caused differences may be caused by differences in pollinator movement. In open plantings, e.g., space-plant nurseries, selfing rates are increased by increased within plant pollination by bumblebees, the primary pollinators of C. lanceolata in temperate zones. The movement of pollinators between plants is enforced in dense plantings. We found C. lanceolata is predominantly al-logamous, but selfing rates as great as 39.0 % were observed among space-plants; thus, the progeny of an open-pollinated individual plant grown in this type of nursery is a mixed half-sib and S₁ family. Maximum outcrossing can be achieved by using dense plantings.     

Diallel analysis of sooty stripe resistance in sorghum

Sooty stripe [Ramulispora sorghi (Ellis and Everhart) Olive and Lefebre] is a widespread foliar disease of sorghum [Sorghum bicolor (L.) Moench] in West Africa, responsible for grain yield losses up to 46%. We studied the inheritance of sooty stripe resistance in a 9 × 9 sorghum F₂-population diallel grown together with parent lines and checks in1996 under natural disease pressure at two locations in Mali. The percentage of infected leaf area was determined twice over a two-week interval during the season. At the second evaluation, the mean sooty stripe severity amounted to 13% infected leaf area at Samanko and 12% at Cinzana. The frequency distribution of the entries was approximately normal for the mean disease severity, averaged across assessment dates and locations, pointing to the involvement of multiple genes. With the data combined across the two locations, genetic differences among lines and among F₂ populations were highly significant. Genotype × location interaction variances were also significant but much smaller than the genetic variances. Broad-sense heritability estimates were 0.92 for lines and 0.94 for the F₂ populations, for the mean percentage infected leaf area across the two assessment dates. General combining ability effects (GCA) determined most of the differences among the F₂ populations. Specific combining ability effects (SCA), and the interactions of GCA or SCA with locations were also significant but less important. Line performance per se was highly correlated with GCA. Because of the high heritability and predominance of additive effects, prospects are good for the genetic improvement of resistance to sooty stripe in sorghum in Mali, using simple pedigree or recurrent selection procedures. This revised version was published online in August 2006 with corrections to the Cover Date.     

Estimation of outcrossing rate in landraces of tetraploid wheat (Triticum turgidum L.)

A study was undertaken to assess the amount of natural outbreeding in tetraploid wheat landraces of Ethiopian origin. The study consisted of two trials which were planted separately at two locations representing different environmental conditions for two consecutive seasons. The design employed was the randomized complete block with three replications. Two polymorphic loci, glume pubescence and awn condition were utilized as markers. The rate of outcrossing was based on the number of hybrids found in the recessive class of each marker. The overall level of outcrossing was higher in the pure stand trial than in the mixed stand trial. A higher rate of outcrossing occurred in the higher altitude area in the pure stand trial while the opposite was the case in the mixed stand trial. The average rate of outcrossing due to the marker loci was also different, with the long awn displaying more outbreeding tendency. Both locational and seasonal differences in the amount of outcrossing were observed. Generally, the study has revealed that there is a considerable amount of outbreeding in the landraces and that this genetic factor could play a role in preserving variation in the landrace populations. The level of outcrossing detected in this study could have a bearing on the maintenance of the genetic purity of diverse breeding lines being handled together in a breeding nursery and varietal purity in seed multiplication.     

Yield trade-off and the role of parental selection based on seed size when breeding for soybean seed protein

Alternative physiological strategies can increase protein concentration in soybean: (i) more-than-proportional increases in seed protein content (mg seed⁻¹) relative to increases in carbohydrate and oil content in large-seeded genotypes or (ii) more-than-proportional reductions in carbohydrate and/or oil content relative to protein content reductions in small-seeded genotypes. Because these strategies differentially affect crop growth and development, we hypothesized that populations developed from high-protein (HP) parents with contrasting seed sizes will present differences in how seed yield and protein concentration correlate. To test this, three breeding strategies were developed by mating high-yielding cultivars and HP ones that differ in seed sizes, reflecting the alternative strategies mentioned above. Neither tested crossing strategies showed differences in their correlation values between seed yield and protein concentration, as initially expected. Nevertheless, populations developed from crossing a HP-small-seeded parent to a HP-large-seeded one showed the highest number of transgressive segregants for protein yield. Our results showed that parent selection based on seed size has no beneficial effects on the development of high-yielding, HP soybean populations, but it might affect the number of transgressive segregants for protein yield.     

RAPD markers for discriminating tea germplasms at the inter-specific level in China

For the discrimination of tea germplasms at the inter‐specific level, four tea species and varieties (Camellia sinensis, C. sinensis var. assamica, C. sinensis var. pubilimba, C. sinensis var. kucha) and their 20 wild allied species (C. sp.) preserved in the China National Germplasm Tea Repositories (CNGTR) were investigated using randomly amplified polymorphic DNA (RAPD) markers. Fifteen primers were chosen from the 61 screened for RAPD amplification. The average DNA polymorphic frequency of RAPD primers at the inter‐specific level was 0.30, varying from 0.16 to 0.60, lower than that at the intra‐specific level. Using the presence, sometimes absence of unique RAPD markers, it was possible to discriminate 14 of the germplasms investigated. No single primer could discriminate all the 24 germplasms. However, OPO‐13 provided rich band patterns and it could discriminate 10 genotypes. The combination of two and three primers made it possible to discriminate 15 and 21 germplasms, respectively. Furthermore, the combination of band patterns or the DNA fingerprinting based on specific RAPD markers generated by OPO‐13, OPO‐18, OPG‐12 and OPA‐13 allowed the discrimination of all 24 germplasms investigated. Therefore, RAPD markers also provide a powerful tool to differentiate tea germplasms at the inter‐specific level.     

Genetic linkage between male sterility and non‐spiny trait in safflower (Carthamus tinctorius L.)

Genetic male sterility (GMS) exists naturally in safflower (Carthamus tinctorius L.). In the existing safflower GMS lines, sterile and fertile plants are distinguishable at flowering. This causes delay in fertile plants rouging and reduction in hybrid purity. In this investigation, a cross between a spiny GMS parent 13‐137 and a spiny non‐GMS parent ‘A1’ was effected. One sib cross, SC‐67, producing non‐parental‐type non‐spiny sterile and spiny fertile plants in F₃ was advanced to F₉ through sib crossing between non‐spiny sterile and spiny fertile plants. Mendelian digenic segregation was not observed for non‐spiny trait and male sterility. The results revealed strong linkage between these traits. The linkage was confirmed in F₂ generations of crosses between a non‐spiny marker‐linked GMS line (MGMS) and five elite lines. Male sterility–linked non‐spiny trait could distinguish sterile and fertile plants at elongation stage. The MGMS would be useful in production of pure F₁ hybrid seed and development of elite populations.