Image cytometric measurement of nuclear DNA content in pepper (Capsicum annuum L.) / Determinação do conteúdo de DNA em pimentão (Capsicum annuum L.) por citometria de imagem




Capsicum genus is one of the most important members of the Solanaceae family with high economic value. Out of 25 known species, five are extensively cultivated. Capsicum annuum is the most important commercially by its agronomic value as spice. In despite of this importance, the nuclear DNA content of C. annuum is still uncertain with values from the literature ranging from 5.52 to 10.80 pg. In face of the fast development of digital image technologies in cytometry, this study proposes the utilization of these resources to reevaluate the genomic size in C. annuum. The specific objectives were: (i) to determine the reliability parameters for image cytometry analysis by performing tests of equipment stability, linearity and uniformity of nuclei integrated optical density; (ii) to apply that parameters in analysis of erythrocytes nuclei from Gallus domesticus Leghorn (male and female); and (iii) to develop image cytomery methodologies for determination of the nuclear DNA content of pepper (C. annuum L. Fortuna Super ). Hen and rooster blood samples were prepared by using the method of smear preparation. The slides were stained with Feulgen reaction and they were used to perform the quality control procedures and integrated optical density measurements. Root tips of C. annuum were fixed, stained with Feulgen reaction and squashed on a microscope slide. Once the parameters of the reliability for performing image cytometry were established, the application of those standardizations in the chicken red blood cells suggested that this technique allows identification of differences in the nuclear DNA content between rooster and hen. Analysis of variance demonstrated that the 4.32% difference obtained was significant and it was attributed to sexual chromosomes heteromorfism. C. annuum analyses allowed the calculation of integrated optical density values, and they were in iccordance with the international standards for DNA image cytometry. The 2C DNA value for C. annuum Fortuna Super , using Pisum sativum as the internal standard, was 8.10 pg. This data differs in 2% from the previously obtained by flow cytometry for the same plant population. Besides, the value obtained in this study differs in16% and 28% from those 2C values previously published by image cytometry and in 7% and 32% for flow cytometry. These results include information about C. annuum genome that can be useful in breeding programs, genome sequencing projects and for comparative studies of genome evolution.


genetica vegetal image cytometry capsicum annuum dna quantification quantificação de dna citometria de imagem capsicum annuum green pepper pimentão

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