Suplemento. Edição dos resumos do 41º Congresso Nacional de Genética, Caxambu, MG, 1995

SANTOS, F. G. dos

VASCONCELOS, M. J. V. de

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A.138USE OF RFLPs TO IDENTIFY GENES FOR ALUMINUM TOLERANCE IN MAIZE. Giovana A.Torres'; Maurício A, Lopes2; Sidney N, Parentonf and Edilson Paiva2, 1)Depto, de Biologia - UFLA,Lavras, MG, 2) CNPMS/EMBRAPA, CP 151, 35701-970, Sete Lagoas - MG.The objective of this study is to identify RFLP markers linked to QTLs that control A! tolerance inrnaize. The genetic material utilized consists of an F2 population derived from a cross between the AI-susceptible line L53 and AI-tolerant line L1327. Both lines have been developed by the maizebreeding program of the National Maize and Sorghum Research Center - CNPMS/EMBRAPA. Thestrategy used was Bulked Segregant Analysis (BSA), which is based on choosing homozygous F2individuais for bulking. The index Relative Seminal Root Length (RSRL) was used as the phenotypicmeasure of AI tolerance. The frequency distribution of RSRL showed continuos distribution for RSRL,with skewing towards AI-susceptible individuais, The estimated heritability for the trait [(0'2 F2 - 0'2 E)/0'2 F2l was found to be 60%. This moderately high heritability value suggests that although thecharacter is of quantitative nature, it may be controlled by a small number of qenes. Seedlings of theF2 population which scored the highest and the lowest values for RSRL were subsequently selfed toobtain F3 families. These families were evaluated in nutrient solution to identify the ones that weren'tsegregating. Based on the average and the genetic variance of these families, 5 individuais werechosen for each bulk, Ninety two probeswere selected at an average interval of 30 cM covering alithe ten maize chrornosornes. DNA was digested with Eco RI, Bam HI and Hindlll. For ourhybridization work, a nonradioactive labeling system, using dig-dUTP and alkaline phosphatase,proved to be quite efficient and reliable, resulting in Southern blots with good resolution and allowingthe membranes to be stripped and reprobed at least three times, Thirty three markers showedcodominant effect identifying 56 RFLP loci, that could distinguish the parental lines. These 33 probeswere nybridízed with DNA from the two contrasting butks. We identified three RFLPs (two at chrom. 8and one at the chrom. 2) that could distinguish the bulks. The linkage will be confirmed by segregationanalysis in the F2 population. Also, other informative markers are being searched in order to increasegenome coverage and saturate the regions probably linked to the QTLs.Financial support: CNPMS, FAPEMIG, IAEA.A.139ESTUDO DA VARIABILIDADE GENÉTICA ENTRE CULTIVARES DE SORGO(Sorghum bicolor (L.) Moench) ATRAVÉS DE MARCA DORESMOLECULARES RAPD. Maria José Vilaça de Vasconcelos 1 e FredolinoGiacominj dos Santos" 1) CNPMS, Caixa postal 151,35701-970 - Sete Lagoas(MG).Nos programas de melhoramento genético usam-se análises fenotípicas paraevidenciar variabilidade genética entre indivíduos. Nos últimos anos têm-seutilizado marcadores como Isoenzimas, RFLP e Microssatélites para estudar adistância genética entre cultivares de várias espécies vegetais. Neste trabalhopropõe-se o uso de marcadores moleculares do tipo RAPO ("Random AmplifiedPolymorphic DNA") como potente ferramenta na caracterização de linhagens ede potenciais progenitores em programa de melhoramento de Sorgo. Foramselecionados pelo programa de melhoramento de sorgo do CNPMS 20materiais para um estudo inicial. O DNA total de folhas desses materiais foipurificado e amplificado utilizando-se iniciadores de sequência aleatória, ondeas reações de amplificação consistiram de 40 ciclos de desnaturação a 94° Cpor 15 seg, pareamento a 35° C por 30 seg e alongamento a 72° C por 1min euma etapa de 7 min a 72° C para o alongamento final. Todos os iniciadoresutilizados geraram pelo menos uma banda polimórfica. Os dados obtidos foramutilizados para a determinação da distância genética entre os genótipos, suaseparação em grupos (Uclusters") e em análise multivariada. <,Apoio Financeiro: EMBRAPA155

Estudo da variabilidade genética entre cultivares de sorgo (Sorghum bicolor (L.) Moench) através de marcadores moleculares RAPD.

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