Controle genético da incompatibilidade do cruzamento entre cultivares andinas e mesoamericanas de feijoeiro comum

Abstract

RESUMONormalmente, ocorre incompatibilidade nos cruzamentos entre feijoeiros de origem andina com mesoamericanas. Há dúvidas no controle genético do caráter. Singh & Gutiérrez (1984) relataram que no controle do caráter estão envolvidos dois genes e ocorre epistasia recessiva dupla. Vilarinho (2004) apresentou resultados, relatando que não seriam apenas dois genes. Para melhor elucidar o controle genético desse caráter foi realizado o presente trabalho. Para isso, a cultivar de origem andina Jalo EEP 558 foi cruzada com a Small White , que é mesoamericana, porém compatível com a anterior. A cultivar de origem mesoamericana Mulatinho da Vagem Roxa também foi cruzada com a Small White . As gerações F 1 desses dois híbridos foram cruzadas entre si. As sementes resultantes foram semeadas no campo e avaliada a ocorrência ou não da incompatibilidade. Constatou-se a segregação de três plantas normais para uma incompatível. Esse resultado evidencia que são dois genes, DL 1 e DL 2 , e que o genótipo das cultivares envolvidas são: Jalo EEP 558 dl 1 dl 1 DL 2 DL 2 ; Mulatinho da Vagem Roxa DL 1 DL 1 dl 2 dl 2 ; Small White dl 1 dl 1 dl 2 dl 2 .Termos para indexação: Phaseolus vulgaris L., epistasia, genes. ABSTRACTCrosses between Andean and Mesoamerican common beans are usually incompatible. There are doubts about the genetic control of the trait. Singh & Gutiérrez (1984) reported that two genes are involved in the trait control and that double recessive epistasis occurs. On the other hand, Vilarinho (2004) presented results indicating that more than two genes are involved. The present study was carried out to clarify the genetic control of this trait. For this purpose, the Andean cultivar Jalo EEP 558 was crossed with Small White , which is Mesoamerican, but compatible with the former one. The Mesoamerican cultivar Mulatinho da Vagem Roxa was also crossed with Small White . The F 1 generation of these two hybrids was crossed with each other. The resulting seeds were sown on the field and the occurrence of incompatibility was evaluated. Segregation of 3 (normal) to 1 (incompatible) plants was observed, indicating that there are two genes, DL 1 and DL 2 , as reported by Singh & Gutiérrez (1984), and that the genotype of the cultivars involved are: Jalo EEP 558 dl 1 dl 1 DL 2 DL 2 ; Mulatinho da Vagem Roxa DL 1 DL 1 dl 2 dl 2 ; Small White dl 1 dl 1 dl 2 dl 2 .

Escolha de genitores quanto à precocidade e produtividade de feijão tipo carioca

“…Grande parte das fontes de genes quanto à precocidade estão em feijões de origem andina (Welsh et al, 1995), e grãos com padrão comercial, de modo geral, são de origem mesoamericana. Em alguns cruzamentos entre os dois conjuntos gênicos, observa-se incompatibilidade, o que inviabiliza ou causa diversas anormalidades nas plantas F 1 , tais como nanismo, folhas cloróticas, esterilidade, crescimento radical reduzido e formação de raízes adventícias no hipocótilo (Arantes et al, 2008).…”

Análise genética do caráter nuda em panículas de aveia hexaplóide

“…According to Ougham et al (1996), the N 1 allele has an effect on lignin deposition The presence of hulled grains in homozygous genotypes (N 1 N 1 N 2 N 2 ) may also be associated with incomplete penetrance and/or variable expressiveness of the genes; i.e., the genotype has the gene which exhibits the naked characteristic; nevertheless, the frequency of expression of the phenotype is less than 100%, as was observed in the naked parental genotype and in other studies of this trait in oats (Valentine 1995, Cabral et al 2000. In this sense, alteration in the expected segregations may be attributed to differences in the penetrance and expressiveness of the genes as a result of the environmental effect (Arantes et al 2008).…”

Implications of mitotic and meiotic irregularities in common beans (Phaseolus vulgaris L.)

“…However, the generation of higher genetic diversity by crossing Andean and Mesoamerican cultivars in several situations is not possible due to the occurrence of genetic incompatibility in the F 1 plants (Vieira et al, 2005). This incompatibility is manifested by dwarfism or weakness in the F 1 hybrid, whose plants die or have poor growth, and exhibit a number of changes including sterility, reduced root growth, chlorotic leaves, absence of roots, and the formation of adventitious roots on the hypocotyl region (Vilarinho et al, 2004;Vieira et al, 2005;Arantes et al, 2008).…”

“…In the F1 generation, the genotype would be DL 1 dl 1 DL 2 dl 2 , and the presence of dominant alleles of the two genes would lead to incompatibility. However, Arantes et al (2008) observed that the 'incompatibility' trait has a very variable expression, and there is variation in the plant development stage in which the symptoms manifest.…”