Examinando por Materia "Phenotype"

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Development and phenotypic characterization of a native Theobroma cacao L. germplasm bank from the Loreto region of the Peruvian Amazon: Implications for ex situ conservation and genetic improvement
(Frontiers Media S.A., 2025-06-16) Imán Correa, Sixto Alfredo; Samanamud, Angelo F.; Ramírez , José F.; Cobos, Marianela; Paredes, Cleydi; Castro, Juan C.
Introduction: The ex situ conservation and characterization of native Theobroma cacao L. genetic resources are critical for sustainable cacao production and breeding programs in the face of climate change and escalating disease pressures. This study aimed to establish and characterize a novel germplasm bank from the Loreto region of the Peruvian Amazon, a key center of cacao diversity. Methods: We collected 140 native cacao accessions across 15 river basins in eight provinces of the Loreto region. Accessions were propagated using optimized grafting techniques with IMC 67 rootstock. Phenotypic evaluation was conducted on 402 plants using 36 standardized descriptors (25 quantitative and 11 qualitative). Data analysis included multivariate analysis using Uniform Manifold Approximation and Projection (UMAP) and Shannon-Weaver diversity indices to assess morphological diversity patterns. Results: Grafting achieved 100% survival rate, establishing a comprehensive germplasm bank. Phenotypic characterization revealed exceptional morphological diversity, with quantitative traits exhibiting substantial variation, particularly in fruit characteristics (CV = 15.82–50.82%) and pod index (CV = 144.82%). Multivariate analysis identified five distinct phenotypic groups, with reproductive traits showing stronger differentiation than vegetative traits. Shannon-Weaver diversity indices highlighted high overall phenotypic diversity (H' ≈ 0.7), with seed longitudinal shape and fruit apex form displaying the highest trait-specific diversity (H' > 1.0). Conclusion: This comprehensive characterization establishes a foundation for future multiomics studies and advanced breeding strategies. The documented diversity offers opportunities to leverage CRISPR-Cas-based editing and omics technologies to develop climate-resilient, high-yielding cacao varieties with superior quality traits, contributing significantly to global cacao conservation and improvement programs.
Phenotypic characterization of wild Myrciaria dubia (Kunth) McVaugh ex situ germplasm bank for breeding, conservation, and sustainable development in the Peruvian Amazon
(Frontiers Media SA, 2025-08-07) Imán Correa, Sixto Alfredo; Samanamud Curto, Angelo Francisco; Ramírez, Juan F.; Cobos, Marianela; Castro, Juan C.
Introduction: Myrciaria dubia “camu-camu” is an economically important Amazonian fruit shrub known for its exceptionally high vitamin C content. Despite its commercial value, comprehensive phenotypic characterization of available genetic resources remains limited, hindering breeding programs and conservation strategies. This study aimed to characterize the phenotypic diversity of wild accessions maintained in a 36-year-old ex situ germplasm bank, one of the most comprehensive M. dubia collections globally, to provide baseline data for genetic improvement and conservation. Methods: We evaluated 43 wild accessions systematically collected from eight major hydrographic basins in the Loreto region using a stratified sampling approach to capture maximum ecological diversity and maintained in an ex situ germplasm bank established in 1988 at the National Institute of Agrarian Innovation in Loreto, Peru. Twenty-three quantitative and six qualitative morphological descriptors were assessed using standardized protocols specifically developed for M. dubia, emphasizing commercially important descriptors including fruit weight, pulp content, and seed characteristics. Statistical analyses encompassed univariate variability assessment, bivariate correlations, and multivariate classification through hierarchical clustering and principal component analysis. Results: Phenotypic characterization revealed moderate overall variability with coefficient of variation averaging 17.4%, with reproductive descriptors showing greater variation than vegetative traits. Fruit and seed descriptors exhibited the highest variability exceeding 20%, while qualitative descriptors showed limited diversity with Shannon Index of 0.823. Multivariate analysis identified four distinct phenetic groups with no significant correlation to geographic origin (Mantel test, p=0.4034). Principal component analysis revealed fruit-related descriptors as primary drivers of phenotypic differentiation, explaining 57.1% of observed variability. Three accessions from phenetic group 3 (PER1000416, PER1000423, and PER1000411) demonstrated superior trait combinations: fruit weight exceeding 13 g, pulp content above 75%, and reduced seed count below 2.5 seeds per fruit. Conclusion: The moderate phenotypic variability observed reflects the natural distribution patterns and limited domestication history of the species. This comprehensive characterization provides essential baseline data and a foundation for targeted breeding programs, conservation strategies, and sustainable production systems supporting development while preserving the genetic diversity in the Peruvian Amazon
Selection in guinea pigs: I. Estimation of phenotypic and genetic parameters for litter size and body weight get access arrow
(American Society of Animal Science, 1983-04-01) Quijandria, B.; Chauca Francia, Lilia Janine; Robison, O. W.
Data on 202 sires, 718 dams and 3,192 progeny from a selection experiment were used to estimate phenotypic and genetic parameters for litter size and body weight in guinea pigs. Effects of sex and parity were estimated. Heritability estimates were obtained from offspring-parent regression and from intraclass correlation of paternal and maternal half-sibs. Genetic and phenotypic correlations also were estimated. Parity effects were significant only for weight traits. Sex effects were significant for weights at several ages. Significant negative linear effects of number born alive were found for birth, weaning and 13-wk weights. Heritability estimates from daughter-dam regression were .10 ± .05, .06 ± .02 and .08 ± .02 for number born, number born alive and number weaned and .12 ± .03, -.13 ± .03 and .12 ± .02 for birth, weaning and 13-wk weights, respectively. Paternal half-sib heritability estimates were .02 ± .04, .10 ± .04 and .17 ± .05 for birth, weaning and 13-wk weights. Heritability values from components for maternal half-sibs were .30 ±.30, .16 ±.31 and .15 ± .31 for number born, number born alive and number weaned, respectively. Genetic correlations among weights at different ages were .24 to 1.2 and among litter size traits were .51 to .77. Genetic correlations between litter size traits and birth and weaning weights ranged from -.61 to -.97; whereas correlations of litter size traits with 13-wk weight were .31 to .39. Genetic parameters estimated from similarity among relatives agreed very well with realized heritabilities and genetic correlations obtained from selection.