The nabicol: A horticultural crop in northwestern Spain

Nabicol (B. napus L. var. pabularia) is a traditional crop in the Northwest of Iberian Peninsula (South of Galicia and North of Portugal) where it is grown during the winter season on small farms and gardens using traditional varieties. A collection of 36 populations of nabicol from Galicia (northwestern Spain) was evaluated during 2002 and 2003 in two locations and two growing seasons (spring/summer and autumn/spring) for 28 agronomic and morphological traits. The objectives of this study were to: (i) evaluate a collection of nabicol landraces from northwestern Spain, (ii) determine the suitability of this germplasm as a summer crop and (iii) study the genetic diversity among local populations. Significant differences were observed among populations for most traits. Genotype × environment interaction was significant for most of them. Spring/summer growing season could be recommended for growing nabicol but resistance to Lepidoptera pests attacking Brassica crops should be improved. Most populations had an agronomic value similar to the commercial variety. The most promising variety for horticultural use was MBG-BRS0063, which showed the highest yield. Morphological and agronomic data were subjected to cluster analysis and four groups were defined with a group clustering most populations. The low genetic diversity could be explained because populations were collected in close geographical areas and the selection made by farmers was always for a horticultural use. These results give information about the diversity and breeding value of the nabicol Spanish germplasm, which could be useful in breeding programs.     

Genetic studies in <Emphasis Type="Italic">Centrosema pubescens</Emphasis> benth,a tropical forage legume: the mating system,genetic variability and genetic relationships between <Emphasis Type="Italic">Centrosema</Emphasis> species

In this study, we used microsatellite loci to estimate the outcrossing rate of Centrosema pubescens in open-pollinated populations of 10 progenies that each contained 20 genotypes. The multilocus outcrossing rate was 27%, which suggested a mixed mating system with a predominance of autogamy. The single locus outcrossing rate was 13%. The difference was 0.040, which indicated that only 4% of outcrossing occurs in related individuals. A paternity correlation of 14% suggests that there is a low probability of finding full sibs in the progeny. Cross-amplification of the 26 microsatellite loci available for C. pubescens was evaluated across 11 different Centrosema species. Nineteen of the 26 tested microsatellites were successfully transferable across the Centrosema species. The polymorphism information content and discriminating power evaluated had averages of 0.64 and 0.77, respectively. A total of three clusters were assembled to demonstrate the genetic relationships between Centrosema species. The transferable microsatellite loci should be useful for exploiting the genetic resources of the Centrosema species and determining the outcrossing rate, which are essential for proposing effective approaches for conservation and for establishing strategies for the selection and improvement of Centrosema spp.     

Genetic diversity in a germplasm collection of Brassica rapa subsp rapa L. from northwestern Spain

In Galicia (northwestern Spain), Brassica rapa subsp. rapa L. includes turnips, turnip greens, and turnip tops. The objectives of this study are (i) to determine the genetic diversity and morphological resemblances among the B. rapa landraces of northwestern Spain in order to have information relative to the resources preserved, and (ii) to evaluate their agronomic characteristics, considering the three potential products that can be harvested. A collection of 120 landraces was evaluated for 34 morphological and agronomical traits by an augmented design at two locations. Two landraces were the most promising for turnips production (MBG-BRS0183 and MBG-BRS0256), two showed the best characteristics for turnip greens (MBG-BRS0082 and MBG-BRS0184), and three were the most appropriate landraces for turnip tops production (MBG-BRS0143, MBG-BRS0173 and MBG-BRS0401). Landraces were classified into five clusters (A–E) using the Ward–MLM (Modified Location Model) strategy: (A) included plants with the worst agronomic potential, (B) included most of the turnip populations with rosette growth habit, (C) included turnip populations without rosette growth habit, having more vigorous plants than cluster B, (D) gathered the most vigorous local varieties, with the highest early vigor, fresh matter content per leaf, and number of secondary stems per plant, and (E) landraces characterized by their earliness, large flowering periods, high numbers of secondary stems, and large seed weights. As conclusion, landraces evaluated in this work displayed enough variability to differentiate among appropriate populations for each one of the distinct crops. Their classification, using the Ward–MLM strategy, grouped accessions with similar characteristics into homogeneous categories.     

Characterization of fall and spring plantings of Galician cabbage germplasm for agronomic, nutritional, and sensory traits

Twenty one landraces of cabbage (Brassica oleracea var. capitata L.) and two of Tronchuda cabbage (B. oleracea var. tronchuda Bailey) from Galicia (north–western Spain) along with five commercial hybrids of cabbage and one commercial variety of Tronchuda cabbage were evaluated in this study in two planting dates, autumn/winter for an early harvest and spring/summer for a late harvest. Data were recorded on morphologic, agronomic, nutritional, and sensory traits. The objectives were to assess the characteristics of the Galician cabbage landraces and to compare their agronomic value with that of the commercial hybrids available in local markets, at two planting dates. Four cabbage landraces and the two Tronchuda cabbage landraces showed no head formation. At the autumn/winter season, commercial hybrids showed poor adaptation, with more plants lost after transplanting, less early vigor, and yield than the head forming landraces. However, for characters related to crop uniformity (head appearance, days to harvest, and synchrony of production), commercial hybrids did better than landraces. Regarding the sensory and nutritional values, in the autumn/winter season, accessions were tenderer, sweeter, had a better flavour, and showed higher levels of crude protein and less of crude fibre than in the spring/summer season. Landraces had higher calcium contents compared to commercial varieties. Local landraces MBG-BRS0425, MBG-BRS0452, MBG-BRS0536, and MBG-BRS0537 stood out for the most interesting traits in the autumn/winter season growing period and they could be included in breeding programs to obtain hybrids suitable to grow in this planting period.     

Mating systems in tropical forages: <Emphasis Type="Italic">Stylosanthes capitata</Emphasis> Vog. and <Emphasis Type="Italic">Stylosanthes guianensis</Emphasis> (Aubl.) Sw.

Stylosanthes capitata and S. guianensis are important forage legumes for tropical areas. The only available estimates of S. capitata and S. guianensis outcrossing rates were based on morphological markers, and the genus is considered as being mainly self-pollinated. Here we describe an estimation of the outcrossing rate in S. capitata and S. guianensis using microsatellite markers. The outcrossing rates were estimated in S. capitata and S. guianensis open-pollinated populations of 20 progenies consisting of ten individuals each. The multi locus outcrossing rate for S. capitata was estimated using 10 polymorphic loci, whereas five microsatellites were used for S. guianensis. The multi locus outcrossing rates for S. capitata and S. guianensis were 31 and 26%, respectively, suggesting a mixed mating system with predominance of autogamy. Comparison of single locus and multi locus estimates of outcrossing rates indicated that little inbreeding other than selfing occurred. The estimated Wright’s fixation index of the parental generation was lower than expected based on the multi locus outcrossing rate, possibly resulting from the use of some heterozygous breeding genotypes for the study. The data on the outcrossing rate described here are potentially useful for breeding programs and for maintenance of germplasm collections of these Stylosanthes species.     

New strategies for increasing heterozygosity in crops: Vicia faba mating system as a study case

Our research assesses the feasibility of using artificial selection on pre-mating floral traits to modify the mating system of faba bean (Vicia faba). This analysis considered two synthetic populations, which were derived from different genetic pools and had undergone five years of multiplication. For these populations, we identified floral and inflorescence traits that influence outcrossing per plant and examined the relative importance of these traits in governing yield. Codominant isozyme loci and the mixed-mating model were used to estimate the multilocus female outcrossing rate. A maternal half-sib design was used to evaluate the additive genetic component of floral and inflorescence traits, yield and yield components. Multiple regression was used to assess the effects of floral and inflorescence traits on outcrossing and yield and components of yield. The two populations exhibited mixing mating. Self-fertilization appears to result from the action of pollinating bees, so that its incidence could be modified by selection on floral and inflorescence traits that affect pollination. Floral and inflorescence traits affected individual differences in outcrossing unequally, with most variation being associated with the numbers of displayed flowers and inflorescences. Variation among plants in reward traits and in shape, although statistically significant, had limited and inconsistent influences on individual differences in outcrossing. Yield and its components varied strongly with aspects of floral display and, to a lesser extent, floral design, except for seed weight. Overall, our results imply that both outcrossing and yield could be enhanced by selection for plants that produce more inflorescences, each with relatively few flowers.     

Collard landraces are novel sources of glucoraphanin and other aliphatic glucosinolates

The glucosinolate make‐up of the edible parts of some Brassica oleracea L. crops has been investigated previously, but the leafy‐green collard (B. oleracea var. viridis) remains relatively unstudied on this topic. Due to this lack of information, a collection of US landraces was examined for glucosinolate content of leaves. The specific objectives of this examination were to compare levels of certain glucosinolates among the conserved collard landraces, identify any individuals with a distinct glucosinolate profile and determine the potential of collard as a target for chemoprotective‐based plant breeding. During winter 2010/2011, 81 collard landraces, four other viridis and four collard cultivars were evaluated in the field and harvested leaves were assayed for glucosinolates. In a subsequent study, 19 selected landraces plus the cultivars were included in a repeat trial in 2012/2013. Eighteen collard landraces contained relatively high levels of glucoraphanin in leaves in both years, and three (designated G 32575, G 32580, G 32586 in the US National Plant Germplasm System) were found to contain glucoraphanin in excess of 9.5 μmol/g DM. The examined landraces are rich sources of important aliphatic glucosinolates, previously thought to be most abundant in other B. oleracea vegetables.     

Genetic mapping of AFLP markers in Japanese bunching onion (<Emphasis Type="Italic">Allium fistulosum</Emphasis>)

Summary The first genetic linkage map of Japanese bunching onion (Allium fistulosum) based primarily on AFLP markers was constructed using reciprocally backcrossed progenies. They were 120 plants each of (P₁)BC₁ and (P₂)BC₁ populations derived from a cross between single plants of two inbred lines: D1s-15s-22 (P₁) and J1s-14s-20 (P₂). Based on the (P₂)BC₁ population, a linkage map of P₁ was constructed. It comprises 164 markers – 149 amplified fragment length polymorphisms (AFLPs), 2 cleaved amplified polymorphic sequences (CAPSs), and 12 simple sequence repeats (SSRs) from Japanese bunching onion, and 1 SSR from bulb onion (A. cepa) – on 15 linkage groups covering 947 centiMorgans (cM). The linkage map of P₂ was constructed with the (P₁)BC₁ population and composed of 120 loci – 105 AFLPs, 1 CAPS, and 13 SSRs developed from Japanese bunching onion and 1 SSR from bulb onion – on 14 linkage groups covering 775 cM. Both maps were not saturated but were considered to cover the majority of the genome. Nine linkage groups in P₂ map were connected with their counterparts in P₁ map using co-dominant anchor markers, 13 SSRs and 1 CAPS.     

Identification and validation of a core set of microsatellite markers for genetic diversity analysis in watermelon, <Emphasis Type="Italic">Citrullus lanatus</Emphasis> Thunb. Matsum. &; Nakai

Watermelon, Citrullus lanatus Thunb. Matsum. & Nakai is an important vegetable crop worldwide. Due to its narrow genetic base, detection and utilization of the genetic variations, cultivar identification and increasing genetic diversity are some important tasks for watermelon breeders. Molecular markers, especially microsatellites or simple sequence repeats (SSRs) are playing increasingly important roles for these purposes. In the present study, a core set of 23 highly informative SSR markers was developed for watermelon genetic diversity analysis. Based on whole genome sequencing of 17 watermelon inbred lines, we identified 3.9 million single nucleotide polymorphisms (SNPs) which were used to construct a SNP-based dendrogram for the 17 lines. Meanwhile, from the sequenced genome, 13,744 SSRs were developed, of which 704 were placed on a high-resolution watermelon linkage map. To develop the core set SSR markers, 78 of the 704 mapped SSRs were selected as the candidate markers. Using the SNP-based dendrogram as calibration, 23 SSR markers evenly distributed across the genome were identified as the core marker set for watermelon genetic diversity analysis. Each marker was able to detect 2–7 alleles with polymorphism information content values ranging from 0.45 to 0.82. The dendrograms of 17 watermelon lines based on SNPs, the base set of 78 SSRs and the core set of 23 SSRs were highly consistent. The utility of this core set SSRs was demonstrated in 100 commercial watermelon cultivars and elite lines, which could be placed into six clusters that were largely consistent with previous classification based on morphology and parentage data. This core set of SSR markers should be very useful for genotyping and genetic variation analysis in watermelon.     

Assessment of genetic diversity amongst Ugandan sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) landraces based on agromorphological traits and genetic markers

Sesame (Sesamum indicum L.) is one of the most important ancient oilseed crops grown throughout the tropical and subtropical regions of the world. In Uganda, most of the cultivated sesame varieties are local landraces which are frequently traded between farmers. Although these traditional landraces are an important source of genetic diversity, knowledge of their genetic diversity is still limited.Agromorphological traits and a set of published and newly developed microsatellite markers were analyzed on a collection of 121 accessions of Ugandan sesame landraces. CpSSR analysis revealed four haplotypes, whereby haplotype B was present in 96% of the individuals. The analysis of nSSR markers from 6 non-coding regions revealed a mean PIC value of 0.56 whereas the PIC value of eight selected EST-derived SSRs was 0.26. Accession-wise, the expected heterozygosity (He) varied from 0 to 0.396. AMOVA revealed that the majority of the variance occurred among the individuals accounting for 75% of the total variation, only 6% was attributed to differences among the districts, pointing towards a high gene flow (Nm = 4.476). These results are supported by the PCoA analysis as well as the NJ tree both of which revealed no clustering of the accessions according to their geographic origin. Also the statistical analysis of 10 agromorphological traits indicated no clear pattern related to the geographic origin. Such a poor grouping, indicative of considerable gene flow across geographic domains, could be explained either by a high outcrossing rate, and/or through extensive seed trading.     

Allotetraploid hybrids produced by protoplast fusion for seedless triploid <Emphasis Type="BoldItalic">Citrus</Emphasis> breeding

In connection with crop improvement strategies for marginal regions it has been proposed to increase the outcrossing rate in barley which would presuppose high and persistent pollen viability to ensure successful cross fertilisation. The present study was designed to investigate the viability of mature pollen from extruded and non-extruded anthers of cultivated and wild barley (Hordeum vulgare ssp vulgare and ssp spontaneum, respectively) in comparison with the closely related but obligatory outcrossing species H. bulbosum. Pollen viability (PV) was assessed employing the p-phenylenediamine-peroxidase-test on pollen derived from spikes or anthers immediately after collection and after treatment at 20, 30 and 40 ^∘C for 1, 2, 4, 8 and 16 h. The latter treatment was interposed after 8 h by a 10 h period of darkness at 12 ^∘C and thus called 26 h treatment, consecutively. Initial PV was high with 98% across all genotypes and even at 40 ^∘C did not fall below 80% after 8 h. After the 26 h treatment, PV of two H. vulgare genotypes originating from semi-arid regions and of H. bulbosum fell below 60% while the other genotypes retained a PV of > 80%. Viability of pollen of extruded anthers in H. vulgare ssp. spontaneum was on average slightly but significantly lower than PV of non-extruded anthers but still remained above 90%, even after the 26 h treatment at 40 ^∘C. Pollen viability of the outcrossing species H. bulbosum ranged on a very similar level as PV of H. vulgare. Results indicate that pollen of H. vulgare retains a sufficiently high level of viability to ensure successful cross-fertilisation over a period of at least 26 h even at high temperatures of up to 40 ^∘C.     

High frequency spontaneous production of doubled haploid plants in microspore cultures of Brassica rapa ssp. chinensis

Brassica rapa (syn. Brassica campestris) ssp. chinensis is an important vegetable crop, but it is relatively recalcitrant to microspore culture. One genotype each of B. rapa ssp. chinensis var. communisand var. utilis were used formicrospore culture. Embryo production of3.8–42.4 embryos/bud was obtained. A high rate of plant regeneration directly from microspore-derived embryos without subculture was achieved by an improved protocol involving replacement of culture media and reduction of sucrose concentrations after 48 h of induction,among other modifications. More than 70%of regenerated plants were spontaneous diploids. Some spontaneous tetraploid plants were also obtained from isolated microspores of both genotypes tested. These tetraploids may be directly exploited a snew varieties in a Brassica rapabreeding programme. This revised version was published online in July 2006 with corrections to the Cover Date.     

Natural outcrossing rate in Vernonia galamensis

Vernonia galamensis is a potential new industrial crop growing wild in Ethiopia. The seed oil is rich in vernolic acid, an epoxy fatty acid, which is of interest for oleochemical uses. Basic information on the reproductive system of Vernonia is still very limited. The amount of natural outcrossing was estimated at two locations in Ethiopia (Alemaya and Babile) using flower colour as a marker. Single plants with white flowers, which is a monogenic recessive trait, were planted in plots with normal pink flowers and the outcrossing rate was estimated from the frequency of pink‐flowered plants in the progeny of the white‐flowered plants. Estimates of the natural outcrossing rate ranged between individual plants from 3.5 to 16% at Alemaya and 2.5 to 12% at Babile. Vernonia galamensis can be classified as a mainly self‐pollinated species.     

Genetic diversity of Phaseolus vulgaris L. and P. coccineus L. landraces in central Italy

The genetic diversity of 66 Phaseolus genotypes was investigated, which included 14 local varieties of Phaseolus vulgaris and nine local varieties of P. coccineus, collected in Marche, central Italy. Their genetic diversity was assessed using three types of molecular marker: inter simple sequence repeats (ISSRs), nuclear gene‐tagged simple sequence repeats (SSRs) and chloroplast simple sequence repeats (CpSSRs). Phaseolus vulgaris shows a higher genetic diversity than P. coccineus for the SSRs and CpSSRs, but not for the putative neutral ISSR markers. These data suggest that selection by farmers and adaptation to heterogeneous environments has maintained the diversity in landraces of the common bean. Comparing genetic diversity in Marche with that of the American controls reveals that 71% of the local P. vulgaris varieties in Marche are of Andean origin. The two gene pools of the common bean can be found on the same farm, and there is some evidence of past hybridization events between these two gene pools.     

Variation of glucosinolates and nutritional value in nabicol (Brassica napus pabularia group)

Glucosinolate levels in leaves were determined in a collection of 36 varieties of nabicol (Brassica napus pabularia group) from northwestern Spain grown at two locations. Crude protein, acid detergent fibre, and sensory traits were also assessed by a consumer panel. The objectives were to determine the diversity among varieties in total glucosinolate content and glucosinolate profile and to evaluate their sensory attributes in relation to glucosinolate content for breeding purposes. Eight glucosinolates were identified, being the aliphatic glucosinolates, glucobrassicanapin, progoitrin, and gluconapin the most abundant. Glucosinolate composition varied between locations although the glucosinolate pattern was not significantly influenced. Differences in total glucosinolate content, glucosinolate profile, protein, acid detergent fibre, and flavour were found among varieties. The total glucosinolate content ranged from 1.4 μmol g⁻¹ to 41.0 μmol g⁻¹ dw at one location and from 1.2 μmol g⁻¹ to 7.6 μmol g⁻¹ dw at the other location. Sensory analysis comparing bitterness and flavour with variation in glucosinolate, gluconapin, progoitrin, and glucobrassicanapin concentrations suggested that other phytochemicals are probably involved on the characteristic flavour. The variety MBG-BRS0035 had high total glucosinolate, glucobrassicanapin, and gluconapin contents at both locations and could be included in breeding programs to improve the nutritional value of this vegetable crop.     

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.     

On-farm Conservation Strategy to Ensure Crop Genetic Diversity in Changing Agro-ecosystems in the Republic of Korea

With the recognition of certain limitations of ex situ methods for conservation of plant genetic resources the Convention on Biological Diversity (CBD) at the ‘Earth Summit’ in 1992 highlighted the importance of traditional knowledge of indigenous and local communities that are relevant for the conservation and sustainable use of biological diversity and gave considerable attention to on‐farm and other forms of in situ conservation. Unlike semi‐static nature of ex situ conservation the in situ or on‐farm conservation (OFC) is a dynamic evolutionary process. In developing countries like Republic of Korea, where there is a continuum between the use of traditional and modern cultivars, integration of OFC with already existing gene‐bank activities in the country will be an effective approach for conservation and sustainable use of the country's crop genetic resources. However, very little efforts have been made so far in developing strategies for OFC, therefore, in this paper we describe the importance of OFC and strategies for its development in Republic of Korea. Surveys over the last 20 years have shown that the landraces of major crops have been almost replaced by newly bred varieties in the country. But some vegetatively propagated or minor crop species are still being maintained in the farmers’ fields. We have identified crop landraces, which can be classified into four different categories from the OFC point of view. These are vegetatively propagated landraces, sexually reproduced landraces, landraces with improved varieties and landraces cultivated for the reasons of personal preference. The related issues on OFC including implementation methods from the point of national cooperative system in designated specific condition are also discussed to ensure the genetic diversity in the fast changing agro‐ecosystem of the country.     

Screening of Portuguese cole landraces (Brassica oleracea L.) with Peronospora parasitica and Plasmodiophora brassicae

Summary Forty-four landraces of Portuguese coles (Brassica oleracea L.), representing different morphotypes, were screened at the cotyledon stage for downy mildew resistance, caused by Peronospora parasitica. Two isolates of the pathogen, PHW 630 and PHW 828, were used in the experiment. The mean disease interaction phenotype varied among the landraces. Overall, the Portuguese coles have shown resistance to both isolates, particularly to isolate PHW 828. Some landraces were identified with differential reaction to the two P. parasitica isolates. Some of the Portuguese coles are, therefore, good sources of resistance genes to P. parasitica, and could be used in breeding programs or in the development of a downy mildew host differential set. Among the morphotypes tested, Couve Algarvia (ISA 207), Couve Galega (ISA 243 and 187) and Couve Glória de Portugal (ISA 84) have presented the highest resistance interaction. For the development of host differential sets, the landraces ISA 2 (Penca de Mirandela), ISA 35 (Couve de Valhascos) and ISA 600 (Penca Espanhola) could be further selected for the differentiation of P. parasitica isolates. They are resistant to PHW 828 and susceptible to PHW 643.The same morphotypes and landraces were also screened at the seedling stage for resistance to clubroot, caused by Plasmodiophora brassicae Woron.. Although some variation for resistance could be noticed in some the landraces tested, mainly Galega kale types, none of them presented a sufficient level of resistance as to be directly be useful in breeding for resistance to race 6 of P. brassicae.     

Simple sequence repeats as useful resources to study transcribed genes of cotton

Microsatellites or Simple Sequence Repeats(SSRs) are informative molecular genetic markers in many crop species. SSRs are PCR-based, highly polymorphic, abundant, widely distributed throughout the genome and inherited in a co-dominant manner in most cases. Here we describe the presence of SSRs in cDNAs of cotton. Thirty one SSR primer pairs of 220 (∼14%) tested led to PCR amplification of discrete fragments using cotton leaf cDNA as template. Sequence analysis showed 25% of 24randomly selected cDNA clones amplified with different SSR primer pairs contained repeat motifs. We further showed that sequences from the SSR-containing cDNAs were conserved across G. barbadense and G. hirsutum, revealing the importance of the SSR markers for comparative mapping of transcribed genes. Data mining for plant SSR-ESTs from the publicly available databases identified SSRs motifs in many plant species,including cotton, in a range of 1.1 to4.8% of the submitted ESTs for a given species. This revised version was published online in August 2006 with corrections to the Cover Date.