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Item Population Genetics and Anastomosis Group's Geographical Distribution of Rhizoctonia solani Associated with SoybeanAutores: Abbas, Aqleem; Fang, Xiangling; Iqbal, Shehzad; Naqvi, Syed Atif Hasan; Mehmood, Yasir; Rao, Muhammad Junaid; Hassan, Zeshan; Miño Ortiz, Roberto; Baazeem, Alaa; Moustafa, Mahmoud; Alrumman, Sulaiman; Negm, SallyRhizoctonia solani is a species complex composed of many genetically diverse anastomosis groups (AG) and their subgroups. It causes economically important diseases of soybean worldwide. However, the global genetic diversity and distribution of R. solani AG associated with soybean are unknown to date. In this study, the global genetic diversity and distribution of AG associated with soybean were investigated based on rDNA-ITS sequences deposited in GenBank and published literature. The most prevalent AG, was AG-1 (40%), followed by AG-2 (19.13%), AG-4 (11.30%), AG-7 (10.43%), AG-11 (8.70%), AG-3 (5.22%) and AG-5 (3.48%). Most of the AG were reported from the USA and Brazil. Sequence analysis of internal transcribed spacers of ribosomal DNA separated AG associated with soybean into two distinct clades. Clade I corresponded to distinct subclades containing AG-2, AG-3, AG-5, AG-7 and AG-11. Clade II corresponded to subclades of AG-1 subgroups. Furthermore, AG and/or AG subgroups were in close proximity without corresponding to their geographical origin. Moreover, AG or AG subgroups within clade or subclades shared higher percentages of sequence similarities. The principal coordinate analysis also supported the phylogenetic and genetic diversity analyses. In conclusion, AG-1, AG-2, and AG-4 were the most prevalent AG in soybean. The clade or subclades corresponded to AG or AG subgroups and did not correspond to the AG’s geographical origin. The information on global genetic diversity and distribution will be helpful if novel management measures are to be developed against soybean diseases caused by R. solani.Item Morphological and Molecular Characterization of Selected Chilean Runner Bean (Phaseolus coccineus L.) Genotypes Shows Moderate Agronomic and Genetic VariabilityAutores: Arriagada, Osvin; Schwember, Andres R.; Greve, Maria Jesús; Urban, Milán O.; Cabeza, Ricardo A.; Carrasco, BasilioThe runner bean is the third most economically important Phaseolus species, which is cultivated on small-scale agriculture for the production of immature pods or to obtain dry seeds. However, despite the economic importance and agronomic potential of this species, the runner bean has been little studied from the genetic standpoint. Therefore, the main objective of this study was to characterize ten selected lines of runner bean obtained from Central (Santiago) and Southern (Valdivia and Villarica) Chile based on morphological and agronomic traits. In addition, the genetic variability of these lines was determined using 12 Inter-Simple Sequence Repeat (ISSR) markers to evaluate the potential of this germplasm for breeding and commercial purposes. As a result, the lines from Central Chile were characterized, and had a higher number of pods per plant compared to the Southern lines, although the size and weight of their seeds were lower. Moreover, a low level of genetic diversity (He = 0.251) was encountered in this population. Finally, this is one of the first studies that generate relevant and novel information on the morphological, agronomic and genetic characterization of the P. coccineus germplasm present in Chile.Item A Past Genetic Bottleneck from Argentine Beans and a Selective Sweep Led to the Race Chile of the Common Bean (Phaseolus vulgaris L.)Autores: Arriagada, Osvin; Arévalo, Bárbara; Pacheco, Igor; Schwember, Andrés R.; Meisel, Lee A.; Silva, Hermán; Márquez, Katherine; Plaza, Andrea; Pérez Díaz, Ricardo; Pico Mendoza, José; Cabeza Pérez, Ricardo Alfonso; Tapia, Gerardo; Fuentes, Camila; Rodríguez Álvarez, Yohaily; Carrasco, BasilioThe domestication process of the common bean gave rise to six different races which come from the two ancestral genetic pools, the Mesoamerican (Durango, Jalisco, and Mesoamerica races) and the Andean (New Granada, Peru, and Chile races). In this study, a collection of 281 common bean landraces from Chile was analyzed using a 12K-SNP microarray. Additionally, 401 accessions representing the rest of the five common bean races were analyzed. A total of 2543 SNPs allowed us to differentiate a genetic group of 165 accessions that corresponds to the race Chile, 90 of which were classified as pure accessions, such as the bean types 'Tortola', 'Sapito', 'Coscorron', and 'Frutilla'. Our genetic analysis indicates that the race Chile has a close relationship with accessions from Argentina, suggesting that nomadic ancestral peoples introduced the bean seed to Chile. Previous archaeological and genetic studies support this hypothesis. Additionally, the low genetic diversity (pi = 0.053; uHe = 0.53) and the negative value of Tajima' D (D = -1.371) indicate that the race Chile suffered a bottleneck and a selective sweep after its introduction, supporting the hypothesis that a small group of Argentine bean genotypes led to the race Chile. A total of 235 genes were identified within haplotype blocks detected exclusively in the race Chile, most of them involved in signal transduction, supporting the hypothesis that intracellular signaling pathways play a fundamental role in the adaptation of organisms to changes in the environment. To date, our findings are the most complete investigation associated with the origin of the race Chile of common bean.Item Genetic diversity and distinctiveness of Chilean Limachino tomato (Solanum lycopersicum L.) reveal an in situ conservation during the 20th centuryAutores: Donoso, Adolfo; Carrasco, Basilio; Araya, Carolina; Salazar, ErikaLandraces constitute a valuable genetic pool of increased diversity that can be exploited for agriculture sustainability, food security, food quality, and future yield increments. It also contributes to understanding a species' origin, domestication, population dynamics, and diversity. Chilean tomato germplasm characterization and documentation are scarce. To elucidate its potential and distinctiveness, we assessed the genetic variability between and within accessions of tomato landraces grown in Chile between 1938 and 2016, determining the relationships between them and with some European and US heirloom varieties. For this purpose, the tomato plants were characterized using 72 descriptors for vegetative and reproductive morphology. In addition, molecular diversity and the determination of genetic patterns between tomato accessions were made using highly informative SSR markers. Our results indicate that the genetic structure among evaluated accessions is associated with differences between the Chilean landraces grown to 1938 and cultivars grown in Europe and USA. The Chilean cluster presented a high variability. The Limachino tomato landrace is close to Marmande but distinguishable on phenotype and the molecular basis for its private alleles, being grown in the territory of Limache before 1960 until the present day. Accessions of pink beefsteak tomato grown in Chile to 2015 are distant to the rest of the tomato accessions on morphotype and close in SSR genotype to the materials grown in Chile in 1938, supporting the hypothesis of a pre-green revolution tomato diversification in Chilean territory. Chilean tomato populations may impact breeding programs due to higher variability in yield components. Our results are consistent with other researchers that have proposed Mesoamerica and the Andes Region as tomatoes' primary center of diversity.Item Genetic and morphological characterization of the endangered Austral papaya Vasconcellea chilensis (Planch. ex A. DC.) SolmsAutores: Carrasco, B.; Garcia-Gonzales, R.; Diaz, C.; Avila, P.; Caceres, P.; Lobos, GA.; Silva, H.; Caligari, PDS.The Austral papaya (Vasconcellea chilensis) is an endangered species that has valuable characteristics for introgression into other papaya species. These characteristics include disease resistance, cold tolerance and latex with low proteolytic activity. It is a species that grows under extreme environmental conditions of drought, salinity and temperature; it is found growing naturally in Chile but today only as three remnant populations. The results presented here, using inter simple sequence repeat molecular markers, along with morphological trait analyses, suggest that these relict populations are the result of a relatively recent fragmentation. This implies that the fragmentation has not yet had its full effect on the genetic variation and so emphasises the need for clear and urgent conservation measures to preserve the remaining genetic variation, particularly for the most northern of the three populations which is presently unprotected.
