Mapeamento e detecção de QTL em mandioca

Abstract

Cassava is typical of the tropics and food security of supply for over 600 million people, used in food human and animal, and industry by extracting of starch and biofuel production. Brazil is the second country in production, but the increase in production is low to meet the growing market. The comprehension of the genetic architecture of agronomically important traits is useful to delineate crossings and enables the identification of quantitative trait loci (QTL) in assisted selection purpose and cloning of candidate genes. This work objective to identify, map and characterize QTL for plant height (AP), shoot productivity (PPA), total yield of fresh roots (PTR), dry matter content of the root (MS) and starch productivity (PROD-AMD) in cassava. For this it was used a F1 population of 141 individuals from the cross between the cultivars Fécula Branca and BRS Formosa kept in randomized block design with two replications and 16 plants per plot for phenotypic analysis. The genotyping of individuals was performed using SNP, microsatellite and minisatellite. The map was constructed multipoint approach and detection of QTL analysis performed for contrast medium and interval of considering the different types of QTL segregation. Variability was observed for all the traits and high correlations, except for MS, especially PTR and PROD-AMD (0.98) and high heritability for AP (74.29%). Also, transgressive segregation was detected for all traits, indicating complementation of parental alleles in segregating progeny. The genetic map represented regions of the 18 chromosomes of cassava and was composed of 283 markers in 32 linkage groups. A region of chromosome 10 showed evidence of pleiotropy. For AP, PPA and AMD-PROD a common QTL was identified as well as PTR, AMD-PROD and three common QTL were checked. MS showed exclusive QTL. These results indicate the quantitative control of the traits studied, with large and small detected QTL effect. These are useful in improving the culture seeking greater productivity.