Breeding an underutilized fruit crop: a long-term program for Hylocereus

Abstract

This review describes three decades of introduction, agro-technology development, breeding and selection of Hylocereus species, known as pitaya or dragon fruit, as an example of a holistic program aimed to develop the horticultural potential of a perennial underutilized fruit crop. Interspecific homoploid and interploid crosses and embryo rescue procedures produced improved hybrids, some of which have been released to farmers. Molecular tools and morphological and phenological comparisons between the parental species and the resulting hybrids provided valuable information on dominant/recessive traits and on genetic relationships that could be exploited for further hybridizations. In addition, Hylocereus were crossed with species of the closely related genus Selenicereus, producing valuable intergeneric hybrids. In situ chromosome doubling resulted in the production of autopolyploid lines, from which an understanding of the effect of increased ploidy on fruit traits and metabolomic profiles was obtained. Gamete-derived lines were produced, adding to our biobank homozygote lines that were subsequently used for further hybridization. Spontaneous chromosome doubling occurred in haploid gamete-derived Hylocereus monacanthus lines and in interspecific interploid Hylocereus megalanthus × H. undatus hybrids obtained from an embryo rescue procedure, resulting in plants with double the expected ploidy. Challenging technical problems were addressed by the development of protocols for DNA isolation, flow cytometry, in situ chromosome doubling, androgenesis, gynogenesis and embryo rescue following interspecific and interploidy crosses. Current research leading to the development of genomics and molecular tools, including a draft genome of H. undatus, is also presented. Perspectives for further development of Hylocereus species and hybrids are discussed.

Characterization of yellow pitahaya (Selenicereus megalanthus Haw.) genotypes under two productive systems in Colombia

“…The importance of the cultivation of S. megalanthus for their commercialization has allowed for the development of a wide variety of studies about the quality of the fruit, commercialization, nutritional composition, cultivation, phenology, organic fertilization, physical chemistry, genetics, postharvest management, morphology and production systems (Tel-Zur, 2022).…”

“…However, even today, it is difficult to clearly identify the species and varieties of dragon fruit, due to its high rate of inter-and intra-specific hybridization and the genotype-environment interaction that has led to some confusion at the national level taxonomic worldwide (Tel-Zur, 2022). The phenotypic and genetic variability in morphological characteristics associated with the plant such as height, width ribs of the cladode, distance between areoles, number of sprouts, length of the spines and sweetness, size and color of the fruit are the product of this natural hybridization process (Tel-Zur et al, 2011).…”

Pitaya as a New Alternative Crop for Iberian Peninsula: Biology and Edaphoclimatic Requirements

“…megalanthus ) is a tetraploid species, having 2 n = 4 x = 44 chromosomes. This evidences the genetic proximity between all pitayas and justifies the possibility of performing interspecific homoploid crosses (2 n × 2 n ) to obtain diploid hybrids [ 11 , 69 , 70 ].…”

“…Cactoideae subfamily comprises epiphytic, hemiepiphyte and climbing cacti, but the genera within this subfamily are poorly defined and there is not a consensus among taxonomists. Recent studies, based on molecular markers, have shown that genus Hylocereus (A. Berger) Britton and Rose, which includes most cultivated pitayas, should be grouped in the genus Selenicereus (A. Berger) Britton and Rose [ 20 ]; however, prestigious researchers specializing in pitaya genetics continue to distinguish the two genera separately [ 11 ]. This has negative implications, as identical plants are referred to with different scientific names, confusing readers (researchers, agronomists and farmers).…”

“…Production systems vary with production areas, from agroforestry systems in Latin America to greenhouse production in the USA (California) [ 8 , 9 ]. There has also been important progress in genetic improvement, mainly in Israel [ 10 , 11 ], but also in Brazil, United States and other countries. The introduction and growth of the area of pitaya cultivation in the Iberian Peninsula results, therefore, of the demand for new crops in this region of the globe and follows the world trend of expansion of crops whose fruit is associated with healthy diet.…”