A review of angular leaf spot resistance in common bean.

Angular leaf spot (ALS), caused by Pseudocer-cospora griseola, is one of the most devastating diseases of common bean (Phaseolus vulgarisL.) in tropical and subtropical production areas. Breeding for ALS resistance is difficult due to the extensive virulence diversity of P. griseolaand the recurrent appearance of new virulent races. Five major loci, Phg-1 to Phg-5, confer-ring ALS resistance have been named, and markers tightly linked to these loci have been reported. Quantitative trait loci (QTLs) have also been described, but the validation of some QTLs is still pending. The Phg-1, Phg-4, and Phg-5loci are from common bean cultivars of the Andean gene pool, whereas Phg-2 and Phg-3are from beans of the Mesoamerican gene pool. The reference genome of common bean and high-throughput sequencing technologies are enabling the development of molecular markers closely linked to the Phg loci, more accurate mapping of the resistance loci, and the compar-ison of their genomic positions. The objective of this report is to provide a comprehensive review of ALS resistance in common bean. Further-more, we are reporting three case studies of ALS resistance breeding in Latin America and Africa. This review will serve as a reference for future resistance mapping studies and as a guide for the selection of resistance loci in breeding programs aiming to develop common bean cultivars with durable ALS resistance

Diversidade genética de Chenopodium ambrosioides da região cacaueira da Bahia com base em marcadores RAPD Genetic diversity based on RAPD markers of Chenopodium ambrosioides from the cocoa region of Bahia State, Brazil

Chenopodium ambrosioides L., conhecida no Brasil por suas propriedades medicinais e usada principalmente para o controle de verminoses intestinais, é pouco estudada quanto à diversidade genética. O objetivo deste trabalho foi avaliar a diversidade genética de 16 indivíduos de C. ambrosioides, provenientes de diferentes municípios da região cacaueira da Bahia, pela técnica de RAPD (DNA polimórfico amplificado ao acaso). Apenas 6,9% das 216 bandas RAPD amplificadas foram polimórficas e a análise de agrupamento evidenciou que não há formação de grupos por área de coleta. Portanto, há pequena variabilidade entre os materiais e esta variabilidade encontra-se distribuída entre as regiões amostradas.<br>Chenopodium ambrosioides L. is known in many parts of Brazil for its medicinal properties, mainly used to control intestinal worms. Its genetic diversity is little studied. The objective of this work was to evaluate the genetic variability of 16 accessions of C. ambrosioides from the cocoa region of Bahia State, Brazil, by the RAPD technique (Random Amplified Polymorphic DNA). Only 6.9% of the 216 amplified RAPD bands were polymorphic and the pattern of dispersion of individuals showed no clustering related to sample site. Therefore, there is low variability among accessions and it is distributed among the accessions from the entire sampled region

Marcadores microssatélites relacionados com a resistência à vassoura-de-bruxa do cacaueiro Microsatellite markers related to resistance of cocoa tree against witches'-broom

Os objetivos deste trabalho foram caracterizar a resistência à vassoura-de-bruxa de plantas de cacau originadas do cruzamento entre TSH 1188 e CCN 51 (população segregante), por meio de dois métodos de inoculação em condições de campo, e identificar marcadores microssatélites específicos para grupos de plantas resistentes e suscetíveis. As plantas-controle avaliadas pelos métodos de inoculação natural e inoculação artificial em campo produziram os mesmos padrões de sintomas. As plantas da população segregante também coincidiram os padrões de sintomas em 90%, por esses dois métodos. O método de inoculação artificial em campo permite detectar falso-resistentes. Dos 18 pares de primers microssatélites amplificados, 15 foram polimórficos entre os genitores, e seis entre os grupos de plantas segregantes contrastantes quanto à resistência à vassoura-de-bruxa. Foram confirmadas três marcas previamente associadas a QTL (locos para características quantitativas) relacionados com a resistência à vassoura-de-bruxa, comuns a outras populações. Também foram identificados três novos QTL para esta característica, típicos desta população, o que comprova sua utilidade para o melhoramento genético do cacaueiro.<br>The objectives of this work were to evaluate cocoa tree resistance against witches'-broom, in plants originated from the crossing between TSH 1188 and CCN 51 (segregating population), by means of two methods of inoculation in field conditions, and to identify microsatellite markers specific for resistant and susceptible plants. The control plants bore identical symptoms as the plants of the segregating population in 90% of the cases under the two methods. The method of artificial inoculation in the field allows the detection of false resistance to the disease. Of the 18 pairs of microsatellite primers amplified, 15 were polymorphic between genitors and six were polymorphic between the two groups of plants evaluated for resistance to witches'-broom. Three previously characterized markers were confirmed as associated to QTL (quantitative trait loci) related to resistance to the witches'-broom, which is common in other populations. Three new QTL for this characteristic, typical of this population, were also identified, which proves the utility of this population for cocoa breeding