Linkage mapping of the Phg-1 and Co-14 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-14 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-14 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 F2 populations from the AND 277 × Rudá and AND 277 × Ouro Negro crosses and F2:3 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-14 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, CV542014450 and TGA1.1570, tagging the Co-14 and Phg-1 loci. These markers are linked at 0.7 and 1.3 cM, respectively, from the Co-14/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 CV542014450 and TGA1.1570 segregated in the expected 1:1 ratio. Due to the physical linkage in cis configuration, Co-14 and Phg-1 are inherited together and can be monitored indirectly with the CV542014450 and TGA1.1570 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

Sociedade Brasileira de Melhoramento de Plantas Crop Breeding and Applied Biotechnology

ABSTRACT Genetic resistance in common bean (Phaseolus vulgaris L.) is the most effective control of anthracnose caused by Colletotrichum lindemuthianum (Sacc. et Magnus) Lams.-Scrib. In a previous report, two genetic symbols, Q and B, were assigned to describe the gene(s) controlling the resistance of the cultivar AB 136 to races 31 and 69 of the pathogen, respectively. In the present study, progeny tests with two identical sets of F 2:3 population were used to obtain the first experimental evidence whether one single gene controls the resistance to both races 31 and 69. The absence of recombinations between the putative genes (Q and B) allowed the conclusion that a single dominant gene controls the resistance of the cultivar AB 136 to both races 31 and 69. The symbol Co-6 was assigned to the gene. In addition, linkage analysis with RAPD marker indicated that Co-6 also controls the resistance of AB 136 to other races of the pathogen, or that different genes are present in the same linkage block

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

Inheritance of resistance to races 69 and 453 of Colletotrichum lindemuthianum in the common bean

The cultivars, AB 136 and G 2333 both resistant to Colletotrichum lindemuthianum races 69 and 453, were crossed with the cultivars Michelite and Perry Marrow (susceptible to both races), with Dark Red Kidney and Cornell 49242 (resistant to both races) and F1 and F2 generations were obtained. Plants were inoculated using a spore suspension at 1.2 x 10(6) concentration. The reaction of F1 and F2 populations showed that Dark Red Kidney, Cornell 49242 and AB 136 cultivars had the dominant genes A (Co-1), Are (Co-2) and Co-6, respectively, was conferring resistance to races 69 and 453. The segregation data obtained from F2 populations indicated that G 2333 carried two dominant resistance genes Co-5 gene and another one Co-7 for 69 and 453 races. The dominant genes in G 2333 and its resistance to C. lindemuthianum race could be transferred to provide anthracnose resistance to susceptible cultivars relatively easy.<br>Os cultivares AB 136 e G 2333 ambos resistentes às raças 69 e 453 de Colletotrichum lindemuthianum foram cruzados com os cultivares Michelite e Perry Marrow (suscetíveis à ambas as raças) e com Dark Red Kidney e Cornell 49242 (resistentes à ambas as raças) e, obtidas as gerações F1 e F2. As plantas foram inoculadas com uma suspensão de esporos, utilizando-se uma concentração de 1,2 x 10(6) esporos/ml de água. As reações das populações F1 e F2 evidenciaram que os cultivares Dark Red Kidney; Cornell 49242 e AB 136 possuem, respectivamente, os genes dominantes A (Co-1) Are (Co-2) e Co-6, os quais conferiram a resistência às raças 69 e 453. Os dados de segregação obtidos nas populações F2 indicaram que G 2333 carrega os genes dominantes de resistência Co-5 e Co-7. Os genes dominantes presentes em G 2333 e sua resistência às raças de C. lindemuthianum, poderão serem transferidos para cultivares suscetíveis com relativa facilidade

Esterase polymorphism marking cultivars of Manihot esculenta, Crantz

Esterase isozymes were used to detected substrate-preference polymorphism in twenty cultivars of Manihot esculenta, and to show cultivar-specific variation of this species. A relatively complex extraction solution of proteins from leaves was needed to show a larger number of esterase isozymes. Similarity between cultivars from six groups ranged from 51 to 96%. The cultivars identified by the same name seemed to be biochemically different regarding esterase isozymes. Esterase isozyme electrophoretic patterns could, therefore, be used to discriminate the cultivars identified by the same name, and to monitor the vegetative propagation of cultivars maintained in the germplasm collection. In breeding strategies, isoesterase analysis could be used to avoid intercrossing between the similar genotypes.<br>Isoenzimas esterases foram usadas no presente estudo, para detectar polimorfismos específicos para diferentes substratos em vinte cultivares de Manihot esculenta, e para mostrar variações específicas de cultivares nesta espécie. Os diferentes cultivares de M. esculenta tem sido mantidos na coleção de germoplasma do Departamento de Agronomia da Universidade Estadual de Maringá (Maringá, PR), e foram provenientes de cultivares tradicionais coletados nas regiões sudoeste e noroeste do Estado. Foi necessário a utilização de uma solução de extração de proteínas relativamente mais complexa, para evidenciar um maior número de isoenzimas esterases. A similaridade entre os cultivares variou de 51 a 96%. Cultivares identificados pelo mesmo nome parecem ser bioquimicamente diferentes para as isoenzimas esterases. Os padrões eletroforéticos das isoesterases podem, portanto, serem usados para discriminar os cultivares que são identificados pelo mesmo nome, e para monitorar a propagação vegetativa dos cultivares mantidos na coleção de germoplasma. A análise das isoesterases pode também ser usada para evitar cruzamentos entre genótipos mais similares em programas de melhoramento

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.<br>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