Fruit and seed attributes of plants derived from crossing between triploid Passionflower cytotypes.

Abstract

Triploid plants are usually sterile or produce non-viable seeds, but may produce fruits. This study examined the morphological and reproductive characteristics of triploid Passiflora cincinnata Masters, with a focus on fruit and seed production. Triploid plants were obtained through in vitro cultivation of the endosperm via somatic embryogenesis, whereas diploid plants were raised through seed germination. Diploid and triploid plants were confirmed by flow cytometry and cytogenetic analyses. Cross-pollination and self-pollination yielded, on average, 18 fruits per plant in the cytotype diploid, while triploids produced only 6 fruits. Diploid plants have more uniform fruits, while triploid plants showed variations in size. Seeds with malformations or absence of zygotic embryos and endosperm were observed in triploid cytotypes, while remaining below 1.5% in diploid cytotypes. It was observed that the highest germination rate of 80% occurred in seeds of the diploid cytotype, compared to 53.3% in triploids. The seedlings from the cross between diploid plants contained 3.29 pg of nuclear DNA and a chromosome number of 2n = 2x = 18, while the seedlings from the cross between triploid plants had progeny with 3.37 pg of nuclear DNA and variable chromosomes numbers, of 2n = 19 (2n + 1), 2n = 15 (2n - 3), and 2n = 16 (2n - 2) chromosomes confirming aneuploidy in the progeny. Stomatal analysis showed that diploid plants displayed the highest stomatal density, whereas triploid and aneuploid plants had the greatest length and width of stomata. The density and width of pavement epidermal cells varied among cytotypes. Meiotic disturbances in triploid plants cause phenotypic alterations in the progeny, resulting in delayed vegetative development, low vigor, non-uniform germination, and death during the juvenile phase. The genetic material of aneuploids is a resource for gene mapping, enabling the modification or production of new cultivars with economically relevant phenotypes.