Inheritance of reaction to Leveillula taurica (Lev.) Arn. in Capsicum annuum L.

Abstract

The use of fungicides to control powdery mildew in sweet pepper has been ineffective and genetic resistance is the best alternative. Resistance sources identified in Capsicum annuum L. are rare and unsatisfactory. The purpose of this work was to study the inheritance of C. annuum reaction to powdery mildew. Three homozygous powdery mildew resistant parents, HV-12, Chilli and #124 and three susceptible lines, 609, 442 and 428 were used to obtain seven F 1 's and respectively their generations F 2 : HV-12 x 609, 442 × HV-12, 428 × HV-12, Chilli × 609, #124 × 609, Chilli × HV-12 and #124 × HV-12. The powdery epidemic was natural using inoculum from highly sporulating susceptible pepper host. Powdery mildew host reaction evaluations were carried out during the fruit production using a rating system based on disease severity scales varying from 1 (resistant) to 5 (highly susceptible). The experimental design was completely randomized. The following genetic parameters were estimated: locus numbers, gene action, heritability coefficient, expected selection gain and observed progress in F 3 generation, and possibly allelic relationship among resistance genes of different resistance sources. The HV-12 × 609 cross was the only one that showed absence of dominance. Other genetically analyzed crossings showed dominant and epistatic effects. Resistance was characterized as being due to at least four pairs of genes. The heritability and selection gains estimates were high. The resistance mechanisms of #124, Chilli and HV-12 showed differences in their expression. Key words: sweet pepper, powdery mildew, genetic resistance, gene action, allelism HERANÇA DA REAÇÃO À Leveillula taurica (LEV.) ARN.EM Capsicum annuum L.RESUMO: O uso de fungicidas no controle do oídio do pimentão tem se mostrado ineficaz, sendo a resistência genética a melhor alternativa. As fontes de resistência identificadas em Capsicum annuum L. são raras e não satisfatórias. O objetivo deste trabalho foi estudar a herança da reação de C. annuum ao oídio. Três progenitores resistentes e homozigóticos, HV-12, Chilli e #124 e três suscetíveis, 609, 442 e 428 foram usados na obtenção de sete híbridos e respectivas gerações F 2 : HV-12 × 609, 442 × HV-12, 428 × HV-12, Chilli × 609, #124 × 609, Chilli × HV-12 e #124 × HV-12. A epidemia de oídio ocorreu de maneira natural a partir de inóculo mantido em plantas de pimentão suscetíveis. As avaliações das reações ao oídio foram feitas na fase de frutificação, através de uma escala de notas de 1 (resistente) a 5 (altamente suscetível). O delineamento experimental utilizado foi inteiramente casualizado. Foram estimados, os números de locos, ação gênica, coeficiente de herdabilidade, ganho de seleção esperado e o progresso observado em F 3 e possíveis relações de alelismo entre os genes que governam a resistência. O cruzamento HV-12 × 609 foi o único em que a reação de resistência mostrou ausência de dominância. Nos demais cruzamentos detectaram-se efeitos dominantes e epistáticos. A herança foi caracterizada send...

Hot pepper (Capsicum chinense, Jacq.) inheritance of reaction to powdery mildew

“…The best control practice would be by resistant varieties. Heredity studies of C. annuum showed that resistance to powdery mildew is controlled by three genes with additive as well as epistatic effects (Shifriss et al, 1992, Daubeze et al, 1995, Blat et al, 2005b. Murthy & Deshpande (1997) found resistance to be dominant and polygenic.…”

Identification of sequence-characterized amplified regions (SCARs) markers linking resistance to powdery mildew in chilli pepper (Capsicum annuum L.)

“…The high heritability of disease resistance shows that the powdery mildew infection reaction in general is not so much influenced by environmental conditions. It was also observed by Blat et al (2005).…”

“…Shifriss et al (1992) showed that, the disease resistance expression in doubled-haploid variety HV-12 was due to the restriction in pathogen infection, its colonization and leaf defoliation. The inheritance of resistance to powdery mildew in C. annuum involves several loci, which demand stronger selection in generations to get homozygosity (Blat et al, 2005). The mode of inheritance for powdery mildew resistance in chilli pepper is complex and inheritance study has also indicated dominant type of resistance to powdery mildew (Anand et al, 1987).…”

Growth regulators and darkness increase efficiency in in vitro culture of immature embryos from peppers

“…Because of that, this crop is subjected to huge breeding efforts to ensure yield stability and fruit quality (Blat et al, 2005;Crosby, 2008;de Sousa and Maluf, 2003). In this regard, in vitro culture of immature embryos can be useful for shortening generation cycles, producing haploids and double haploids, or rescuing potentially abortive interspecific embryos, which enables the introgression of genes between related species (Bhattarai et al, 2009;Guzzo et al, 2004;Hossain et al, 2003;Lotfi et al, 2003;Yoon et al, 2006).…”