PT-school of Pure and Applied Sciences
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Browsing PT-school of Pure and Applied Sciences by Author "Jalemba, M.A."
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Item In-vitro colchiploidy in diploid purple passion plants targeting to increase the fruit size and pulp content(2014-08-13) Mureithi, James Mwangi; Jalemba, M.A.; Waturu, C.Purple passion (Passiflora edulis Sims f. edulis) is a diploid plant with 2n = 2x = 18 chromosomes. It belongs to the Passifloraceae family in which the genus Passiflora is ranked as the most important, having around 530 species mainly distributed throughout the tropical regions of the South America (Argentina, Brazil, Colombia, Ecuador, Peru, Venezuela) and to an increasing extent in the tropical African countries and subtropical Southeastern Asia, Australia and New Zealand. Purple passion fruit has great potential in the fresh and juice industry due to its sweet lucrative fruit flavour, excellent taste, pleasant aroma, high amounts of beta carotene, potassium and dietary fibre; thus an important fruit in the market worldwide. However, the yellow passion (P. edulis f.flavicarpa Degener) is gaining popularity over the purple in the juice industry due to its larger fruits that yield higher pulp. This study aims to generate autotetraploids of the purple passion plant in-vitro by doubling the number of chromosomes to 2n = 4x = 36, by treating with colchicine. Polyploids are known to express favourable traits such as larger fruit size, sturdiness, enhanced disease/pest resistance and stress tolerance, seedless or fewer seed production as well as increased biomass or product yields. Seeds of purple passion will be collected from ripe fruits, their embryos extracted and sterilised, then germinated in-vitro to provide clean source of explants. Hypocotyl segments shall be excised from the shoots of invitro grown seedlings then treated with three concentrations of colchicine at 12.5, 25, 37.5 ~M and a control. Upon shoot and root formation, the regenerated seedlings will be transplanted into buckets with soil and grown to maturity in a screen house. Generated polyploids will be identified by observing the number of chloroplasts on stomatal guard cells on the lower leaf epidermis and further selection of successful autotetraploids will be done by counting the number of chromosomes in the root apicals. Selected autotetraploids from all treatments will be grown to maturity and their ripened fruits analysed for their variance (ANO VA) to determine any significant morphological differences in weight (g), length (em), diameter (em), number of seeds (black and white), and amount of juice per fruit (ml) among the diploids and autotetraploids, tested by Tukey's test at 5% level using GENES software package (Cruz 2008). Improved traits in fruit size and pulp content of the autotetraploids will form a logical conclusion to this study