Seed Structural Variability and Germination Capacity in Passiflora edulis Sims f. edulis

Purple passion fruit, Passiflora edulis Sims f. edulis, is an important semi-perennial, fruit bearing vine originating in South America that produces a commercial tropical juice pulp for international and national consumption. Within the round purple passion fruit are a large number of membranous seed sacs each containing individual seeds. Little is known about the seed anatomy of the commercial passion fruit, differences between wild collected and commercial types, and its effect on seedling germination. Therefore, our main objective for this study was to analyze the seed anatomy variability of different germplasm as well as the effect on viability and germination of the seeds of this species. Germplasm was evaluated from three sources: (1) commercial cultivars grown in current production areas, (2) genebank accession from the national seed bank, and (3) landraces collected across different high and mid-elevation sites of the Andean region. A total of 12 morphometric descriptors related to seed anatomy were evaluated on the 56 genotypes, of which three were most informative: Angle to the vertex which is related to the shape of the seed, the thickness of the tegument and the horizontal length; separating the seed according to its source of origin. Germination was found to be positively correlated with the number (r = 0.789) and depth (r = 0.854) of seed pitting. Seeds of the commercial cultivars had more seed pits and higher germination compared to seeds of landraces or genebank accessions showing a possible effect of domestication on the crop. Interestingly, passion fruits often germinate during the rainy season as escaped or wild seedlings especially in the disturbed landscapes of coffee plantations, so some dormancy is needed but faster germination is needed for intensive cultivation. Harnessing passion fruit diversity would be useful as the semi-domesticated landraces have valuable adaptation characteristics to combine with rapid germination selected in the commercial cultivars. The variability of seed pitting with cultivars more pitted than landraces possibly resulting in faster germination may indicate that purple passion fruit is still undergoing a process of selection and domestication for this trait

Morphological and Agronomic Variability among Cultivars, Landraces, and Genebank Accessions of Purple Passion Fruit, Passiflora edulis f. edulis

Global demand for juice of the purple passion fruit, Passiflora edulis f. edulis, is growing, making it a promising species for farmers to grow in the highland tropics, to which it is adapted. However, research centers and private companies have done little to produce new high-yielding varieties. The objective of the present study, therefore, was to evaluate the agronomic and morphological characteristics of 50 passion fruit genotypes across two different elevations and agro-ecological sites as a base for germplasm enhancement. Three groups of genotypes were commercial cultivars (8 genotypes), genebank accessions (8), and landraces (34) collected from throughout the highlands of Colombia. The locations were at 1800 m above sea level (masl) (Pasca), in a place where cultivation of passion fruits is common; and at 2500 masl (Susacón), at a higher elevation site compared with most commercial plantings equal to a new agroecology for cultivation of the crop. Results indicated that the mid-elevation site produced higher yields (kg fruit/plant) than the high elevation site, although some landraces were highly productive there. Commercial cultivar and genebank accessions clustered together in a principal component analysis (PCA); while landraces showed high levels of variation in the trait descriptors with five different clusters. Therefore, landraces of purple passion fruit contained greater genetic diversity than commercial cultivars or the genebank, and breeding programs for the crop should use landraces to increase diversity of varieties available to producers and to further expand the crop to new regions, at higher elevations, or with different agro-ecologies

Estudio de la diversidad citogenética de Physalis peruviana L. (Solanaceae)

municipios de Villa de Leyva (Boyacá, Colombia), La Calera y Choachí (Cundinamarca, Colombia) y dos cultivados, uno de ellos nativo, el ecotipo Colombia distribuido en el municipio de Subachoque (Cundinamarca) y uno foráneo, procedente de Kenia, cultivado en el municipio de Paipa (Cundinamarca). Ápices radicales obtenidos a partir de semillas y de hojas en medios de cultivo in vitro enriquecidos con auxinas se emplearon para estandarizar el protocolo de obtención de cromosomas, con las diferentes técnicas de pretratamiento, fijación, hidrólisis y montaje de las muestras. Adicionalmente se evaluó la duración del ciclo celular para establecer la hora mitótica. Se encontró variabilidad genética entre los ecotipos evaluados. Los ecotipos silvestres presentaron una dotación cromosómica 2n=24, el ecotipo Colombia 2n=32 y el ecotipo Kenia 2n=48. Los ecotipos exhibieron también variación en las características morfológicas y anatómicas, que de acuerdo a la literatura, son un reflejo del nivel de ploidía, como altura, área foliar, número de estomas/mm', número de cloroplastos en las células guarda de los estomas, diámetro de frutos, semillas y contenido de masa seca

Estudio citogenético en Physalis peruviana l. “Uchuva” (Solanaceae)

En la presente investigación se estudian las características citogenéticas de cinco ecotipos de Physalis peruviana, tres silvestres distribuidos en Boyacá y Cundinamarca y dos ecotipos cultivados, uno nativo el ecotipo “Colombia”  distribuido en Cundinamarca y un ecotipo foráneo, procedente de Kenia, que se cultiva actualmente en nuestro país en el municipio de Paipa (Cundinamarca). Los resultados citogenéticos se obtienen luego de la estandarización del protocolo de obtención de ápices radicales a partir de semillas y hojas, empleando medios de cultivo in vitro. Se estandarizó el protocolo de obtención de cromosomas, empleando diferentes técnicas de pretratamiento, fijación, hidrólisis y montaje de las muestras, adicionalmente se evaluó la duración del ciclo celular para establecer la hora mitótica. Los resultados de la aplicación de estas técnicas, muestran una amplia variabilidad en la dotación cromosómica de las poblaciones estudiadas. Adicionalmente se evaluaron características morfológicas y anatómicas (Altura de las plantas, área foliar, número de estomas/mm2, número de cloroplastos en las células guarda de los estomas, diámetro de los frutos y semillas y contenido de masa seca) para confrontarlas con los datos citogenéticos. Sé evalúo la acción de la colchicina, para inducir la poliploidización en esta especie, para ello se eligieron frutos del ecotipo “Colombia” con un alto contenido de azúcares y sus semillas se cultivaron in vitro con el inhibidor mitótico, obteniéndose un diploide directo de este ecotipo. Se recomendó hacer un seguimiento de este material, para evaluar esta técnica dentro del programa de fitomejoramiento