RESUMO
The development of in vitro haploid plants followed by spontaneous or induced genome duplication allows to achieve, in one generation, the recovery of total homozygosis. The efficiency of the haplodiploidization process through in vitro anther culture of barley is variable among genotypes. This study was aimed at determining the androgenetic response of nine barley genotypes from the breeding program of Embrapa Trigo, analysing proembryoid development and green plantlets regeneration in anthers cultivated in vitro. Cultivar 'BR2' presented the highest average of proembryoids (104/anther) and 'MN698' presented the highest average of green plantlets (0,41/anther). There was a significant variation among the average values of barley genotypes for embryo formation and green plantlets regeneration, making possible the selection to combine androgenetic capacity and good agronomic traits.
A obtenção, na cevada, de plantas haplóides in vitro e a posterior duplicação natural ou artificial do genoma permitem alcançar a homozigose completa, em uma geração. A eficiência da haplodiploidização pela cultura de anteras é variável entre os genótipos. Foi avaliada a resposta androgenética através da formação de pró-embrióides e da regeneração de plântulas verdes em nove cultivares do programa de melhoramento de cevada da Embrapa Trigo, em anteras cultivadas in vitro. A cultivar "BR2" apresentou maior média de pró-embrióides (104/antera), enquanto "MN698" mostrou a maior média de plântulas verdes (0,41/antera). Houve variação significativa entre os valores médios dos genótipos em relação à formação de pró-embrióides e à regeneração de plântulas verdes, indicando a possibilidade de seleção para combinar a capacidade androgenética com boas características agronômicas.
RESUMO
A genetic analysis of adult plant resistance to leaf rust (Puccinia triticina) was performed in in vitro obtained double haploid progenies from a cross between the Brazilian wheat cultivar Trigo BR 35, which, under the high inoculum pressure of the southern region, has been resistant to leaf rust for more than 12 years, and the susceptible cultivar IAC 13-Lorena. Haplodiploidization via in vitro gimnogenesis was done by somatic elimination of the pollen donor genome after maize pollination of the F1 plants. The advantages and usefulness of double haploids (DH) for genetic analysis of complex inherited traits like durable adult-plant resistance to wheat leaf rust were evident: it was possible to analyze inheritance patterns in this cross by using only the 35 DH homozygous segregant lines obtained by in vitro embryo culture of F1 flowers pollinated by maize, this number being equivalent to 1,225 conventional F2 lines because of lack of heterozygosity. After being infected with MCG and LPG races, the results indicated that Trigo BR 35 has two resistance genes. One of the genes expressed resistance only after the intermediate stage of plant development (5-6 leaves).