Diversity Of Sweet Potato Research Articles

Characterization and studies of genetic diversity of sweet potato from Paraguay

El objetivo fue caracterizar genotipos y obtener datos sobre la diversidad genética de batata. El diseño fue en BCA con 26 tratamientos y tres repeticiones. Fueron evaluadas productividad total, rendimiento comercial y no comercial de raíz (t ha-1), número de raíces por planta, biomasa aérea, forma y color de la raíz. La diversidad genética fue obtenida por la medida de disimilaridad media similares y para delimitación de grupos se utilizó el método de dendrograma UPGMA. Como medida de proximidad de distancias se utilizó la medida de disimilitud Euclidiana Cuadrática. La cantidad de clusters fue por el Criterio de Mojena. El mayor número de accesiones fue agrupado en el cluster III, con nueve accesiones, cluster II con seis accesiones, cluster IV, con seis accesiones, cluster VII con dos accesiones y cluster I, V y VII con una accesión cada una. La mayor distancia genética fue entre Morotí Guazú (6) e Ib-019 (23) con 40.443 y los más similares resultaron Morado (3) y Pyta guazú (9) con un valor de 1098. La productividad de raíces es la variable de mayor importancia para la distancia genética. El color predominante de la piel de la colección es crema y color de carne amarillo pálido.

Genetic diversity of local sweet potato cultivars (Ipomoea batatas [L.] Lam.) from Bulungan, North Kalimantan based on morphological characters

Indonesia is one of the centers of sweet potato diversity worldwide. Sweet potatoes have the potential to be developed for food consumption. This research aims to determine the diversity of sweet potato cultivars, their morphological characteristics, and the relationships between local sweet potato cultivars in Bulungan Regency, North Kalimantan. The local sweet potato cultivars were selected using purposive sampling with the exploration method. The morphological characterization of the samples is based on IBPGR (International Board for Plant Genetic Resources) standards. Cluster analysis was conducted to identify the relationships using MVSP software version 3.1. The research identified 27 local sweet potato cultivars in Bulungan Regency. Morphological characterization revealed 41 characters that can differentiate each local sweet potato cultivar. The most influential characteristics include leaf shape, flower surface texture, the position of the stigma, flower surface color, back petal color, center shape and the number of lobes, primary leaf vein color, lobe type, main leaf bone color, stem internode length, and plant type. A flower shape that had not been discovered before, a pentagonal shape with curves, was identified. Cluster analysis divided the cultivars into two major groups with a coefficient range of 0.593 to 0.888 (59.3 to 88.8%). Cluster A consisted of one member, LK-7 (purple sweet potato), while Cluster B consisted of several subgroups with 26 local cultivars. The people of Bulungan Regency use these local cultivars for food, animal feed, and medicinal purposes.

Identifikasi karakteristik morfologi, sistem budidaya, dan pemanfaatan ubi jalar (Ipomoea batatas L.) oleh masyarakat lokal di Distrik Wanggar Kabupaten Nabire

ABSTRACT: Sweet potato (Ipomoea batatas L.) is one of the world's most important food crops with great potential to be developed in Indonesia. This plant is rich in carotenoids and anthocyanins. Anthocyanin compounds in sweet potatoes function as components of healthy food. The purpose of this study was to identify the morphological diversity of sweet potato accessions, cultivation systems, and utilization of local communities in Wanggar District, Nabire Regency. The method used in this research is descriptive method with direct observation techniques in the field, at 3 villages: namely Wiraska, Wanggar Sari, and Karadiri in the Wanggar District, Nabire Regency. Data on sweet potato diversity were analyzed using cluster analysis with the NTSYS version 2.0 program. The result of this research are: (1) At the research sites in the villages of Wanggar Sari, Wiraska, and Karadiri there were 6 cultivars of sweet potato plants based on local names, namely: Unggu, Mokupudugu, Ueta, Mokupudugu, Nota, and Gelakue genotypes. These 6 cultivars had a diversity of morphological characters, (2) Based on the results of the cluster analysis, there are 2 main clusters that have the lowest similarity in morphological characters (34%), namely Cluster I (Unggu and Gelakue) and Cluster II (Makupudugu, Nota, Ueta, Kilumbi). The genotypes of Ungu and Gelakue in Cluster I have similar morphological characters of 43%, (3) Local communities in the Wanggar District still use traditional sweet potato cultivation systems and techniques that have been used from generation to generation, from land clearing to harvesting, and (4) In addition to being used as food, the plant parts of sweet potatoes are also used based on local wisdom communities as traditional medicines and natural fertilizers.

Genetic diversity assessment and genome-wide association study reveal candidate genes associated with component traits in sweet potato (Ipomoea batatas (L.) Lam)

The Korean sweet potatoes were bred by various cultivars introduced from Japanese, American, Porto Rico, China, and Burundi. This issue enriched their genetic diversity but also resulted in a mixture of cultivars. For genotyping, we collected and sequenced 66 sweet potato germplasms from different localities around Korea, including 36 modern cultivars, 5 local cultivars, and 25 foreign cultivars. This identified 447.6 million trimmed reads and 324.8 million mapping reads and provided 39,424 single nucleotide polymorphisms (SNPs) markers. Phylogenetic clustering and population structure analysis distinctly classified these germplasms into 5 genetic groups, group 1, group 2, group 3, group 4, and group 5, containing 20, 15, 10, 7, and 14 accessions, respectively. Sixty-three significant SNPs were selected by genome-wide association for sugar composition-related traits (fructose, glucose, and total sugars), total starch, amylose content, and total carotenoid of the storage root. A total of 37 candidate genes encompassing these significant SNPs were identified, among which, 7 genes were annotated to involve in sugar and starch metabolism, including galactose metabolism (itf04g30630), starch and sucrose metabolism (itf03g13270, itf15g09320), carbohydrate metabolism (itf14g10250), carbohydrate and amino acid metabolism (itf12g19270), and amino sugar and nucleotide sugar metabolism (itf03g21950, itf15g04880). This results indicated that sugar and starch are important characteristics to determine the genetic diversity of sweet potatoes. These findings not only illustrate the importance of component traits to genotyping sweet potatoes but also explain an important reason resulting in genetic diversity of sweet potato.

KARAKTER MORFOLOGI TIGA KLON UBI JALAR DI MALUKU

Sweet potato (Ipomoea batatas (L.) Lam.) is one of the main carbohydrate sources in Mollucas and is a carbohydrate source food crop after rice, corn and cassava in Indonesia. In order to be able to identify the various characteristics of sweet potato clone collected, it is necessary to determine the morphological character of the genetic resource diversity characteristics that are most influential on sweet potato diversity. The aim of the study was to characterize the morphology of some sweet potatoes as potential yields in Mollucas. The results of the study were that the morphological characteristics of the three sweet potato clones in Mollucas had different colors, shapes on the leaves, stems, flowers, seeds and tubers

Morphological Characteristics of Varieties of Sweet Potato, Cenoura, Margarita, Rainha and Roxa, Cultivated in Amazonas, Brazil

Sweet potato [Ipomoea batatas (L.) Lam.] is a nutritious food, from an easy-to-handle cultivation, present in all Brazilian regions, with great socioeconomic relevance. There is a wide genetic diversity of sweet potato, expressing different flesh and skin colors, and containing different nutritional values. However, only sweet potatoes with cream flesh and white or purple skin are present in the Manaus market. It is important to promote the visibility of the varieties that are being cultivated in a less expressive way, often only by the indigenous people. In this way, the valorization of the product and the conservation of agrobiodiversity will be encouraged. One obstacle to identifying varieties is that the same variety can have different names, and the same name can be given to different varieties. Therefore, it is essential that a morphological description of the varieties present locally is made. This will be a subsidy for future research and actions aimed at the development of the primary sector that has the sweet potato as its object. Given the above, this work aimed to morphologically describe the sweet potato varieties Cenoura, Margarita, Rainha and Roxa present at the Experimental Farm of the Federal University of Amazonas. The Cenoura, Rainha and Roxa varieties have different skin and/or flesh colors and a tuberous root shape, catering to different consumer tastes. The Cenoura variety (skin and orange flesh) has the potential to be cultivated by Amazonian farmers and introduced in the local market (Alves, 2021; Filgueira, 2008; Huamán, 1991).

Identification of the genetic diversity of sweet potato germplasm based on quantitative morphological characters

Sweet potato is one of the prospective food crops to be used as an export commodity. Information on genetic diversity of sweet potato is needed as a consideration for the improvement of superior sweet potato varieties that have export quality. The research was conducted in Wringin Songo village, Tumpang, Malang Regency. The materials used were 150 sweetpotato accessions in total that consisting of: 19 superior varieties, 38 local clones, 1 introduced variety and 92 promising clones. This experiment was arranged in randomized block design (RBD) with two replications. The qquantitative morphological variables such as: potential yield, tuber weight, dry matter, stover weight, harvest index and number of tubers plot−1 were observed. The results showed that the genetic diversity was quite high in the sweet potato germplasm, there were 41 clones that had yield potential (≥ 30 t ha−1). Some of these clones were prospective to be used as parents for crossing due to their ability to flower. Two sweet potato clones (MSU 10001-18 and MSU 07030-64) with dark purple flesh colour, Kidal variety with yelow flesh color and above 30% tuber dry matter have the criteria required for export market.

Genotypic and environmental factors influence the proximate composition and quality attributes of sweetpotato (Ipomoea batatas L.)

BackgroundSweetpotato is an important staple food crop worldwide. The genotype mainly influences the nutritional quality of its storage roots, but environmental conditions could produce significant variations in chemical composition and quality. The aim of this study was to characterize sweetpotato diversity of 20 selected genotypes and identify harvest time (90, 120, and 150 days after planting-DAP) and environmental effects on quality attributes estimated by proximate analysis (dry matter, ash, crude fiber, total protein, and total soluble solids). Red (R), green (G), and blue (B) (RGB) analysis was used to characterize the genotypes phenotypically.ResultsThe results of the current study revealed that flesh color was associated with proximate composition. RGB analysis showed that low B pixel values were present in yellow–orange- and purple-fleshed genotypes, which simultaneously exhibited high total protein content (TPC), ash content (AC), and crude fiber (CF), while cream- and white-fleshed genotypes showed high B pixel values and were related to high dry matter content (DMC). In these genotypes, the high DMC was maintained or increased through harvest time, however, a reduction in the proportion of accumulated AC and TPC was observed. On the other hand, in the pigmented genotypes, DMC increased up to 120 DAP, showing major stability in terms of AC and TPC. Regardless of harvest time, more intense rain events 30 days before harvest, affected the storage of DMC in roots negatively, while AC, TPC, and CF were accumulated more efficiently, or their proportion increased. High temperatures increased total soluble solids (TSS) accumulation and reduced AC, TPC, and CF accumulation. The combined analysis, according to the additive main effects and multiplicative interaction (AMMI) model, confirmed these results.ConclusionsThese findings indicated that white-fleshed genotypes contain high DMC, although, with lower TPC, AC, and CF contents compared to yellow–orange- and purple-fleshed genotypes. Although there is an increase in DMC in extended harvests (in orange-fleshed genotypes up to 120 DAP), the presence of pre-harvest rain promotes its translocation and loss. On the contrary, TPC, AC, and CF can be kept stable or even increase, except in environments with high temperatures that induce low accumulation. The current study provides a better understanding of the nutritional response of sweetpotato diversity under several growing conditions, which can be recognized and used integrally to improve food quality.

Genetic diversity of sweet potatoes [Ipomoea batatas (L) Lam.] in Ecuador

The present work considered collecting and characterizing the genetic diversity of sweet potato [Ipomoea batata (L.) Lam.] in Ecuador through morphological and molecular descriptors (SSRs). Germplasm collections were made to assemble a national sweet potato collection for Ecuador. Characterization of the genetic diversity of this species was done through 34 morphological descriptors (24 qualitative and 10 quantitative), plus 12 exclusive descriptors for flowering and 8 microsatellites (SSRs). Three hundred and sixty-eight sweet potato accessions were collected in 18 provinces of Ecuador. Morphological characterization showed seven morphological groups and the variables with the greatest discriminating power for the description of the germplasm (p < .001) were the color, shape and defects of the reservoir root, in addition to the shape of the profile and lobes of the leaves. Principal component analysis determined the association of the main quantitative morphological features to the components. Eight microsatellite markers detected 89 alleles, with an average of 11.12 allele/locus and average polymorphism (PIC) of 0.848. STRUCTURE software revealed the formation of 4 different genetic groups. Morphological and molecular data did not show the formation of any group defined according to the province of origin. Factors such as the sweet potato reproductive system (cross-pollination), random sweet potato mutations and farmer exchange, contributed to the greater genetic diversity present. High genetic diversity and low number of duplicates were identified. This collection could provide outstanding genotypes to be used in breeding programs. Local landraces still in the hands of local farmers suggest that in situ conservation projects must be put in place.

Flesh Color Diversity of Sweet Potato: An Overview of the Composition, Functions, Biosynthesis, and Gene Regulation of the Major Pigments

Sweet potato is a multifunctional root crop and a source of food with many essential nutrients and bioactive compounds. Variations in the flesh color of the diverse sweet potato varieties are attributed to the different phytochemicals and natural pigments they produce. Among them, carotenoids and anthocyanins are the main pigments known for their antioxidant properties which provide a host of health benefits, hence, regarded as a major component of the human diet. In this review, we provide an overview of the major pigments in sweet potato with much emphasis on their biosynthesis, functions, and regulatory control. Moreover, current findings on the molecular mechanisms underlying the biosynthesis and accumulation of carotenoids and anthocyanins in sweet potato are discussed. Insights into the composition, biosynthesis, and regulatory control of these major pigments will further advance the biofortification of sweet potato and provide a reference for breeding carotenoid- and anthocyanin-rich varieties.

Morphometric and colourimetric tools to dissect morphological diversity: an application in sweet potato [Ipomoea batatas (L.) Lam.

The genetic diversity of sweet potato [Ipomoea batatas (L.) Lam.] and its wild relatives has been collected and conserved in germplasm collections worldwide and explored employing several tools. The characterization of crops diversity through morphological tools produce useful information. However, the use of conventional morphological descriptions exhibits limitations due to the use of subjective and categorical parameters that affect phenotypic description and diversity estimation. In order to increase the efficiency to discriminate different phenotypes not detected by conventional morphological descriptors, new phenomic approaches were used. Seventy sweet potato accessions collected in the northern coast of Colombia were characterized by forty-nine parameters from conventional sweet potato descriptors and data obtained by RGB imaging and colourimetry. Field descriptions, RGB imaging-colourimetry and both databases integrated were analysed using Gower’s general similarity coefficient for clustering. Estimation of genotype similarity was significantly improved when quantitative data obtained by RGB imaging and colourimetry analysis were included. Variations in traits such as flesh and periderm colour in roots, leaves, vein colour and leaf shape that were not detected by field descriptors, were efficiently discriminated by measuring pixel values from images, estimation of shape descriptors (circularity, solidity, area) and colourimetry data. Expected high correlations were found for field parameters (number of lobes, lobe type, and central lobe shape) and image data (circularity, roundness and solidity). The combination of RGB imaging and colourimetry benefits the quality of morphological characterizations, resulting in a cost-effective process that is able to identify polymorphisms and target traits for diversity estimation and breeding.

Analysis of evolution and genetic diversity of sweetpotato and its related different polyploidy wild species I. trifida using RAD-seq

BackgroundSweetpotato (Ipomoea batatas (L.) Lam.) is one of the most important crops from the family of Convolvulaceae. It is widely reported that cultivated sweetpotato was originated from Ipomoea trifida. However, diploid, tetraploid and hexaploid I. trifida were found in nature. The relationship, between them, and among them and sweetpotato, is remaining unclear.ResultsIn the present study, we detected the genome diversity and relationship of sweetpotato and different polyploidy types I. trifida using Restriction-site Associated DNA Sequencing (RAD-seq). A total of 38,605 RAD-tags containing 832,204 SNPs had been identified. These tags were annotated using five public databases, about 11,519 tags were aligned to functional genes in various pathways. Based on SNP genotype, phylogenetic relation analysis results confirmed that cultivated sweetpotato has a closer relationship with I. trifida 6× than with I. trifida 4X and I. trifida 2×. Besides, 5042 SSRs were detected in I. trifida 6×, and 3202 pairs of high-quality SSR primers were developed. A total of 68 primers were randomly selected and synthesized, of which 61 were successfully amplified.ConclusionThese results provided new evidence that cultivated sweetpotato originated from I. trifida 6×, and that I. trifida 6× evolved from I. trifida 4X and I. trifida 2×. Therefore, using I. trifida 6× as the model plant of sweetpotato research should be more practical than using I. trifida 2× in the future. Meanwhile, sequence information and markers from the present study will be helpful for sweetpotato and I. trifida studies in the future.

Structure of New Zealand sweetpotato starch

New Zealand sweetpotatoes (kumara) (Ipomoea batatas) represent unique genetic resources for sweetpotato diversity, though they are much under-studied. In this study, 7 New Zealand sweetpotato varieties with commercial significance were collected for the characterization of the molecular and granular structure of the starches. In particular, the internal molecular structure of the amylopectins was detailed by chromatographic and enzymatic techniques. Maize and potato starches with normal amylose contents, which are among the most important commercial starch sources, were employed for comparison. The results revealed a degree of diversity in amylose composition, unit and internal chain composition, granule size distribution, and degree of crystallinity among the 7 sweetpotato starches. All the sweetpotato starches showed CA-type polymorph. The sweetpotato amylopectins have intermediate amounts of both short and long internal unit chains among amylopectins of different botanical sources. The differences in the structure of sweetpotato starches suggest differences in physicochemical properties.

English

Characterization of landraces is central to any conservation measures devised for sweet potato in Malawi. Studies were therefore conducted using seven morphological descriptors and farmers’ indigenous knowledge systems (IKS) to investigate the phenotypical diversity of 286 landraces and 35 introductions of sweet potato from the north, south east and lower Shire. The accessions were planted in a check plot design at Bvumbwe Agricultural Research Station. The results showed that farmers’ knowledge (IKS) is a means for preliminary characterization of accessions as evidenced by elimination of 75 duplicate accessions by 12 farmers. Analysis of variance (ANOVA) showed that all accessions and populations were phenotypically variable (p≤0.01) and Chi-square test of the morphological descriptors used in the study varied significantly among the three eco-geographical areas and among the landraces and introductions (p≤0.05 and p≤0.01), implying high variability of the accessions. However, the accessions clustered at 50% dissimilarity and generally irrespective of eco-geographical origin, signifying some similarity probably due to gene flow. Shannon Weaver Diversity Index (H’) indicated that different traits had different source areas of highest diversity which were significantly different (p≤0.05); nonetheless Shire Valley had the highest mean diversity for all traits (H’=0.67) which was significantly different from the other two populations (p≤0.05) inferring that the lower shire would be ideal for in situ conservation of sweet potato diversity. Key words: Field evaluation, germplasm, phenotype, population, root crop, variability.

Characterizing the diversity of sweetpotato through growth parameters and leaf traits: Precocity and light use efficiency as important ordination factors

Due to its low-input requirements, high yield capacity in marginal soils, and high carbohydrate and vitamin A content, sweetpotato is an important food security crop. For effective breeding strategies, knowing and understanding the traits that drive diversity among varieties is required. In this study, a set representing the diversity of sweetpotato varieties was characterized through multivariate ordination based on growth parameters and physiological leaf traits. The dynamic of light interception, light use efficiency (LUE) parameters, and partition of assimilates to the storage roots of eight representative varieties were simulated through a crop growth model. Leaf mass per area (LMA), N and P content in leaves, light response curve parameters and carbon discrimination were assessed in potted plants at early-growing period (58days after planting). Precocity proxies (inversely related to LMA and thermal time at maximum storage root growth) and conversion efficiency of intercepted radiation indicators (quantum yield and LUE) were important factors in the varieties ordination based on leaf traits and growth parameter scales, respectively. Leaf traits assessment at early stages could be used as a starting point for the screening of potential lines, which once identified can be further characterized using crop growth models.

Genome-wide assessment of population structure and genetic diversity and development of a core germplasm set for sweet potato based on specific length amplified fragment (SLAF) sequencing.

Sweet potato, Ipomoea batatas (L.) Lam., is an important food crop that is cultivated worldwide. However, no genome-wide assessment of the genetic diversity of sweet potato has been reported to date. In the present study, the population structure and genetic diversity of 197 sweet potato accessions most of which were from China were assessed using 62,363 SNPs. A model-based structure analysis divided the accessions into three groups: group 1, group 2 and group 3. The genetic relationships among the accessions were evaluated using a phylogenetic tree, which clustered all the accessions into three major groups. A principal component analysis (PCA) showed that the accessions were distributed according to their population structure. The mean genetic distance among accessions ranged from 0.290 for group 1 to 0.311 for group 3, and the mean polymorphic information content (PIC) ranged from 0.232 for group 1 to 0.251 for group 3. The mean minor allele frequency (MAF) ranged from 0.207 for group 1 to 0.222 for group 3. Analysis of molecular variance (AMOVA) showed that the maximum diversity was within accessions (89.569%). Using CoreHunter software, a core set of 39 accessions was obtained, which accounted for approximately 19.8% of the total collection. The core germplasm set of sweet potato developed will be a valuable resource for future sweet potato improvement strategies.

Evaluation of genetic diversity of sweet potato [Ipomoea batatas (L.) Lam.] on different ploidy levels applying two capillary platforms

ABSTRACTThe genetic composition of sweet potato [Ipomoea batatas (L.) Lam.] (2n = 6x = 90) is reflected in different levels of genetic variation. The main objective of the present study was a comparison of genetic diversity parameters of different ploidy levels (2n, 4n, and 6n codominant allele determination), analyzed on two high-resolution capillary platforms. Fragment analysis was performed by applying SSR markers on a 3130XL Genetic Analyzer (ABI 3130) and QIAxcel Advanced System (QX). A high level of expected heterozygosity (He) as a measure of genetic diversity was observed for both ABI3130 (0.731) and QX (0.679). Molecular variance was 17% for ABI3130 and 10% for QX. Comparison between genetic distance matrices based on allele lengths showed a moderate Mantel correlation coefficient (rxy = 0.557) between ABI3130 and QX. Global cluster analysis using the Bayesian approach distributed the observed genotypes into two clusters on both capillary platforms. Our results show that the two high-resolution capillary electrophoreses for codominant data on 2n, 4n, and 6n levels are applicable in genetic diversity studies but their efficiency depends on in-resolution expectations, financial resources, available time, and the equipment of the laboratory.

Genetic Bottlenecks for Two Populations of Ceratocystis fimbriata on Sweet Potato and Pomegranate in China.

Chinese isolates of Ceratocystis fimbriata from sweet potato (Ipomoea batatas) and pomegranate (Punica granatum) were genetically compared with a worldwide collection of isolates from a variety of hosts. Isolates from black-rotted storage roots of sweet potato in China, Japan, Australasia, and the United States had identical internal transcribed spacer (ITS) ribosomal DNA (rDNA) sequences and only minor variation in microsatellite alleles. Sequences of their mating type genes were most similar to those of isolates from various hosts in Ecuador, a center of diversity for sweet potato. Isolates from Colocasia esculenta (taro) and pomegranate from Yunnan and Sichuan had only one ITS rDNA sequence (haplotype ITS5). This haplotype, sequences of mating type genes, and microsatellite alleles linked these isolates to isolates from Eucalyptus stumps in South China and diseased Eucalyptus trees in Brazil, supporting the hypothesis that the pomegranate population originated from Brazil via cuttings of Eucalyptus. Isolates from sweet potato and pomegranate in China were interfertile with tester strains of C. fimbriata, confirming that the causes of the two epidemics in China belong to a single biological species. However, other isolates from Eucalyptus stumps were intersterile with the tester strains and had ITS rDNA sequences typical of the Asian species, C. cercfabiensis.

Simple Sequence Repeat Marker Analysis of Genetic Diversity among Progeny of a Biparental Mapping Population of Sweetpotato

Genetic diversity is critical in sweetpotato improvement as it is the source of genes for desired genetic gains. Knowledge of the level of genetic diversity in a segregating family contributes to our understanding of the genetic diversity present in crosses and helps breeders to make selections for population improvement and cultivar release. Simple sequence repeat (SSR) markers have become widely used markers for diversity and linkage analysis in plants. In this study, we screened 405 sweetpotato SSR markers for polymorphism on the parents and progeny of a biparental cross of New Kawogo × Beauregard cultivars. Thereafter, we used the informative markers to analyze the diversity in this population. A total of 250 markers were polymorphic on the parents and selected progeny; of these, 133 were informative and used for diversity analysis. The polymorphic information content (PIC) values of the 133 markers ranged from 0.1 to 0.9 with an average of 0.7, an indication of high level of informativeness. The pairwise genetic distances among the progeny and parents ranged from 0.2 to 0.9, and they were grouped into five main clusters. The 133 SSR primers were informative and are recommended for use in sweetpotato diversity and linkage analysis.

Assessment of genetic diversity of sweet potato in Puerto Rico.

Sweet potato (Ipomoea batatas L.) is the seventh most important food crop due to its distinct advantages, such as adaptability to different environmental conditions and high nutritional value. Assessing the genetic diversity of this important crop is necessary due to the constant increase of demand for food and the need for conservation of agricultural and genetic resources. In Puerto Rico (PR), the genetic diversity of sweet potato has been poorly understood, although it has been part of the diet since Pre-Columbus time. Thus, 137 landraces from different localities around PR were collected and subjected to a genetic diversity analysis using 23 SSR-markers. In addition, 8 accessions from a collection grown in Gurabo, PR at the Agricultural Experimental Station (GAES), 10 US commercial cultivars and 12 Puerto Rican accessions from the USDA repository collection were included in this assessment. The results of the analysis of the 23 loci showed 255 alleles in the 167 samples. Observed heterozygosity was high across populations (0.71) while measurements of total heterozygosity revealed a large genetic diversity throughout the population and within populations. UPGMA clustering method revealed two main clusters. Cluster 1 contained 12 PR accessions from the USDA repository collection, while cluster 2 consisted of PR landraces, US commercial cultivars and the PR accessions from GAES. Population structure analysis grouped PR landraces in five groups including four US commercial cultivars. Our study shows the presence of a high level of genetic diversity of sweet potato across PR which can be related to the genetic makeup of sweet potato, human intervention and out-crossing nature of the plant. The history of domestication and dispersal of sweet potato in the Caribbean and the high levels of genetic diversity found through this study makes sweet potato an invaluable resource that needs to be protected and further studied.