Alterations in Gene Expression during Incompatible Interaction between Amendoim Cavalo Common Bean and Colletotrichum lindemuthianum.

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, poses a significant and widespread threat to the common bean crop. The use of plant genetic resistance has proven to be the most effective strategy for managing anthracnose disease. The Amendoim Cavalo (AC) Andean cultivar has resistance against multiple races of C. lindemuthianum, which is conferred by the Co-AC gene. Fine mapping of this resistance gene to common bean chromosome Pv01 enabled the identification of Phvul.001G244300, Phvul.001G244400, and Phvul.001G244500 candidate genes for further validation. In this study, the relative expression of Co-AC candidate genes was assessed, as well as other putative genes in the vicinity of this locus and known resistance genes, in the AC cultivar following inoculation with the race 73 of C. lindemuthianum. Gene expression analysis revealed significantly higher expression levels of Phvul.001G244500. Notably, Phvul.001G244500 encodes a putative Basic Helix-Loop-Helix transcription factor, suggesting its involvement in the regulation of defense responses. Furthermore, a significant modulation of the expression of defense-related genes PR1a, PR1b, and PR2 was observed in a time-course experiment. These findings contribute to the development of improved strategies for breeding anthracnose-resistant common bean cultivars, thereby mitigating the impact of this pathogen on crop yields and ensuring sustainable bean production.

Responsiveness of Candidate Genes on CoPv01CDRK/PhgPv01CDRK Loci in Common Bean Challenged by Anthracnose and Angular Leaf Spot Pathogens.

Anthracnose (ANT) and angular leaf spot (ALS) are significant diseases in common bean, leading to considerable yield losses under specific environmental conditions. The California Dark Red Kidney (CDRK) bean cultivar is known for its resistance to multiple races of both pathogens. Previous studies have identified the CoPv01CDRK/PhgPv01CDRK resistance loci on chromosome Pv01. Here, we evaluated the expression levels of ten candidate genes near the CoPv01CDRK/PhgPv01CDRK loci and plant defense genes using quantitative real-time PCR in CDRK cultivar inoculated with races 73 of Colletotrichum lindemuthianum and 63-39 of Pseudocercospora griseola. Gene expression analysis revealed that the Phvul.001G246300 gene exhibited the most elevated levels, showing remarkable 7.8-fold and 8.5-fold increases for ANT and ALS, respectively. The Phvul.001G246300 gene encodes an abscisic acid (ABA) receptor with pyrabactin resistance, PYR1-like (PYL) protein, which plays a central role in the crosstalk between ABA and jasmonic acid responses. Interestingly, our results also showed that the other defense genes were initially activated. These findings provide critical insights into the molecular mechanisms underlying plant defense against these diseases and could contribute to the development of more effective disease management strategies in the future.

Genetic Mapping for Agronomic Traits in IAPAR 81/LP97-28 Population of Common Bean (Phaseolus vulgaris L.) under Drought Conditions.

One of the significant challenges of common bean breeding is developing cultivars with high yields under drought conditions. The present study attempted to map quantitative trait loci (QTLs) and identify molecular markers that are linked to drought tolerance in the common bean. We evaluated 160 recombinant inbred lines (RILs), derived from the cross between the carioca cultivars IAPAR 81 (drought tolerant) and LP97-28 (susceptible to drought). In 2014 and 2015, two experiments were conducted (DS-drought stress, and NS-no drought stress). In the DS experiment, water suppression was performed at the flowering stages R5 to R6. The results of our experiments showed that drought conditions play an essential role in reducing most of the traits that were evaluated. RILs under drought conditions reduced the grain yield by 62.03% and 24% in 2014 and 2015, respectively. We identified 15 quantitative trait loci distributed on the chromosomes Pv01, Pv02, Pv03, Pv07, Pv08, Pv09, Pv10, and Pv11, related to grain yield, seed yield per day, 100-seed weight, number of pods per plant, plant height, number of days for flowering, and number of days to maturity. The characteristics of seed yield per day, 100-seed weight, and number of days to maturity showed that QTLs colocalized on Pv07. Identifying QTLs that are linked to drought tolerance in the RIL population IAPAR 81 × LP97-28 is of particular importance for common bean breeding programs seeking to improve carioca beans that are cultivated in regions with drought conditions, such as Brazil.

Genome-Environment Association Analysis for Bio-Climatic Variables in Common Bean (Phaseolus vulgaris L.) from Brazil.

Abiotic stress is a limiting factor for common bean (Phaseolus vulgaris L.) production globally. The study of the genotypic, phenotypic, and bio-climatic variables in a broad set of accessions may assist the identification of genomic regions involved in the climatic adaptation of the common bean. We conducted a genotyping-by-sequencing analysis using 28,823 SNPs on 110 georeferenced common bean accessions from Brazil to discover associations between SNPs and bio-climatic indexes. The population structure analysis clustered the accessions into two groups corresponding to the Andean and Mesoamerican gene pools. Of the 19 bioclimatic variables, 17 exhibited a significant association with SNPs on chromosomes Pv01, Pv02, Pv03, Pv04, Pv06, Pv09, Pv10, and Pv11 of common bean. Ten candidate genes were associated with specific bio-climatic variables related to temperature and precipitation. The candidate genes associated with this significant Pv09 region encode a Platz transcription factor family protein previously reported to be an essential regulator of drought stress. The SNP markers and candidate genes associated with the bio-climatic variables should be validated in segregating populations for water stress, which could further be used for marker-assisted selection. As a result, bean breeding programs may be able to provide advances in obtaining drought-tolerant cultivars.

Fine mapping of an anthracnose-resistance locus in Andean common bean cultivar Amendoim Cavalo.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is one of the world's most destructive diseases of common bean. The use of resistant cultivars is the most cost-effective strategy to manage this disease; however, durable resistance is difficult to achieve due to the vast virulence diversity of the anthracnose pathogen. Finding new genes with broad-spectrum resistance increases the prospect of designing an effective anthracnose-management strategy. Genetic analysis confirmed the presence of a single, dominant anthracnose-resistance locus in AC, which we provisionally named Co-AC. Bulk segregant analysis and genetic mapping of two F2 populations from the crosses AC × PI207262 and AC × G 2333 were used to determine the position of the Co-AC locus in a 631 Kbp genomic region flanked by the SNP markers SS56 and SS92 on the lower arm of chromosome Pv01. By genotyping 77 F3 plants from the AC × PI207262 cross using nine additional markers, we fine-mapped the Co-AC locus to a significantly smaller genomic region (9.4 Kbp) flanked by the SNP markers SS102 and SS165. This 9.4 Kbp region harbors three predicted genes based on the common bean reference genome, notably including the gene model Phvul.001G244300, which encodes Clathrin heavy chain 1, a protein that supports specific stomatal regulation functions and might play a role in plant defense signaling. Because the Co-AC resistance locus is linked in cis, it can be selected with great efficiency using molecular markers. These results will be very useful for breeding programs aimed at developing bean cultivars with anthracnose resistance using marker-assisted selection. This study revealed the broad-spectrum resistance of AC to C. lindemuthianum and the existence of the Co-AC anthracnose-resistance locus. Fine mapping positioned this locus in a small genomic region on the lower end of chromosome Pv01 that contained three candidate genes for the Co-AC locus.

Population Structure and Genetic Diversity of Sweet Cassava Accessions from the Midwestern, Southeastern and Southern Regions of Brazil

Abstract The objective of this work was to screen sweet cassava accessions collected in smallholding areas in the Midwestern, Southeastern and Southern regions of Brazil, using 15 SSR molecular markers, to determine population structure and genetic diversity. Polymorphism was detected in every loci analyzed, with mean of 6.33 alleles per locus, and mean polymorphism information content (PIC) of 0.6057, pointing out that the primers were highly informative. The observed heterozygosity ranged from 0.0709 (SSRY 101) to 0.9398 (GA 12), with a mean of 0.6511, and mean genetic diversity of 0.6578, ranging from 0.3592 (GA 136) to 0.8116 (SSRY 21). The most dissimilar combinations observed were BGM526PR-BGM596MS, BGM526PR-BGM622MS and BGM526PR-BGM629MS. The traditional cassava cultivars assessed were divided into four distinct groups: two with cultivars from the South, one from the Southeast and one from the Midwestern region of Brazil. The variances among and within groups determined by the analysis of molecular variance were 44 and 56%, respectively. The PhiPT parameter (analogue to Fst) of 0.44 indicates high differentiation among groups. Broad genetic diversity was found among the traditional sweet cassava cultivars assessed, and the most divergent groups were formed by cultivars from the South and the Midwestern regions of Brazil.

The common bean COK-4 and the Arabidopsis FER kinase domain share similar functions in plant growth and defence.

Receptor-like kinases are membrane proteins that can be shared by diverse signalling pathways. Among them, the Arabidopsis thaliana FERONIA (FER) plays a role in the balance between distinct signals to control growth and defence. We have found that COK-4, a putative kinase encoded in the common bean anthracnose resistance locus Co-4, which is transcriptionally regulated during the immune response, is highly similar to the kinase domain of FER. To assess whether COK-4 is a functional orthologue of FER, we expressed COK-4 in the wild-type Col-0 and the fer-5 mutant of Arabidopsis and evaluated FER-associated traits. We observed that fer-5 plants show an enhanced apoplastic and stomatal defence against Pseudomonas syringae. In addition, the fer-5 mutant shows reduced biomass, smaller guard cell size, greater number of stomata per leaf area, fewer leaves, faster transition to reproductive stage and lower seed weight per plant than the wild-type Col-0. Except for the stomatal complex length and number of stomata, COK-4 expression in fer-5 lines partially or completely rescued both defence and developmental defects of fer-5 to the wild-type level. Notably, COK-4 may have an additive effect to FER, as the expression of COK-4 in Col-0 resulted in enhanced defence and growth phenotypes in comparison with wild-type Col-0 plants. Altogether, these findings indicate that the common bean COK-4 shares at least some of the multiple functions of the Arabidopsis FER kinase domain, acting in both the induction of plant growth and regulation of plant defence.

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases.

KEY MESSAGE: Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F2:3 families from the Rudá (susceptible) × Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2 cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2 cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3 cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.

Genetics and mapping of a new anthracnose resistance locus in Andean common bean Paloma.

BACKGROUND: The Andean cultivar Paloma is resistant to Mesoamerican and Andean races of Colletotrichum lindemuthianum, the fungal pathogen that causes the destructive anthracnose disease in common bean. Remarkably, Paloma is resistant to Mesoamerican races 2047 and 3481, which are among the most virulent races of the anthracnose pathogen. Most genes conferring anthracnose resistance in common bean are overcome by these races. The genetic mapping and the relationship between the resistant Co-Pa gene of Paloma and previously characterized anthracnose resistance genes can be a great contribution for breeding programs. RESULTS: The inheritance of resistance studies for Paloma was performed in F2 population from the cross Paloma (resistant) × Cornell 49-242 (susceptible) inoculated with race 2047, and in F2 and F2:3 generations from the cross Paloma (resistant) × PI 207262 (susceptible) inoculated with race 3481. The results of these studies demonstrated that a single dominant gene confers the resistance in Paloma. Allelism tests performed with multiple races of C. lindemuthianum showed that the resistance gene in Paloma, provisionally named Co-Pa, is independent from the anthracnose resistance genes Co-1, Co-2, Co-3, Co-4, Co-5, Co-6, Co-12, Co-13, Co-14, Co-15 and Co-16. Bulk segregant analysis using the SNP chip BARCBean6K_3 positioned the approximate location of Co-Pa in the lower arm of chromosome Pv01. Further mapping analysis located the Co-Pa gene at a 390 kb region of Pv01 flanked by SNP markers SS82 and SS83 at a distance of 1.3 and 2.1 cM, respectively. CONCLUSIONS: The results presented here showed that Paloma cultivar has a new dominant gene conferring resistance to anthracnose, which is independent from those genes previously described. The linkage between the Co-Pa gene and the SS82 and SS83 SNP markers will be extremely important for marker-assisted introgression of the gene into elite cultivars in order to enhance resistance.

Genetic and Phytochemical Analysis to Evaluate the Diversity and Relationships of Mate (Ilex paraguariensis A.St.-Hil.) Elite Genetic Resources in a Germplasm Collection.

The aim of this study was to evaluate the phytochemical and genetic diversity, relationships and identification of mate (Ilex paraguariensis A.St.-Hil.) elite genetic resources belonging to the Brazilian germplasm collection and mate breeding program. Mate has been studied due to the presence of phytochemical compounds, especially methylxanthines and phenolic compounds. The samples were collected from the leaves of 76 mate elite genetic resources (16 progenies × 5 localities). Total DNA was extracted from mate leaves and 20 random primers were used for DNA amplification. Methylxanthines (caffeine and theobromine) and phenolic compounds (chlorogenic, neochlorogenic, and criptochlorogenic acids) were quantified by HPLC. The genetic divergence estimated was higher within (92%) than among (8%) the different populations. Analysis of genetic distance between origins provided the formation of two groups by UPGMA cluster analysis, with higher polymorphism (94.9%). The average content of caffeine ranged from 0.01 to 1.38% and theobromine of 0.10 - 0.85% (w/w). The caffeoylquinic acids concentrations (1.43 - 5.38%) showed a gradient 3-CQA > 5-CQA > 4-CQA. The coefficient of genetic variation (CVg) was of low magnitude for all mono-caffeoylquinics acids. Significant correlations (positive and negative) were observed between the phytochemical compounds. Genetic diversity analysis performed by RAPD markers showed a greater intra-populational diversity; genetic resources with low caffeine and higher theobromine content were identified and can be used in breeding programs; the correlation between methylxanthines and phenolic compounds can be used as a good predictor in future studies.

Linkage mapping of the Phg-1 and Co-1(4) genes for resistance to angular leaf spot and anthracnose in the common bean cultivar AND 277.

The Andean common bean AND 277 has the Co-1(4) and the Phg-1 alleles that confer resistance to 21 and eight races, respectively, of the anthracnose (ANT) and angular leaf spot (ALS) pathogens. Because of its broad resistance spectrum, Co-1(4) is one of the main genes used in ANT resistance breeding. Additionally, Phg-1 is used for resistance to ALS. In this study, we elucidate the inheritance of the resistance of AND 277 to both pathogens using F(2) populations from the AND 277 × Rudá and AND 277 × Ouro Negro crosses and F(2:3) families from the AND 277 × Ouro Negro cross. Rudá and Ouro Negro are susceptible to all of the above races of both pathogens. Co-segregation analysis revealed that a single dominant gene in AND 277 confers resistance to races 65, 73, and 2047 of the ANT and to race 63-23 of the ALS pathogens. Co-1(4) and Phg-1 are tightly linked (0.0 cM) on linkage group Pv01. Through synteny mapping between common bean and soybean we also identified two new molecular markers, CV542014(450) and TGA1.1(570), tagging the Co-1(4) and Phg-1 loci. These markers are linked at 0.7 and 1.3 cM, respectively, from the Co-1(4) /Phg-1 locus in coupling phase. The analysis of allele segregation in the BAT 93/Jalo EEP558 and California Dark Red Kidney/Yolano recombinant populations revealed that CV542014(450) and TGA1.1(570) segregated in the expected 1:1 ratio. Due to the physical linkage in cis configuration, Co-1(4) and Phg-1 are inherited together and can be monitored indirectly with the CV542014(450) and TGA1.1(570) markers. These results illustrate the rapid discovery of new markers through synteny mapping. These markers will reduce the time and costs associated with the pyramiding of these two disease resistance genes.

Genetic divergence in sweet cassava cultivars using morphological agronomic traits and RAPD molecular markers

In this work the genetic divergence among 14 sweet cassava cultivars was estimated by their morphological agronomic traits and RAPD molecular markers. The Tocher cluster analysis and the Nearest Neighbor Method were applied. The most dissimilar cultivars were Pão and Guaíra, Fécula Branca and Pão, and Pão and Caipira, while the most similar cultivar were the Fécula Branca and Branca 1, Branca 3 and Branca 1, and Guaíra and Branca 1. The Jaccard's coefficient showed that the most similar cultivars were Guaíra and Quarenta Quilos, while the most dissimilar were Branca 3 and Amarela da Rama Cinza. The divergence analysis indicated that promising crosses could be made between the Branca 3 cultivar and the Pão, Amarela 1, Fécula Branca and Amarela 2 cultivars for the high genetic divergence, favorable agronomic and culinary traits, and disease resistance on the part of at least one of the parents involved in the cross.

A divergência genética entre 14 cultivares de mandioca-de-mesa foi estimada mediante o uso de caracteres morfoagronômicos e de marcadores moleculares RAPD. As análises de agrupamento de Tocher e do Vizinho Mais Próximo foram efetuadas. As cultivares mais divergentes foram Pão e Guaíra, Fécula Branca e Pão, e Pão e Caipira, enquanto as mais similares foram Fécula Branca e Branca 1, Branca 3 e Branca 1, e Guaíra e Branca 1. O coeficiente de Jaccard indicou que as cultivares mais similares foram Guaíra e Quarenta Quilos, enquanto as mais dissimilares foram Branca 3 e Amarela da Rama Cinza. A análise de divergência indicou que cruzamentos promissores deveriam ser efetuados entre as cultivares Branca 3, Pão, Amarela 1, Fécula Branca e Amarela 2 pela alta divergência genética, características agronômicas e culinárias favoráveis, e resistência à doenças de parte de pelo menos um dos parentais envolvidos no cruzamento.

Parasexuality in Race 65 Colletotrichum lindemuthianum isolates.

Heterokaryosis is the initial step of the parasexual cycle, a process that provides genetic variability in filamentous fungi through the production of heterozygous diploid nuclei. To characterize the parasexual cycle in Colletotrichum lindemuthianum, we evaluated the presence of heterokaryosis, vegetative compatibility reactions, and diploid formation among isolates of Race 65 collected from different Brazilian states. Vegetative compatibility groups were identified among the isolates according to their ability to form heterokaryons. Two heterozygous diploids were selected from compatible heterokaryons, which were characterized by the segregation of the parental auxotrophic markers and by RAPD profiles.

Comparison of methods for phenotypic stability analysis of cassava (Manihot esculenta Crantz) genotypes for yield and storage root dry matter content

The objective of this work was to compare different phenotypic stability methods by using yield and storage root dry matter content data of eight cassava genotypes, assessed in eight environments in northwest of Paraná State, Brazil. All the methodologies applied showed to be able to study the stability of cassava genotypes, but each with its peculiarities. The methodologies of Eskridge, Annicchiarico and Lin and Binns were the most appropriated on situation with smaller effect of G x E interaction. The AMMI analysis and the Toler and Burrows methodology were the most specific on detailing specific adaptations of cassava genotypes to favorable and unfavorable environments. It could be suggested to use simultaneous AMMI analysis and Toler and Burrows methodology. The clone IAC 190-89 was the most promising.

O objetivo deste trabalho foi comparar diferentes metodologias de análise de estabilidade fenotípica considerando produção e teor de matéria seca nas raízes tuberosas de oito genótipos de mandioca, avaliados em oito ambientes na região Noroeste do Paraná. Todas as metodologias aplicadas se mostraram aptas no estudo da estabilidade dos genótipos avaliados, cada uma delas com suas particularidades. As metodologias de Eskridge, Annicchiarico e Lin e Binns se mostraram mais adequadas para situações de menor efeito da interação G x A. A análise AMMI e a metodologia de Toler e Burrows propiciaram um melhor detalhamento das adaptações específicas dos genótipos a ambientes favoráveis e desaforáveis. É sugerido o uso simultâneo da análise AMMI e da metodologia de Toler e Burrows. O clone IAC 190-89 mostrou-se mais promissor.

Dry matter production and distribution in three cassava (Manihot esculenta Crantz) cultivars during the second vegetative plant cycle

A study was carried out in Araruna County, State of Paraná, to understand the relationship between the total dry matter yield and its proportion allocated to the storage roots of cassava (Manihot esculenta Crantz) plants in the second vegetative cycle. The experimental design was a randomized complete block in split-plot scheme with four replications. The plots consisted of the Mico, IAC 13 and IAC 14 cultivars and the monthly harvesting dates were assessed in the sub-plots. The results showed that the Mico and IAC 13 cultivars were more efficient in allocating dry matter to the storage roots. The IAC 14 cultivar allocated a higher proportion of assimilates to stems compared with the other two cultivars. With regard to the influence of harvesting time, the lowest harvest indexes were observed in the periods of more intense vegetative growth. However, the highest carbohydrate proportions were allocated to the storage roots during periods of low vegetative growth.

Com o objetivo de uma melhor compreensão da relação entre a produtividade total de massa seca e a proporção de alocação desta nas raízes tuberosas em plantas de mandioca, foi conduzido no município de Araruna-PR, um experimento em delineamento de blocos casualizados, em esquema de parcelas subdivididas com quatro repetições. Nas parcelas foram dispostas três cultivares (Mico, IAC 13 e IAC 14), e nas subparcelas dez épocas de colheita mensais, a partir do início do segundo ciclo vegetativo das plantas. As cultivares Mico e IAC 13 foram mais eficientes do que a IAC 14 em alocar massa seca nas raízes tuberosas, ao passo que esta última alocou maior proporção de massa seca em suas hastes. Em relação às épocas, os menores índices de colheita ocorreram em períodos de mais intenso crescimento vegetativo das plantas, ao passo que a maior proporção de carboidratos foi alocada nas raízes tuberosas em períodos de baixo crescimento vegetativo.

Characterization of Colletotrichum lindemuthianum isolates using differential cultivars of common bean in Santa Catarina State, Brazil

In 2003 and 2004, 32 isolates of Colletotrichum lindemuthianum obtained from the infected plants of field-grown common bean (Phaseolus vulgaris L.) in Santa Catarina state, Brazil were analyzed based on the virulence to 12 differential cultivars of Phaseolus vulgaris L.. Thirteen distinct races were identified, six of which had not been reported previously in Santa Catarina. This is the first report of the occurrence of 67, 83,101,103,105, and 581 races of C. lindemuthianum. Race 65 was most common (34 percent). All the isolates were compatible to the cultivars Michelite and Mexico 222. Some isolates infected not only differential cultivar of Mesoamerican origin, but also the ones of Andean origin.

Em 2003 e 2004, isolados de Colletotrichum lindemuthianum obtidas de plantas infectadas de feijoeiro comum (Phaseolus vulgaris L.) no Estado de Santa Catarina, Brasil foram analisadas baseando-se na virulência em 12 cultivares diferenciadoras de Phaseolus vulgaris L.. Treze raças distintas foram identificadas, sendo que seis delas não haviam sido reportadas anteriormente em Santa Catarina. Este é o primeiro registro de ocorrência das raças 67, 83, 101,103,105, e 581 do C. lindemuthianum. A raça mais comum foi a 65 (34 por cento). Todos os isolados foram compatíveis com as cultivares Michelite e México 222. Alguns dos isolados infectaram tanto cultivares diferenciadoras de origem Mesoamericana como de origem Andina.

Estabilidade produtiva de cultivares de mandioca-de-mesa coletadas no Estado do Paraná / Yield stability of sweet cassava cultivars from Paraná State

O presente trabalho teve como objetivo avaliar a estabilidade de produção de raízes tuberosas e de índice de colheita de 14 cultivares de mandioca-de-mesa coletadas no Estado do Paraná. Os experimentos foram instalados nos municípios de Maringá (2001/2002 e 2002/2003) e de Campo Mourão (2003/2004 e2004/2005), região Noroeste do Paraná, perfazendo um total de quatro ambientes. O delineamento experimental utilizado foi o de blocos completos casualizados, com três repetições. A estabilidade foi avaliada por meio das metodologias propostas por Lin e Binns, Eskridge e Annicchiarico. Em geral, as cultivares Caipira, Fécula Branca e Amarela 2 mostraram-se mais estáveis e apresentaram elevadas médias de produção de raízes tuberosas e de índice de colheita. Estas cultivares são boas indicações para cultivo na região Noroeste do Paraná também pelos baixos níveis de HCN, reduzido tempo de cozimento e boa resistência às doenças.

The objective of this work was to study the storage roots yield and harvest index stability of 14 sweet cassava cultivars collected from Paraná State. Trials were carried out in Maringá (2001/2002 and 2002/2003) and Campo Mourão (2003/2004 and 2004/2005) counties, Northwest region of Paraná State, makinga total of four environments. Randomized complete blocks design with three replications was used. Thestability was evaluated according methods proposed by Lin e Binns, Eskridge and Annicchiarico. The Caipira, Fécula Branca and Amarela 2 cultivars were the most stable cultivars and showed high storage roots yield and harvest index averages. These cultivars may be a good crop choice in Northwestern region of Paraná State because they also presented low content of HCN, fast cooking time and high level of diseases resistance.

Genetic control on the performance of common bean differential cultivars to Colletotrichum lindemuthianum races

The aim of this work was to perform genetic control on differential cultivars Michelite, Michigan Dark Red Kidney, Perry Marrow, Cornell 49-242, PI 207262, AB 136 and G 2333 and its diallel hybrids by using Hayman's methodology. The entire F1s populations were evaluated in relation to race 89, whereas the race 31, the diallel scheme did not include the cultivar G 2333. The results showed that the additive effects were predominant for the 31 race, while non-additive effects were more important for race 89. The results demonstrated a high coefficient of genetic determination for the race 31. The G 2333, AB 136 and PI 207262 cultivars should be recommended obtaining cultivar resistant to anthracnose by backcross programs because theyshowed the highest proportion of resistant dominant alleles for the races 31 and 89.

Dentre as várias doenças que causam problemas no cultivo de feijão comum (Phaseolus vulgaris L.), uma das mais importantes é a antracnose causada pelo fungo Colletotrichum lindemuthianum (Saac. et Magn.) Scrib., a qual pode resultar em severas perdas na produtividade de grãos. O controle genético, nas cultivares diferenciais Michelite, Michigan Dark Red Kidney, Perry Marrow, Cornell 49-242, PI 207262, AB 136 e G 2333 e seus 21 híbridos dialélicos, foi obtido usando a metodologia de Hayman (1954). Todas as populações F1s foram avaliadas em relação à raça 89, enquanto que os híbridos envolvendo a cultivar G 2333 não foram avaliados com a raça 31. Os resultados demonstraram que os efeitos aditivos foram predominantes para a raça 31, enquanto os efeitos gênicos não aditivos foram mais importantes na reação de incompatibilidade das cultivares a raça 89. Os resultados ainda evidenciaram um elevado coeficiente de determinação genética para a raça 31. Os cultivares G 2333, AB 136 e PI 207262 são os mais indicados para programas de melhoramento visando à obtenção de cultivares resistentes à antracnose por possuírem maior proporção de alelos dominantes para resistência às raças 31 e 89.

Genetic divergence of the common bean (Phaseolus vulgaris L.) group Carioca using morpho-agronomic traits by multivariate analysis.

The objective of this study was to evaluate the genetic divergence among the common bean group Carioca by the Tocher method (based on Mahalanobis distance) and graphic dispersion of canonic variables, aiming to identify populations with wide genetic variability. Eighteen genotypes were evaluated in four seasons using a randomized block design with four replications. The mean weight of 100 seeds, in three experiments, and the mean number of pods per plant, in one experiment, were the most important characteristics for the genetic divergence, representing more than 46% of the total variation in the first canonic variable. The first two canonic variables were sufficient to explain about 88.23% of the total variation observed in the average of the four environments. The results showed that CNFC 8008 and CNFC 8009 genotypes presented the best yield averages in all the experiments. While Pérola, Princesa and CNFC 8005 cultivars were the most dissimilar for morpho-agronomic traits. Therefore, the combinations of PérolaxCNFC 8008, CNFC 8005xCNFC 8009, PérolaxCNFC 8009, PrincesaxCNFC 8008 and PrincesaxCNFC 8009 were indicated for interpopulational breeding.