Establishment Of Core Collection Research Articles

Diversity of Cowpea [Vigna unguiculata (L.) Walp] Landraces in Mozambique: New Opportunities for Crop Improvement and Future Breeding Programs

Cowpea (Vigna unguiculata) is a neglected crop native to Africa, with an outstanding potential to contribute to the major challenges in food and nutrition security, as well as in agricultural sustainability. Two major issues regarding cowpea research have been highlighted in recent years—the establishment of core collections and the characterization of landraces—as crucial to the implementation of environmentally resilient and nutrition-sensitive production systems. In this work, we have collected, mapped, and characterized the morphological attributes of 61 cowpea genotypes, from 10 landraces spanning across six agro-ecological zones and three provinces in Mozambique. Our results reveal that local landraces retain a high level of morphological diversity without a specific geographical pattern, suggesting the existence of gene flow. Nevertheless, accessions from one landrace, i.e., Maringué, seem to be the most promising in terms of yield and nutrition-related parameters, and could therefore be integrated into the ongoing conservation and breeding efforts in the region towards the production of elite varieties of cowpea.

Diversity analysis and establishment of core collection among Akebia trifoliata (Thunb.) Koidz. in Qinba mountain area of China using ISSR and SRAP markers

Akebia trifoliata (Thunb.) Koidz. is a perennial woody liana that belongs to Akebia Decne. Being high-value medicinal and economic crops, different parts of the plants are utilized for producing medicines, fruit, tea, wine, edible oil, etc. A. trifoliata is mainly wild, slow growth and low reproduction. However, the fragmented habitats caused by increasingly human activities led to a sharp decline yield of wild resources. Therefore, the domestication and cultivation of this plant could be the solution. Study on the genetic diversity among individuals or populations are the basis of making its conservation strategies and germplasm selection. In this study, 242 A. trifoliata accessions of 12 populations, collected from Qinba mountain area of China, were assessed using ISSR and SRAP markers, which generated 99.4% and 98.7% polymorphism, respectively. Both ISSR and SRAP revealed the high level of genetic diversity (H = 0.31, I = 0.47, ISSR; H = 0.33, I = 0.50, SRAP), and also revealed high genetic differentiation (Gst = 0.36 for ISSR, Gst = 0.34 for SRAP) and gene flow (Nm = 1.76 for ISSR, Nm = 1.44 for SRAP). Genetic variation observed within population was higher than of among population. The Mantel Test showed that the genetic variation among populations could be explained by the geographical distances (r2 = 0.1797, p = 0.020, ISSR marker; r2 = 0.2793, p = 0.010, SRAP marker;) The results of Structure analysis and PCoA also supported clustering model. Finally, based on ISSR and SRAP data, a core collection of 56 accessions by the LDSS method was selected. Collectively, our results lay the foundation for making A. trifoliata’s conservation strategies and germplasm selection.

Development of novel simple sequence repeat markers from ramie (Boehmeria nivea L. Gaudich) and analysis of genetic diversity in its genetic resources

Boehmeria nivea (ramie), a subshrub of the Urticaceae family and an important fiber crop, has been grown in Asian countries, including Korea, for many centuries. Traditionally, in some regions of Korea, ramie leaves are also used as a major ingredient in ‘Songpyeon’ rice cakes. Despite its economic importance, the molecular genetics of ramie have not yet been studied in detail. Researchers from Yeong-Gwang Agricultural Technology Center collected genetic resources of ramie from a variety of local sites in Korea. Nuclear internal transcribed spacer sequences amplified from 90 genetic resources showed no variation in size or sequence between them or B. nivea reference samples, indicating that all the genetic resources could be taxonomically classified as B. nivea. To systematically and efficiently manage these genetic resources, we developed simple sequence repeat (SSR) markers for ramie using the magnetic bead hybridization selection method. Finally, we selected 17 SSR markers that showed possible polymorphism among the genetic resources and analyzed the genetic diversity of ramie collection. These 17 markers detected a total of 140 alleles, ranging from 3 to 17 alleles per accession. The average genetic diversity value was 0.61, ranging from 0.37 to 0.84. Average polymorphism information content was 0.56, ranging from 0.34 to 0.82. Genetic cluster analysis based on SSR data revealed that the genetic collection of ramie plants could be classified into four distinct clusters. A purity test on several of the genetic resources using polymorphic SSR markers revealed that some resources were impure. These newly developed SSR markers might be useful for diverse genetic analysis including the management of genetic collections, establishment of core collections, and cultivar identification.

Diversity studies in chickpea (Cicer arietinum)

Genetic diversity is a useful tool in gene bank management and breeding experiments like tagging of germless, identification and/or elimination of duplication in the gene stock and establishment of core collections. The present study was envisaged to measure the genetic diversity among the genotypes of chickpea (Cicer arietinum L.) and to identify divergent parents for future hybridization programmes of yield improvement. Characters like days to maturity, total pods/plant, 100-seed weight, seed yield/plant can be considered as selection criteria.

Relative efficiency of morphological characters and molecular markers in the establishment of an apricot core collection

In order to optimize the management of genetic resources, in most cases a representative sample of the germplasm collections needs to be developed. The establishment of a core collection is thus of major importance either to minimize the cost associated with the management of the associated germplasm or to apply analysis onto representative bases. In order to select a representative core collection among the Tunisian apricot germplasm of 110 accessions large, the Maximization strategy algorithm was used. This algorithm was shown to be the most convenient when using both morphological traits and molecular markers. Three core collections based on morphological characters, molecular markers or the combined data were compared. Our data indicate that both the molecular and the morphological markers have to be considered to obtain a core collection that represents the global diversity of the 110 accessions. Using this method, a subset of 34 selected accessions was found to represent accurately the 110 accessions present in the whole collection (75 to 100% for the morphological characters and 97% of the molecular markers). These results show that the combination of molecular and morphological markers is an efficient way to characterize the apricot core collection and provides an exhaustive coverage for the analyzed diversity on morphological and genetic bases.

Construction and evaluation of a primary core collection of apricot germplasm in China

As the origin center of apricots, China has the richest apricot germplasm resources. The establishment of core collections is very important for a better evaluation and utilization of apricot germplasm. In this study, 1501 apricot accessions from the initial collections in China were used to sample and establish a primary core collection. Data of 18 traits including both quantitative and qualitative were collected and used to design sampling strategy. The overall sampling strategy includes principles for grouping, sampling proportion within group and sampling method from each group. Three sampling proportions 5%, 10% and 15% were used in the study. Our results suggest that 10% was the best entire sampling ratio for primary core collection of apricots. With 10% entire sampling ratio, the optimal sampling strategy was to group samples based on their growing regions, in combination with logarithmic sampling proportion within each group. Using this sampling strategy, we have established a primary core collection with 150 accessions, and the primary core collection can well represent the genetic diversities of the entire collection. The genetic diversity of the apricot primary core collection was further analyzed using Simple Sequence Repeats (SSRs) molecular marker technique. A total of 22 polymorphic specific primers were developed and 196 alleles were detected. The average number of alleles in each locus was 8.9, suggesting that there were very rich genetic variances among the prime core collection. This also confirms that our primary core collection is a good representation of the genetic diversities of the whole collections at DNA level.

Tamanho de coleção original, métodos de agrupamento e amostragem para obtenção de coleção nuclear de germoplasma

O objetivo deste trabalho foi verificar o efeito do tamanho da coleção original de germoplasma sobre eficácia de diferentes métodos de agrupamento e de amostragem, utilizados na obtenção de coleções nucleares, e comparar esses métodos no estabelecimento de coleções nucleares. Foram simulados sete tamanhos de coleções originais e utilizadas sete estratégias de amostragem para estabelecimento de coleções nucleares, com uso de caracteres morfo-agronômicos. Oito estratégias de obtenção de coleção nuclear foram empregadas, seis com técnicas de agrupamento (Tocher e Tocher sequencial) e duas sem agrupamento (aleatória e Tocher invertido). Nas estratégias de agrupamento, foram empregadas as amostragens constante, logarítmica e proporcional. Determinaram-se a variância explicada, o valor do coeficiente de determinação, o coeficiente de coincidência e o coeficiente de coincidência do desvio-padrão entre a coleção nuclear e a coleção original. As estratégias de amostragem constante e logarítmica geram coleções nucleares representativas da coleção original. O agrupamento de Tocher sequencial é mais eficaz na representação da coleção original pela coleção nuclear do que o agrupamento de Tocher. Entre as estratégias avaliadas, a amostragem pelo método de Tocher com critério de aglomeração inverso foi a mais eficiente na geração de coleções nucleares representativas das coleções originais

Preliminary establishment of core collection in <I>Houttuynia cordata</I> Thunb of Huaihua

In order to solve the problem of the maze precision fertilizer,soil fertility evaluation,soil fertility classify and yield projections,the geographic information system with spatial information processing functions,spatial data mining techniques with spatial information analysis capabilities,expert system technology in the field of artificial intelligence,traditional information management systems and decision support system were effectively integrated in this study,and the statistical analysis method of GIS and data visualization were combined to design and implement the maize precise intelligent space decision-making system.This system had greatly improved the decision-making ability in agricultural production carried out by agricultural management.

Estratégias de amostragem e estabelecimento de coleções nucleares

O objetivo deste trabalho foi avaliar a influência da intensidade de amostragem, do tamanho da coleção de germoplasma inicial e da variância da amostragem sobre a qualidade das respectivas coleções nucleares, quanto à representatividade das coleções iniciais. Foram simulados sete tamanhos de coleções iniciais e utilizadas seis intensidades de amostragem para estabelecimento de coleções nucleares, utilizando caracteres morfoagronômicos. Determinaram-se o número de grupos formados, o coeficiente de coincidência entre a coleção nuclear e a coleção inicial e o coeficiente de determinação dos acessos amostrados para comporem a coleção nuclear. Também foi proposto o uso de uma estratégia alternativa para estabelecer coleções nucleares, de forma a maximizar a diversidade entre os acessos. O tamanho da coleção inicial influencia a intensidade de amostragem empregada na obtenção da coleção nuclear. A amostragem de acessos pelo método de Tocher, com critério de aglomeração inverso, mostrou-se eficiente na obtenção de coleções nucleares. As diferentes magnitudes de variância das coleções iniciais não influenciaram os coeficientes de determinação (R²) nem os coeficientes de coincidência entre a coleção inicial e as respectivas coleções nucleares.

Molecular Characterization of Local Spanish Peach [Prunus persica (L.) Batsch] Germplasm

A collection of 85 local Spanish peach cultivars has been studied with SSR markers. To carry out this work 42 SSRs previously developed in peach were screened to select the microsatellite loci that presented high polymorphism and that were easier to score in high resolution agarose gels. Ten SSRs were selected to identify the peach cultivars and to estimate the genetic similarity among them. The selected microsatellites resulted in the amplification of 35 fragments in the 85 genotypes studied, differentiating 46 genotypic profiles, from which 31 correspond to unique cultivars. The rest of the profiles correspond to groups of two to five cultivars and one group of 17 undistinguishable cultivars. The genetic similarity estimated from the molecular data clearly separated the flat and most of the white-fleshed peaches from the rest of genotypes that are mostly yellow non-melting local peaches. The results obtained in this work will help to improve the conservation and management of local Spanish peach germplasm allowing the establishment of core collections that represent most of the diversity conserved.

Studies on sampling schemes for the establishment of corecollection of rice landraces in Yunnan, China

The sampling scheme for a core collection from the basecollection of Yunnan rice landraces was studied, using 6,121accessions catalogued in the national genebank and 31 charactersincluding taxonomic characters, morphological characters andagronomic characters. Sampling scheme was studied at three levels,i.e., grouping principle, sampling proportion within group andsampling method from each group. Grouping principles used wereDingying's taxonomic system, Cheng-Wang taxonomic system,Yunnan rice ecological zone, Yunnan administrative district, singlecharacter and completely random sampling without grouping. Samplingproportions in each of the groups were square root, logarithm, indexof genetic diversity and fixed proportion. Clustered and randomsampling were carried out in each group. Five parameters, (indexof genetic diversity, variance of phenotypic value, variance ofphenotypic frequency, coefficient of variation and ratio ofphenotypic retained), in primary core collection were used toevaluate the validity of sampling scheme. The better samplingstrategies were grouping principles based on the two taxonomicsystems, decisions on sampling proportion in each group based onsquare root or logarithm, sampling method within group clustered.16%, 10% and 5% overall sampling ratio were usedto establish primary core collections. The results showed that a5∽10% sampling ratio was suitable for a largecollection.