ARS | Publication request: EVOLUTION OF CUPHEA SPP. DURING DOMESTICATION

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2005
Publication Date: July 23, 2005
Citation: Jaradat, A.A. 2005. Evolution of Cuphea spp. during domestication [abstract]. XVII International Botanical Congress Abstracts. p. 496.

Interpretive Summary: Cuphea lanceolata and Cuphea viscosissima were emphasized as candidates for domestication and for in-depth research because of their oil content and composition. The oil is of significant interest in lubricant and health product industries as a biodegradable replacement for petrochemical oils or as oil with new properties. The two species are inter-fertile, thus allowing for combining desired traits from both in new genotypes. PSR23, a genotype derived from a cross between the two species, was selected for its favorable agronomic and oil characteristics. However, indeterminacy, seed shattering and post-harvest dormancy of PSR23 constitute its domestication syndrome. We quantified the level of divergence between accessions of PSR23 and its wild parents for seed morphological and physiological traits as well as plant morphology and phenology. PSR23 showed marked reduction in diversity of seed and plant characters thus favoring characters which are better adapted to cultivation. In addition, the morphological and physiological gap between PSR23 and its wild parents is widening as indicated by consistent and gradual differences in the principal components' structure, and by smaller fractal dimension of seeds, capsules and mature plants. Six harvest-planting cycles resulted in (1) shifts in the magnitude of association among plant and seed morphological characters, (2) higher frequency of tall and more erect genotypes, (3) heavier and more circular seed with reduced post-harvest dormancy and (4) greater germination index, as compared with the wild progenitors. The information will aid geneticists and plant breeders in their quest to fully domesticate the new crop.

Technical Abstract: Cuphea, a semi-domesticated crop, is a potential source of oil suitable for industrial uses. Indeterminacy, seed shattering and post-harvest dormancy constitute its domestication syndrome. PSR23, a selection from a Cuphea viscosissima Jacq. x Cuphea lanceolata f. silenoides W.T. Aiton cross, was assessed for seed, capsule, and plant morphological and physiological characters. PSR23 germplasm produced during six consecutive years showed a reduced genetic diversity favoring characters better suited to cultivation. Morphological and physiological divergence of PSR23 from its wild progenitors increased as indicated by consistent and gradual differences in the principal components structure, and by smaller fractal dimensions of seeds, capsules and mature plants. Directional selection through agricultural practices increased the frequency of tall and more erect genotypes, heavier and more circular seed with reduced post-harvest dormancy and greater germination index as compared with the wild progenitors. Indehiscence and determinacy are critical to fully domesticate PSR23. Stabilizing selection will be needed to maintain the domesticated crop.