Genetic Uniformity of the MSXJ papaya hybrid (Carica papaya L.) during Micropropagation

Objective. To analyze the genetic uniformity of the MSXJ papaya hybrid vitroplants, obtained via direct organogenesis. Design/methodology/approach. The MSXJ papaya hybrid presents quality characteristics for national and export markets. The in vitro plant tissue culture represents a tool for its multiplication and conservation, but somaclonal variation can decrease its genetic and agronomic uniformity. In order to analyze the genetic uniformity of this hybrid vitroplants, 10 ISSR primers were used in micropropagated vitroplants during nine subcultures. DNA extraction was carried out with the CTAB method. The data analysis was performed with the PopGene v 1.3.1 program. Results. Eighty five loci of 200 to 2000 bp were generated, with 37 polymorphic loci. In the cluster analysis, three groups were observed that separated subculture one, subcultures two through eight, and subculture nine; the Gst value of 0.87 indicated genetic uniformity up to subculture eight. Limitations/implications. Papaya is one of the most important tropical fruits worldwide; however it is necessary to have healthy and genetically uniform plants that guarantee their quality. In vitro propagation allows to produce healthy and uniform plants, but it is necessary to study their genetic uniformity during their micropropagation. Findings/conclusions. The in vitro multiplication of the MSXJ papaya hybrid allowed to regenerate vigorous plants in 30 days. Molecular profiles indicated that up to subculture eight plantlets were genetically uniform, so it is recommended not to carry out more than eight subcultures during micropropagation.Objective: To analyze the genetic uniformity of MSXJ hybrid papaya in vitro plants, obtained by direct organogenesis.Design/Methodology/Approach: The MSXJ papaya hybrid demonstrates quality characteristics for the national and exports market. In vitro culture of plant tissues represents a useful tool for their multiplication and conservation, but somaclonal variation can diminish their genetic and agronomic uniformity. In order to analyze the genetic uniformity of in vitro plants of this hybrid, ten ISSR primers were used for in vitro plants micropropagated during nine subcultures. DNA was extracted using the CTAB method. Data were analyzed using the program PopGene v 1.3.1.Results: Eighty-five loci of 200 to up to 2000 pb were generated, with 37 polymorphic loci. In the cluster analysis, three groups were observed which separate subculture one, subcultures two to eight, and subculture nine; the Gst value of 0.87 indicated genetic uniformity as far as subculture eight.Study Limitations/Implications: Papaya is one of the most important tropical fruits worldwide; however, these plants need to be healthy and genetically uniform to guarantee commercial success. In vitro propagation allows obtaining healthy and uniform plants, but it is necessary to study genetic uniformity during their micropropagation.Findings/Conclusions: The in vitro multiplication of the MSXJ papaya hybrid permitted the regeneration of vigorous plants in 30 d. Molecular profiles indicate that as far as subculture eight, there is genetic uniformity. As such, no more thaneight subcultures are recommended during micropropagation

Sex Identification of in vitro Plants of Carica papaya L. MSXJ Hybrid through Molecular Markers

Objective: To identify the sex in vitro plants of the MSXJ hybrid papaya (Carica papaya L.) obtained via somatic organogenesis, using molecular markers SCAR type. Design/methodology/approach: Plants of the MSXJ hybrid papaya with eight months of age and during the fruiting stage were collected at the municipality of Cotaxtla, Veracruz. They were superficially disinfected, with plenty of running water, detergent for 30 minutes, 70% alcohol was added for one minute, 30% commercial chlorine for another 30 minutes and rinsed with sterile distilled water. Subsequently the meristems were grown under a MS medium, and after 30 days a subculture was performed. The extraction of DNA was performed using the Doyle and Doyle method. The PCR was done by the Deputy et al. method, and initiators T1, T12 and W11 were used. Results: Initiator T1 was positive control. Initiators T12 and W11 allowed the amplification of fragments identifying hermaphrodite, female and male plants, while the T12 and W11 initiators were specific to hermaphrodite plants. Study limitations/implications: Papaya producers know the genus of plants three months after planting. Sexuality in papaya plants cannot be differentiated until the flowering step. Findings/conclusions: the implementation of molecular markers could facilitate large-scale plant selection, reducing costs, maintenance time and the elimination of plants with unwanted sex.Objective: To identify the sex of in vitro plants of papaya (Carica papaya L.) MSXJhybrid obtained via somatic organogenesis, through SCAR type molecular markers. Design/Methodology/Approach: Eight-month old MSXJ papaya hybrid plants in thefructification stage were collected in Cotaxtla, Veracruz, Mexico. They weresuperficially disinfected with abundant running water, detergent during 30 min, andthen alcohol at 70% was added for one minute, commercial chlorine at 30% for 30min, and they were rinsed with sterile distilled water; then the meristems werecultivated in MS medium and after 30 d a subculture was made. The DNA extractionwas made with the CTAB method, and the DNA PCR was done with the Deputy et al.(2002) method, and the primers T1, T12 and W11 were used.Results: The T1 primer was the positive control and the T12 and W11 primersallowed the amplification of fragments that identify hermaphrodite, feminine and maleplants, while the T12 and W11 primers were specific for hermaphrodite plants.Study Limitations/Implications: It is required to standardize the method for it to beinexpensive.Findings/Conclusions: The sexuality of papaya plants can be differentiated until thestage of flowering, which is why the implementation of molecular markers wouldfacilitate plant selection if it is implemented at a large scale. Costs, maintenance timeand elimination of plants of unwanted sex are reduced this way