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.
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.