Plant Gene and Trait 2024, Vol.15, No.6, 275-284 http://genbreedpublisher.com/index.php/pgt 276 National Agricultural Biodiversity Center, as well as those in Tanzania and Burkina Faso) in preserving genetic diversity, and proposes measures like on-farm conservation programs and core sample distribution to enhance local adaptability and resilience. Using examples from Hawaii and New Guinea, it explores the economic and cultural impacts of sweet potato genetic diversity, aiming to provide a theoretical basis and practical guidance for the effective conservation and sustainable utilization of global sweet potato germplasm resources. 2 Historical Overview of Sweet Potato Domestication 2.1 The origin and domestication process of sweet potato The domestication of sweet potato (Ipomoea batatas) is a complex process that has intrigued researchers for decades. The origins of this hexaploid species have been debated, with hypotheses suggesting either an autopolyploid origin from the diploid I. trifida or an allopolyploid origin involving genomes of I. trifida and I. triloba. Recent molecular genetic data, however, support an autopolyploid origin of sweet potato from an ancestor shared with I. trifida, which might be similar to currently observed tetraploid wild Ipomoea accessions. This suggests that cultivated I. batatas evolved from at least two distinct autopolyploidization events in polymorphic wild populations of a single progenitor species (Roullier et al., 2013). Additionally, cytogenetic studies have reinforced the close relationship between I. trifida and I. batatas, indicating that I. trifida might be the progenitor of I. batatas (Srisuwan et al., 2006). 2.2 Global distribution of sweet potato germplasm resources Sweet potato is now cultivated globally, with significant genetic diversity observed across different regions. The germplasm resources of sweet potato are distributed widely, with notable centers of diversity in Central and South America, where the crop is believed to have originated. Molecular marker analysis has revealed high genetic diversity in sweet potato germplasms from these regions, particularly in Central America, which is considered a primary center of origin (Murthy et al., 2021). New Guinea is recognized as a secondary center of diversity, where the introduction of sweet potato from the Northern neotropical genepool and subsequent recombination with local genotypes have led to significant genetic variation (Roullier et al., 2013). Furthermore, studies using chloroplast SSR markers have shown that sweet potato accessions from Korea, Japan, Taiwan, and the USA form distinct clusters, indicating regional differentiation in germplasm resources (Lee et al., 2019). 2.3 Historical development and evolution of sweet potato varieties in different regions The historical development and evolution of sweet potato varieties have been shaped by both natural and human-mediated processes. In New Guinea, the diversification of sweet potato is primarily attributed to the active management of the crop's reproductive biology by local farmers, who frequently incorporate plants from true seeds, leading to a high number of variants (Roullier et al., 2013). In Polynesia, archaeological evidence suggests that sweet potato was introduced pre-Columbian times, with cultivation practices adapting to local climatic conditions. For instance, in New Zealand, the discovery of ancient storage pits for sweet potato (kūmara) in the cooler southern regions indicates that early Polynesian settlers developed strategies to grow and store the crop despite challenging environmental conditions. This historical adaptation highlights the resilience and versatility of sweet potato as it spread across different regions and climates. 3 Current Status of Sweet Potato Germplasm Collection 3.1 Current state of the collection and preservation of sweet potato germplasm worldwide The global collection and preservation of sweet potato germplasm have seen significant advancements, with numerous accessions being conserved in various germplasm banks. For instance, the National Agrobiodiversity Center (NAC) has a collection of 558 sweet potato accessions, which have been analyzed for genetic diversity using chloroplast simple sequence repeat (cpSSR) markers. This analysis revealed a relatively low genetic diversity among the female parents of these accessions, indicating a need for further collection efforts to enhance the genetic base (Lee et al., 2019). Similarly, the International Potato Center (CIP) houses one of the largest collections, with nearly 6,000 accessions of cultivated sweet potato and over 1,000 accessions of crop wild relatives. This extensive collection has been genotyped to assess genetic identity, diversity, and population structure, uncovering high levels of redundancy and some genetic identity errors (Anglin et al., 2021).
RkJQdWJsaXNoZXIy MjQ4ODYzMg==