morphological traits among papaya ( Caricapapaya ) accessions in Nigeria Fruits 67 173 187 Alonso, M. Alor, B. García, O. Moreno, Q. Teyer, S. Felipe, L. 2009 Caracterización de accesiones de papaya ( Caricapapaya L.) a través de marcadores AFLP en Cuba
In Mexico, Caricapapaya L. is cultivated in 19 states, with a harvested area of 16,684 ha, concentrated mainly in Veracruz (3196 ha), Colima (2850 ha), Oaxaca (2702 ha), Michoacan (2368 ha), and Guerrero (1124 ha) ( SIAP-SAGARPA, 2017 ). Despite
from a wide variety of biotic sources, including wood, straw, mixtures of dry and fresh plant material, and charred wood, can stimulate germination ( Brown and Van Staden, 1997 ). Papaya ( Caricapapaya ) seed germination is affected by many
Leaves normally represent the assimilating area of a plant and determine its photosynthesis and dry matter accumulation. Papaya ( Caricapapaya L.), a C 3 plant ( Marler et al., 1994 ), develops new leaves, flowers, and fruit continually, with 2
Papaya (Carica papaya L.) fruit flesh and seed growth, fruit respiration, sugar accumulation, and the activities of sucrose phosphate synthase (SPS), sucrose synthase (SS), and acid invertase (AI) were determined from anthesis for ≈150 days after anthesis (DAA), the full ripe stage. Sugar began to accumulate in the fruit flesh between 100 and 140 DAA, after seed maturation had occurred. SPS activity remained low throughout fruit development. The activity of SS was high 14 DAA and decreased to less than one-fourth within 56 DAA, then remained constant during the remainder of fruit development. AI activity was low in young fruit and began to increase 90 DAA and reached a peak more than 10-fold higher, 125 DAA, as sugar accumulated in the flesh. Results suggest that SS and AI are two major enzymes that may determine papaya fruit sink strength in the early and late fruit development phases, respectively. AI activity paralleled sugar accumulation and may be involved in phloem sugar unloading.
Populations of wild Carica papaya, previously designated as Carica peltata, were sampled from its native range on the Caribbean coast of Central America (Mexico, Belize, Guatemala, Honduras) and cultivated Carica papaya from both Central and South America were examined for isozyme variability. Thirteen loci from nine enzyme systems (Pgm, Pgi, Idh, Mdh, 6Pgd, Ugpp, Skdh, Aco, Tpi) were scored for all populations. Ten loci were polymorphic and a total of 31 alleles were detected. Isozyme genotypes as determined through segregation analysis were used in the genetic interpretation for eight loci and 18 alleles while six additional loci and 13 alleles were postulated on the basis of phenotypic variation found throughout the species. Nei's genetic identity, I, for both cultivated and wild Carica papaya was >0.9, which is consistent with conspecific populations. Wild papaya populations from different geographic areas appear more related to one another than to domesticates in the same geographic region.
Interspecific hybridizations were attempted between papaya (Carica papaya L.) and six Carica taxa, including C. monoica Desf., C. parviflora (A. DC.) Solms, C. pubescens Lenne et Koch, C. quercifolia (St. Hil.) Hieron., stipulata Badillo, and C. × heilbornii Badillo nm. pentagona (Heilborn). Prezygotic barriers were minimal; pollen tubes of wild species freely penetrated into the seed cavity of papaya, and papaya pollen tubes were similarly unhindered in reciprocal pollinations on C. pubescens. Postzygotic barriers were formidable due to ovule abortion and endosperm failure. However, dissection of more than 150 C. papaya fruits 90 to 180 days after interspecific pollination yielded at least a few hybrid embryos of each species combination. All crosses in which C. papaya was the male parent failed, with the exception of C. pubescens × C. papaya, which succeeded only after young ovules were cultured 30 to 45 days after pollination. Multiple embryos were common in all successful crosses, and these were shown to be of zygotic origin by analyses of isocitrate dehydrogenase, malate dehydrogenase, and phosphoglucomutase isozymes in parental and hybrid tissues. Hybrids successfully recovered from in vitro cultures included C. papaya × C. pubescens and reciprocal, C. papaya × C. quercifolia, and C. papaya × C. stipulata.
The occurrence of intra-ovarian ovaries in certain strains of Carica papaya L. is not uncommon. Approximately 150 hermaphroditic and 25 female ovaries from a hybrid progeny contained internal ovaries in stages of development ranging from thread-like appendages to round or elongated pistils of various sizes and shapes. A few were large enough to fill the entire seed cavity of the primary fruit and possessed their own cavities with non-viable seeds.
Internal ovaries originate either from stimulated growth of rudimentary pistillate structures extending from the central axis of the receptacle or from placentae in positions normally occupied by ovules. The placenta may be in its normal parietal position or a single strand may become free, extended from the base of the primary ovary and support a mal-shaped secondary ovary as well as ovules. The occurrence of internal ovaries supports theories proposed by other investigators on the evolution of floral morphology in the papaya.
An efficient protocol has been developed for the in vitro multiplication of papaya (Carica papaya L.) through somatic embryogenesis utilizing immature zgotic embryos. Somatic embryos were initiated on MS basel media supplemented with 5 mg·liter–1 2,4-D, 400 mg·liter–1 glutamine, and 6% sucrose. After culturing for 2 months, 65% of the explants became highly embryogenic. Each explant produced 50 to 80 embryos in 4 months on culture induction medium. Frequency of embryogenesis was increased (75 to 150 somatic embryos on 80% explants) upon supplementing medium with 4% maltose as a carbon source and 100 mg·liter–1 L-asparagine. The embryogenic callus appeared yellow and embryos at different stages of development were well-organized. On regular subculturing, these cultures continued to produce secondary embryos. Following their transfer to the hormone-free medium supplemented with 4% maltose, these embryos germinated. The somatic embryogenesis system is rapid, repetitive, and highly proliferative. Thus, this system may have a potential use in the development of synthetic seed and transgenic papaya plants. Details of important factors affecting somatic embryogenesis will be discussed.
Isozyme markers for glutamate oxaloacetate transaminase (GOT), superoxide dismutase (SOD), peroxidase (PER), and malate dehydrogenase (MDH) were identified for Carica papaya L. and the related but sexually incompatible C. cauliflora Jacq. These markers were used to determine the nature of somatic embryos derived from papaya ovules cultured on modified Murashige and Skoog (MS) medium 65 days after controlled pollination with C. cauliflora. Zymograms of plantlets from somatic embryos contained bands specific to either C. papaya or C. cauliflora (PER, GOT) and a unique band not present in the zymogram of either species (PER). Zymograms of somatic embryo-derived plantlets were distinctively different from those of either of the Carica species for all the enzyme systems examined. Evidence from isozyme markers indicates that somatic embryos produced from cultured papaya ovules following pollination with C. cauliflora may be hybrids. The isozyme banding patterns of 60 plantlets derived from somatic embryos from the same ovule were very uniform and suggest genetic uniformity among the regenerated plantlets.