East Africa is known to have a wide range of sweet potato landraces and, therefore, is considered to be a secondary center of diversity. In this study, we assessed the diversity among sweet potato landraces from Kenya, Uganda and Tanzania using morphological and simple sequence repeats (SSR) markers. Two hundred and sixty-six landraces collected from agro-ecologically-distinct locations were screened for morphological characters using the CIP Research Guide. Morphological characters were recorded and phylogenetic analysis using UPGMA showed a close relatedness amongst the East African sweet potato landraces with the majority having a 0.1-0.5 range of Nei’s genetic distance from each other. The landraces, however, formed two major sub-clusters, irrespective of geographical origin. Based on the morphological analysis, 57 landraces that were fairly distant were further analysed using four SSR primers specific for sweet potato. Each primer pair was able to generate between two and five polymorphic and clearly scorable fragments. Phylogenetic analysis using UPGMA revealed similar results for the morphological characters. However, in each analysis, landraces from Tanzania tended to cluster together, suggesting that they are morphologically and genetically distinct from the Kenyan and Ugandan accessions. AMOVA, performed to further examine the relationships, indicated greater diversity than revealed by phylogenetic analysis suggesting that SSR markers are more reliable in assessing genetic diversity.

采用RAPD技术分析了国内外37种抗PVY马铃薯资源。提取马铃薯(Solanumtuberosum)新鲜叶片的总DNA,用17种RAPD引物进行随机多态性扩增,利用遗传多样性信息,进行亲源关系的分子鉴定。试验表明:平均每10个碱基引物扩增出6￣21条谱带,共获得164条特异性谱带,平均每个引物扩增获得9.8条多态性谱带,多态性比率平均为76.3%。RAPD分析表明37种抗PVY马铃薯资源之间的遗传距离介于0.06￣0.68之间,平均值为0.35,平均遗传距离介于0.27￣0.50之间,聚类分析将37种抗PVY材料划分为三个类,聚类结果同材料的血缘关系密切,并且表现出一定的地域特性。根据扩增的特异性谱带可进行抗PVY马铃薯资源的分子鉴定,为抗PVY育种亲本选配提供了依据。

The cultivated potato is a major crop worldwide. It is a high input crop with complex quality requirements at harvest and during storage. Potato breeders are fortunate to have access to a very diverse and accessible germplasm resource. Wild Solanum relatives provide genetic diversity as well as genes for valuable production and quality traits. In most cases, crossing success can be predicted based on endosperm balance number (EBN), or effective ploidy, of the parents. Crossing barriers between most wild species and the cultivated potato are the consequence of differences in EBN and can be easily overcome using ploidy manipulations and bridge crosses. The most common ploidy manipulations include haploid extraction to reduce EBN and 2n gamete production to increase EBN. Additional methods to produce fertile interspecific hybrids include mentor pollination, embryo rescue, hormone treatments, reciprocal crosses, selection of cross-compatible genotypes and somatic fusion. Knowledge of crossing barriers and mechanisms to overcome them allows potato breeders access to the rich gene pool in the genus Solanum.

The application of these methods for early diagnosis of 4 Fusarium species are included F.oxysporrium F.sp vasinfectum, F.oxysporium cubense on banana, F.miniliforrme on onion and F.solani on tomato and potato. Genetic diversity among isolates of Fusarium spp. of Vietnam were compared with isolates from Korea and Egypt by using AFLP methods show that the truncation levels at 0,60 correlation, allowed separation into two groups; major group (3 clusters included F.oxysporium cubensse, F.solani and F.avenaceum species) and subgroup is cluster of F.miniliforme specie. The results of the present study show that AFLP polymorphic of genetic diversity to geographic origin, host genotype of test isolates are clear.

Potato yellow vein virus (PYVV) causes dramatic yield reductions in potatoes in Andean countries, particularly Colombia. We tested 250 potato leaf samples suspectedly infected with PYVV from three Colombian Departments and assessed genetic diversity in the coat protein gene of 18 representative isolates by RT-PCR-RFLP analysis with HinfI. RFLP profiles revealed that 80% of these isolates had an identical restrictotype while the remaining isolates comprised two further restrictotypes or mixtures of two restrictotypes which included the predominant type and one other type. In samples from the Cundinamarca and Antioquia Departments, all three restrictotypes were detected including mixed infections, whereas in samples from the Narino Department only the predominant restrictotype was detected.

The complete nucleotide sequence of the chloroplast genome of potato Solanum tuberosum L. cv. Desiree was determined. The circular double-stranded DNA, which consists of 155,312 bp, contains a pair of inverted repeat regions (IRa, IRb) of 25,595 bp each. The inverted repeat regions are separated by small and large single copy regions of 18,373 and 85,749 bp, respectively. The genome contains 79 proteins, 30 tRNAs, 4 rRNAs, and unidentified genes. A comparison of chloroplast genomes of seven Solanaceae species revealed that the gene content and their relative positions of S. tuberosum are similar to the other six Solanaceae species. However, undefined open reading frames (ORFs) in LSC region were highly diverged in Solanaceae species except N. sylvestris. Detailed comparison was identified by numerous indels in the intergenic regions that were mostly located in the LSC region. Among them, a single large 241-bp deletion, was not associated with direct repeats and found in only S. tuberosum, clearly discriminates a cultivated potato from wild potato species Solanum bulbocastanum. The extent of sequence divergence may provide the basis for evaluating genetic diversity within the Solanaceae species, and will be useful to examine the evolutionary processes in potato landraces.

The collections of drug and feed plants and potato from Siberia and problems of their formation, studying and use are considered. The collections include more than 10 000 samples, which are members of 125 species from 24 families. In 2006 the collection was added by 130 samples of perennial and forage grasses. The collection studying resulted in development of data base for potato, amaranth and winter wheat (each one consists of more than 100 documents). These data are online available. Each one contains information about plant morphology, productivity and its elements, biochemical composition and also plant photographs. Polymorphism of iso-enzymatic systems of alcohol-, glutamate-, malat- and isocytrate dehydrogenase in amaranth is studied. Genetic control of theses systems is established. The possibility of using enzyme loci polymorphism for characterization infraspecific and intergenetic diversity is confirmed. The study of American lucerne cultivars according their winter hardness, productivity, development rithms and resistance to ascochyta-leaf spot (Ascochyta imperfecta) is completed. Genetic diversity of the cultivars, their high suitability for West Siberia conditions and their perspectiveness as initial material are determined. The new high-yielding amaranth cultivar Yantar for universal use (as forage and as grain) is an example of the collection use for breeding. Yantar is characterized by high adaptability and it is recommended to be grown in 5 regions of Siberia and Altay territory.

A streamlined life cycle assessment (SLCA) was conducted to determine the environmental performance of sweet potato production in lahar-affected areas of Moncada, Tarlac. Key informant interviews, focus group discussions and farm household survey were used. Nutrient balance, global warming, eutrophication and atmospheric acidification potentials and resource energy were estimated. T-test was used to compare the environmental performance of the farms of the members and non-members of the cooperative. One ton of sweet potato is the functional unit. The systems boundary was from planting to the trading post. Quantitative estimates of average environmental burdens generated by sweet potato production in terms of global warming and atmospheric acidification potentials from diesel fuel and eutrophication potential from nitrates and phosphates were estimated for both groups. The estimated surplus nitrogen (29.54 kg/ha) and phosphorus (28.84 kg/ha) were higher in farms of cooperative members than that of non-members (1.75 kg N/ha and 7.95 kg P/ha). The farms of both had negative balance in terms of potassium. Farms of cooperative members had significantly higher eutrophication potential that that of non-cooperative members, but the amounts were low. They were not significantly different in global warming potential. The atmospheric acidification potential was higher in the farms of cooperative members than that of non-cooperative members. The soil in the study site is moderately susceptible to soil erosion. The low genetic diversity of sweet potato varieties in the area makes the crop vulnerable to biotic and abiotic stresses and hence to genetic erosion. The study recommended crop management practices to improve the environmental performance of sweet potato production and to address existing and emerging environmental issues and challenges that constrain its productivity and economic viability.

Advanced breeding materials and commercial cultivars that possess a number of economically important attributes are good potential building blocks of a breeding program. Their efficient utilization, nevertheless, depends on the knowledge of the genetic distance existing between them. A total of 15 potato genotypes consisting of 11 advanced breeding clonal materials at multi-locational performance trial stage and four Ethiopian converted commercial cultivars of European origin were evaluated using the molecular marker called Simple Sequence Repeat (SSR) or microsatellites to determine the genetic distance between them. Three primers flanking to the gene associated with the potato wound induced genes WIN1 and WIN2 and starch synthase were used to detect for variation in repeat length. The three primer pairs did reveal polymorphism, detecting between four and six alleles at each locus. Of these, two gave rise to complex band patterns, suggesting that multiple polymorphic loci were being amplified using a single primer pair. Consequently, 74 clearly scorable bands were recorded upon which a diversity index (H), a genetic distance matrix and cluster analysis were performed. The hetrozygosity values ranged from 0.63 to 0.82. Similarly, the genetic distance matrix ranged between 0.25 through 0.89. The lowest genetic distance was observed for the genotypes CIP-387676.24 and Tolcha whilst the maximal distance was between KP-90134.5 and CIP-387676.24. Phenetic analysis of the derived information allowed the construction of a dendrogram depicting the genetic distance between the studied genotypes. Consequently, two main clusters and three singletons were formed. The potential of microsatellite markers for genetic distance analysis and parental material selection is discussed in the light of these results.