Deployment Of Germplasm Research Articles

Molecular Characterization of Okra Genotypes Through RAPD and SSR Markers

Okra (Abelmoschus esculentus L.) is an important nutritious vegetable. Despite its high economic and industrial value, very little attention has been paid to assess genetic diversity of okra at molecular level. For effective conservation and proper deployment of germplasm, a study on genetic diversity analysis for fiber quality traits of okra germplasm was conducted with Random Amplified Polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers. Random Amplified Polymorphic DNA as well as simple sequence repeat markers were utilized to evaluate the genetic diversity among ten genotypes viz., GAO 5, AOL 12–55, AOL 10–22, AOL 13–73, AOL 13–75, AOL 13–88, AOL 13–90, Parbhanikranti, Pusasawani and wild type. A set of 15 RAPD primers were tested, total of 153 RAPD scorable fragments were produced of which all alleles were observed to be polymorphic. PIC values ranged from 0.77 to 0.92 with an average value of 0.84. The genotypes were broadly divided into two clusters. Cluster II included only wild type genotype. Sub cluster A1 comprised of genotype GAO 5. For SSR all 15 primers showed amplification and produced a total of 31 bands. The genetic distance (GD) among the okra genotypes ranged from 0.18 to 0.60. The highest GD (0.60) was detected between GAO 5 and Wild type, while the lowest GD (0.18) was observed between AOL 13–73 and AOL 13–88. The average observed mean heterozygosity was 0.60 and observed mean percentage of polymorphic loci was 67%. The diversity obtained could be exploited in the program of selection and varietal improvement of okra.

Restoration of Vanuatu sandalwood (Santalum austrocaledonicum) through participatory domestication

ABSTRACT Sandalwood (Santalum austrocaledonicum) is a fragrant tree of cultural and commercial importance in Vanuatu. The trade in its wild products has long provided income to landowners on remote islands. Due to unmanaged harvesting, however, wild sources of sandalwood in Vanuatu have declined in recent years. Domestication of the species and deployment of improved germplasm through smallholders can facilitate its restoration through circa situm plantings. Recognising the need to transition from wild harvest, landowners have commenced planting the species in home gardens and using it to enrich agricultural fallows and natural vegetation. Improvement of sandalwood through domestication has the potential to increase tree productivity, heartwood volumes and heartwood oil quality. This can enhance income and livelihood benefits associated with smallholder-planted sandalwood in Vanuatu. This paper outlines a strategy for participatory domestication to ensure that improved sandalwood germplasm is available for domestic sandalwood growers. The amount of the oil-bearing heartwood determines the commercial value of individual trees, which is linked to growth rates, heartwood oil concentration and chemical composition. There is substantial tree-to-tree and provenance-based variation in all these characteristics on which to base its domestication. The domestication strategy has been developed with consideration of the resources and capacities of stakeholders in Vanuatu. It is based on conventional approaches to plant improvement and the engagement of landowners to enhance germplasm deployment and manage institutional and environmental risk. The current breeding population comprises a grafted clonal archive of 39 genotypes selected from more than 250 wild trees sampled throughout the country. These genotypes were selected for their elevated levels of key oil components α- and β-santalol across seven island provenances. This breeding population has been deployed successfully as small clonal seed orchards on seven islands (Santo, Pentecost, Malekula, Ambrym, Epi, Efate and Tanna) to provide improved seed where it is needed most. The genetic base of established orchards will be expanded by introducing new selections from planted and wild populations in a ‘rolling front’ breeding strategy, as described in this paper. Families in the breeding population will be tested in progeny trials on participating islands to assess their genetic performance and retention in seed orchards, with later conversion to seedling seed orchards. The participatory approach to domestication and the deployment of germplasm provides a sound genetic foundation for landowner-driven sandalwood restoration in Vanuatu.

Multigenerational migration of fall armyworm, a pest insect

AbstractMultigenerational insect migration commonly expands poleward, but meteorological influences are not clearly understood. We coupled biological and physical processes for the agricultural and invasive pest Spodoptera frugiperda (fall armyworm), by modeling its seasonal migration, and comparing simulated migrations to observed captures, and population genetic markers, at a continental scale. Simulations corroborated the spatial distribution and mixing of Texas and Florida source populations defined by genetic haplotypes. Positive relationships were found between first weeks of simulated and observed immigration, and between genetic and simulated metrics. The capacity to project biotic‐, migratory‐, and meteorology‐induced shifts in insect distributions will aid strategic implementation of crop protection measures and economic analyses of host‐resistant germplasm deployment in response to a warming climate.

Assessment of genetic diversity among okra genotypes using SSR markers

Okra (Abelmoschus esculentus) is an important nutritious vegetable. Despite its high economic and industrial value, very little attention has been paid to assess genetic diversity of okra at molecular level. For effective conservation and proper deployment of germplasm, a study on diversity analysis of okra germplasm was conducted with DNA markers. Microsatellite/Simple sequence repeat (SSR) markers were utilized to evaluate the genetic diversity among 96 accessions of Abelmoschus, of which 92 accessions were of A. esculentus and one accession each of A. tuberculatus, A. moschatus, A. moschatus subspecies tuberosus and A. manihot. A set of 40 SSR primers were tested, of which 30 primers gave reproducible amplification which were used further for diversity analysis. With a mean of 7.1 bands per SSR, DNA amplification with 30 SSRs generated a total 213 bands, of which 60.66 % were recorded polymorphic. Polymorphic information content ranged between 0.11 and 0.80 with an average of 0.52, indicating that the majority of primers were informative. The Jaccard’s coefficient ranged from 0.107 to 0.969. The UPGMA analysis grouped Abelmoschus genotypes into three main clusters at a cut-off of 0.20. Results of present study revealed that sufficient variation exists among the studied accessions and GAO-5 which was found highly diverse can be exploited for okra improvement. The outcome of present research would assist to make use of Ablemoschus germplasm for okra breeding.

Visualising the environmental preferences of Pinus tecunumanii populations

A network of 92 pedigreed ex situ conservation plantings of Pinus tecunumanii, established as replicated progeny within provenance trials, is used to present a principal components-based analysis that illustrates the climatic preferences of 23 populations from the species’ native range. This meta-analysis quantifies changes in the relative productivity, assessed as individual-tree volume, of populations across climatic gradients and associates the preference of a population with increased volume production along the climatic gradient. Clustering and ordination on the matrix containing estimates of change in productivity for each population summarise differentials in productivity associated with climatic gradients. The preference of populations along principal components therefore reflects the adaptive profiles of populations, which may be used with breeding-value estimates from routine genetic evaluations to assist with the development of deployment populations targeting different environments. As well, the approach may be used to test whether the preference of a population, estimated as population loadings for growth differentials, is affected by the climate in the native range of the population. This relationship may be interpreted as an estimate of how much local climate shapes the adaptive profiles of populations. The amount and seasonality of precipitation most clearly differentiate the adaptive profiles of populations, with less variation in the population responses explained by temperature differentiation. As expected from type-B correlation estimates, most populations exhibited small changes in relative productivity across climatic gradients. However, patterns of similarities in adaptive profiles among populations were evident using spatial orientation to display population responses to the climatic variables experienced in the provenance trials. Clustering and ordination of population responses derived from empirical data served to identify populations that responded positively or negatively to climatic variables; this information may help guide conservation genetics efforts, direct the deployment of germplasm, or identify seed sources that are sensitive to changes in climatic variables. Linking response patterns to the climatic data from the native range of each population indicated little effect of local climate shaping adaptive profiles.

Screening Corymbia populations for resistance to Puccinia psidii

The exotic rust pathogen Puccinia psidii is now widespread along the east coast of Australia from temperate Victoria to tropical far north Queensland, with a current host range exceeding 200 species from 37 myrtaceous genera. To determine the threat P. psidii poses to plantation and native eucalypts, artificial inoculation was used to screen germplasm of spotted gum (Corymbia spp.) for resistance to the biotype of P. psidii that has become established in Australia. The objective was to characterize resistance to P. psidii within the Corymbia species complex so that management strategies for the deployment of germplasm from existing breeding programmes of these spotted gum species could be developed. Symptom development initiated 7 days after inoculation, with resistant and susceptible seedlings identified within all species, provenances and families. Inter‐ and intraspecific variability in rust resistance was observed among spotted gum species. There was no apparent relationship between climatic conditions at the provenance origin and disease resistance. The heritability estimates for all assessments are moderate to high and indicate a significant level of additive genetic variance for rust resistance within the populations. The results of this study clearly identify potential to select for resistance at the family level within the tested populations. While the potential for P. psidii to detrimentally impact upon Corymbia in the nursery and in young plantations was demonstrated, estimations of the heritability of resistance suggest that efforts to enhance this trait through breeding have reasonable prospects for success.

Classifying genotype by environment interactions for targeted germplasm deployment with a focus on Eucalyptus

A novel methodology for describing genotype by environment interactions estimated from multi-environment field trials is described and an empirical example using an extensive trial network of eucalypts is presented. The network of experiments containing 65 eucalypts was established in 38 replicated field trials across the tropics and subtropics of eastern Australia, with a selection of well-tested species used to provide a more detailed examination of productivity differentials across environmental gradients. By focusing on changes in species’ productivity across environmental gradients, the results are applicable for all species established across the range of environments evaluated in the trial network and simultaneously classify species and environments so that results may be applied across the landscape. The methodology developed was able to explain most (93 %) of the variation in the selected species relative changes in productivity across the various environmental variables examined. Responses were primarily regulated by changes in variables related to water availability and secondarily by temperature related variables. Clustering and ordination can identify groups of species with similar physiological responses to environment and may also guide the parameterisation and calibration of process based models of plant growth. Ordination was particularly useful in the identification of species with distinct environmental response patterns that would be useful as probes for extracting more information from future trials.

Genotype–environment interaction in Gliricidia sepium: Phenotypic stability of provenances for leaf biomass yield

Limited multi-location testing has been undertaken in Gliricidia sepium and other agroforestry species compared to field crops and plantation forest tree species. Consequently, information on the stability of the various provenances (accessions) of this species is very limited, reducing the efficiency of germplasm deployment. In this study, genotype–environment interaction and phenotypic stability of 14 accessions were investigated for dry matter (DM) leaf biomass yield across five diverse sites in the tropics (Indonesia and Nigeria) and subtropics (Australia, Malawi and Zambia) using nonparametric methods. Results indicated that genotype–environment interaction is present and that some accessions were unstable across these diverse environments implying that blanket recommendation for germplasm deployment may not be efficient. The most unstable accessions for leaf biomass production in this study include the widely used Retalhuleu provenance, which although highly productive, appeared to be better suited to tropical wetter environments. The Belen Rivas and Monterrico provenances were found to combine high phenotypic stability and high DM leaf biomass yield across these diverse sites. Germplasm of these seed sources may be deployed in previously untested sites with perhaps, predictable DM leaf yields. Where further breeding and selection is envisaged, the results of this study could also be used to make selections and constitute breeding populations for either specific environments (Retalhuleu) or for diverse environments (Belen Rivas and Monterrico).

Characterizing multiple linkages between individual diseases, crop health syndromes, germplasm deployment, and rice production situations in India

Five groups of crop health syndromes, four production situations, and three patterns of germplasm deployment were identified and characterized from a data set consisting of information from 129 Indian districts, which were surveyed in 2005 as part of the Production-Oriented Surveys conducted by the Directorate of Rice Research of the Indian Council of Agricultural Research. ANOVAs and MANOVAs indicated that these groupings from hierarchical cluster analyses correspond to clearly different levels of disease and animal pest injuries (crop health syndromes): of crop rotation, crop management, agricultural resources, and inputs (production situations); and of deployment of traditional, high yielding, or hybrid plant material (patterns of germplasm deployment). Correspondence analysis and discriminant analyses further indicated that crop health syndromes, and their change, are strongly associated with production situations, and patterns of germplasm deployment. A few specific hypotheses were tested, indicating that false smut is statistically associated with the involvement of hybrid rice in patterns of germplasm deployment. This highlights the need for research on the biology and the epidemiology of this disease in order to develop suitable management tools. Importantly, this work shows that national surveys, such as the Production-Oriented Surveys conducted by the Directorate of Rice Research, generate extremely valuable information to guide research and development through the characterization of production environments, contexts, and crop health responses, in times of unprecedented agricultural change. This work concurs with earlier results obtained at the field level, and thus opens important methodological questions regarding the up- and down-scaling of information between different scales (e.g., field, district). We propose that our ability to predict emerging diseases and crop health syndromes in the face of global and climate change will necessarily entail our ability to link different scales, where a range of different processes, biological and socio-economic, take place.

Biotechnological efforts for preserving and enhancing temperate hardwood tree biodiversity, health, and productivity

Hardwood tree species in forest, plantation, and urban environments (temperate regions of the world) are important biological resources that play a significant role in the economy and the ecology of terrestrial ecosystems, and they have aesthetic and spiritual value. Because of these many values of hardwood tree species, preserving forest tree biodiversity through the use of biotechnological approaches should be an integral component in any forestry program in addition to large-scale ecologically sustainable forest management and preservation of the urban forest environment. Biotechnological tools are available for conserving tree species as well as genetic characterization that will be needed for deployment of germplasm through restoration activities. This review concentrates on the biotechnological tools available for conserving, characterizing, evaluating, and enhancing hardwood forest tree biodiversity. We focus mainly on species grown for lumber and wood products, not species grown mainly for fiber (pulp and paper production). We also present a brief summary of the importance of non-wood forest products from temperate hardwood tree species (a research area that needs further development using biotechnological techniques) and a few case studies for preserving forest tree biodiversity.

Intellectual Property Protection for Plant Varieties in the 21st Century

Most genetic gains in U.S. maize (Zea mays L.) breeding come from pedigree breeding compared to more predictable backcrossing strategies. Historically, breeding access to proprietary maize germplasm was limited by trade secrets and heterotic group assignation. Advances in marker technologies, doubled haploidy and off‐season nurseries have revolutionized the speed and efficiency of germplasm access and utilization. Immediate access and facilitated deployment of germplasm that is already widely used in cultivation reduces the effective level of intellectual property protection (IPP) that was previously in effect by virtue of plant variety protection (PVP). Consequences of reduced IPP include yet further development of hybrids that more closely resemble existing widely used varieties and reduced incentives for the private sector to broaden the adapted germplasm base from the introduction of exotic germplasm. Breeders worldwide should have the choice of using utility patents and/or a new form of PVP that includes a revised breeder exemption. These changes will promote investments in crop improvement, together with additional benefit sharing via royalty flows from the use of exotic and underutilized germplasm, providing broader social benefits. Regular surveys of genetic diversity deployed on farms should also be undertaken because they represent an important component of national and global food security.

Tree domestication in tropical agroforestry

We execute tree ‘domestication’ as a farmer-driven and market-led process, which matches the intraspecific diversity of locally important trees to the needs of subsistence farmers, product markets, and agricultural environments. We propose that the products of such domesticated trees are called Agroforestry Tree Products (AFTPs) to distinguish them from the extractive tree resources commonly referred to as non-timber forest products (NTFPs). The steps of such a domestication process are: selection of priority species based on their expected products or services; definition of an appropriate domestication strategy considering the farmer-, market-, and landscape needs; sourcing, documentation and deployment of germplasm (seed, seedlings or clonal material); and tree improvement research (tree breeding or cultivar selection pathways). The research phase may involve research institutions on their own or in participatory mode with the stakeholders such as farmers or communities. Working directly with the end-users is advantageous towards economic, social and environmental goals, especially in developing countries. Two case studies (Prunus africana and Dacryodes edulis) are presented to highlight the approaches used for medicinal and fruit-producing species. Issues for future development include the expansion of the program to a wider range of species and their products and the strengthening of the links between product commercialization and domestication. It is important to involve the food industry in this process, while protecting the intellectual property rights of farmers to their germplasm.

Simulation Models for Predicting Durability of Insect-resistant Germ Plasm: Hessian Fly (Diptera: Cecidomyiidae)-resistant Winter Wheat

In an attempt to determine what strategies of resistant germ plasm deployment would most successfully inhibit Hessian fly, Mayetiola destructor (Say), adaptation to wheat resistance factors while offering significant crop protection, a computer simulation model was developed to mimic ecological/genetic interactions between Hessian fly populations and resistant winter wheat. Durability of the following resistant germ plasm deployment strategies was examined: 1) sequential release of two pure cultivars, each with a single resistance factor, 2) release of a random spatial mixture of these two cultivars, 3) release of a pure cultivar in which both resistance factors were present in each plant (pyramided), and 4) modification of each of the above deployment strategies by addition of totally susceptible wheat to the system. Effects of temporal and spatial characteristics of the mixtures were also explored. Interpolating a pyramided resistant cultivar with some totally susceptible plants offers the highest relative durability in most cases, and is predicted to last >400 fly generations under some conditions.