Growth and survival of Prosopis africana provenances tested in Niger and related to rainfall gradients in the West African Sahel.

The understanding of the genetic diversity and structure of populations ofJatropha curcas in their postulated centre of origin will permit to identify genetic material useful for future improvement of the species. Although it is estimated that Mexico is the likely centre of origin and domestication of J. curcas, so far the "true" centre of origin still has to be found. A representative set of 175 accessions of J. curcas from nine central and southeastern Mexican states (Chiapas, Veracruz, Oaxaca, Michoacan, Morelos, Yucatan, Guerrero, Hidalgo and Puebla), including toxic, non-toxic, and contrasting protein and oil content genotypes was used for diversity analysis by AFLP markers. The results indicate that Mexico has a high genetic diversity of J. curcas; molecular analysis suggests population structuring in the different states where this species is spread. The germplasm from Chiapas, where contrasting protein and oil content genotypes were detected, showed the highest genetic diversity and clearly varies from the accessions from the other states. This is probably the most comprehensive study of diversity of germplasm of 3. curcas from Mexico, and together with previous reports on the genetic diversity, biochemistry, morphology and germplasm agronomics of J. curcas from Chiapas, suggest the likelihood that this area is the centre of origin for this species and that domestication took place in the states bordering the Gulf of Mexico, such as Veracruz, Hidalgo, Puebla and Yucatan, where genotypes with low or no phorbol ester content exist. (C) 2013 Elsevier Ltd. All rights reserved.

Genetic structure of Jatropha curcas L. in Mexico and probable centre of origin

• Variation in wood basic density and its correlation with tree growth were investigated at 13 years in a provenance/progeny test of Prosopis africana in Niger. The test included progeny from 256 trees sampled from 24 provenances in the Sahelian ecozone of Burkina Faso and Niger.


• Variation in wood density was significant due to provenances and families within provenances. Individual tree heritability was higher for wood density than for growth traits. Provenance means for wood density increased from the more humid to the drier parts of the sample region. Phenotypic correlations indicated that larger trees tended to have denser wood.


• Clines suggest that natural populations of P. africana from the drier parts of the sample region have the genetic capacity to produce denser wood, compared with populations from the more humid parts of the region. Correlations and heritability estimates suggest that selection of faster-growing trees may produce a small gain in wood volume but little (if any) gain in density in the subsequent generation. Multi-location provenance/tests are needed to confirm this tentative conclusion.

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Genetic variation in wood density and correlations with tree growth in Prosopis africana from Burkina Faso and Niger

Unusual physiological properties of the arid adapted tree legume prosopis and their applications in developing countries

Prosopis represents a valuable forest resource in arid and semiarid regions. Management of promising species requires information about genetic parameters, mainly the heritability (h(2)) of quantitative profitable traits. This parameter is traditionally estimated from progeny tests or half-sib analysis conducted in experimental stands. Such an approach estimates h(2) from the ratio of between-family/total phenotypic variance. These analyses are difficult to apply to natural populations of species with a long life cycle, overlapping generations, and a mixed mating system, without genealogical information. A promising alternative is the use of molecular marker information to infer relatedness between individuals and to estimate h(2) from the regression of phenotypic similarity on inferred relatedness. In the current study we compared h(2) of 13 quantitative traits estimated by these two methods in an experimental stand of P. alba, where genealogical information was available. We inferred pairwise relatedness by Ritland's method using six microsatellite loci. Relatedness and heritability estimates from molecular information were highly correlated to the values obtained from genealogical data. Although Ritland's method yields lower h(2) estimates and tends to overestimate genetic correlations between traits, this approach is useful to predict the expected relative gain of different quantitative traits under selection without genealogical information.

/pdf/consistency-between-marker-and-genealogy-based-heritability-q2y9uojiyp.pdf

Consistency between marker- and genealogy-based heritability estimates in an experimental stand of Prosopis alba (Leguminosae)

The section Algarobia of genus Prosopis involves important natural resources in arid and semiarid regions of the world. Their rationale use requires a better knowledge of their biology, genetics and mating system. There are contradictory information about their mating system. Some authors claim they are protogynous and obligate outcrosser. However, some evidence have been shown indicating that they might not be protogynous and that they might be somewhat self-fertile. The current paper analyses genetic structure and mating system parameters in populations of seven species of this section from South and North America based on isozyme data. In all species a significant homozygote excess was found in the offspring population but not in mother plant genotypes. Multilocus and mean single locus outcrossing rates (tm, ts) indicated that about 15% selfing can occur in the studied populations. The heterogeneity between pollen and ovule allele frequencies was low suggesting population structuration, in agreement with the estimates of correlation of tm within progeny (rt) and correlation of outcrossed paternity (rp). The difference of FIS estimates between offspring and mother plants suggest some selection favouring heterozygotes between seedling and adult stages.

/pdf/mating-system-parameters-in-species-of-genus-prosopis-hltu3yw56s.pdf

N Julio

Papers

Mating system parameters in species of genus Prosopis (Leguminosae).