International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.1, 30-43 http://ecoevopublisher.com/index.php/ijmec 31 adaptive role, adaptive mechanism of Central American origin, adaptive breeding and selection, regional adaptation case study, constraints on germplasm utilization, expansion of cultivation opportunities and future prospects. It aims to clarify how genetic variation promotes the successful cultivation of yellow pitaya in different regions and provide a scientific basis for future breeding and cultivation. 2 Origin and Domestication of Yellow Pitaya 2.1 Native distribution and domestication centers Yellow pitaya originated in tropical America. According to historical records, pitaya plants are native to southern Mexico and Central America, including tropical rainforests and dry forests in countries such as Nicaragua, Colombia, and Venezuela (Shah et al., 2023). These areas have high temperatures and moderate rainfall throughout the year, and the altitude ranges from a few meters to nearly 1,840 meters, which breeds rich wild germplasm resources of the genus Pitaya. Yellow pitaya, as a yellow-skinned and white-fleshed species in the genus Pitaya, is believed to have originated mainly in countries around the Andes Mountains in South America, such as Bolivia, Ecuador, Colombia, and Peru (Chen et al., 2023). In the place of origin, wild pitaya plants often grow as epiphytic vines on the edge of forests or in rock crevices, showing climbing, multi-branching characteristics and the ability to adapt to barrenness and drought. 2.2 Historical pathways of early cultivation and trade The domestication and cultivation of yellow pitaya has a relatively short history. After the Age of Discovery in the 16th century, European explorers first introduced pitaya from Central and South America to Asian colonies (Hernández and Salazar, 2012). According to literature reports, as early as the Shunzhi period of the Qing Dynasty (around 1645 AD), the Dutch had introduced Hylocereus serrata (a type of pitaya) to Taiwan as a garden ornamental plant. However, due to problems such as self-incompatibility of the strains introduced at that time, commercial production was not formed. In the mid-19th century, French missionaries brought pitaya to their colonies in Indochina (Vietnam, Laos, Cambodia), and pitaya began to take root in Southeast Asia. In the late 20th century, with the selection and spread of new strains, the planting area of pitaya in Asia expanded rapidly (Trindade et al., 2023). In particular, in the 1980s, Vietnam introduced new self-fertile red-fleshed pitaya varieties from Colombia and other places, and introduced these varieties to Taiwan in 1983, thus starting the process of pitaya industrialization in Taiwan. 2.3 Genetic consequences of domestication events Currently, the cultivated pitaya in the world mainly includes three cultivated populations: red-skinned white-fleshed species (Hylocereus undatus), red-skinned red-fleshed species (H. polyrhizus or H. costaricensis), and yellow-skinned white-fleshed species (S. megalanthus). Among them, H. undatus is native to Mexico and Central America, H. polyrhizus is native to Mexico and other places, and S. megalanthus is native to North and South American countries around the Andes Mountains (Alves et al., 2021). As the latter, yellow-skinned pitaya is mainly collected by local people for consumption in its natural state. It has not yet undergone a long process of human selection and domestication and is considered to be still in a "semi-domesticated" state. This is reflected in its cultivation characteristics. For example, the yellow-skinned pitaya still retains wild characteristics such as hard thorns on the skin and relatively concentrated flowering period, which need to be improved through breeding to adapt to modern agricultural production. 3 Germplasm Resources and Global Dissemination 3.1 Classification and characteristics of germplasm types The germplasm resources of yellow pitaya have significant diversity and regionality (Figure 1). Wild pitaya plants in Central and South America have rich species and intraspecific variation, including variations in morphological traits such as plant size, stem fleshiness, fruit color and flavor, as well as differences in adaptation to environmental factors (such as drought resistance and barrenness resistance). These wild resources are an important basis for improving cultivated varieties. In recent years, through field collection and introduction and preservation, research institutions in various countries have accumulated a certain scale of pitaya germplasm banks. For example, agricultural research units in Guangxi and Hainan, China have widely introduced dozens of
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