Inheritance of resistance to Colletotrichum gossypii var. cephalosporioides in cotton

The objective of this study was to analyze the inheritance of the resistance to cotton ramulosis. For thispurpose, two groups of lines with contrasting performance for the evaluated trait were crossed. The disease-susceptibleparents were Delta Opal, CNPA 999 and CNPA 2161, and those with resistance BRS Facual, CNPA 2043 and CNPA 2984,resulting in nine crosses, always of one resistant and one susceptible parent, totalizing 42 treatments. The experiment was setup in a randomized complete block design with three replications. It was verified that the genetic control of ramulosisresistance is predominantly oligogenic, and the number of genes involved depends on the parents that participate in eachcross, due to the possibility of differential loci fixation. Evidence of partial dominance in the sense of increasing diseaseresistance was found, but there were also indications that dominance is not unidirectional

Genetic structure and gene flow of Eugenia dysenterica natural populations Estrutura genética e fluxo gênico em populações naturais de cagaita

This study was carried out to assess the genetic variability of ten "cagaita" tree (Eugenia dysenterica) populations in Southeastern Goiás. Fifty-four randomly amplified polymorphic DNA (RAPD) loci were used to characterize the population genetic variability, using the analysis of molecular variance (AMOVA). A phiST value of 0.2703 was obtained, showing that 27.03% and 72.97% of the genetic variability is present among and within populations, respectively. The Pearson correlation coefficient (r) among the genetic distances matrix (1 - Jaccard similarity index) and the geographic distances were estimated, and a strong positive correlation was detected. Results suggest that these populations are differentiating through a stochastic process, with restricted and geographic distribution dependent gene flow.<br>Este trabalho teve por objetivo o estudo da variabilidade genética em 10 populações de cagaiteiras (Eugenia dysenterica), da região Sudeste do Estado de Goiás. Foram identificados 54 locos marcadores RAPD, para a caracterização da variabilidade genética, avaliada por meio da análise da variância molecular (AMOVA). Foi verificado que 27,03% da variabilidade genética está entre populações, e 72,97% dentro de populações, índices obtidos a partir do valor de fiST igual a 0,2703. Foi estimado o coeficiente de correlação de Pearson (r) entre a matriz de distâncias genéticas (1 - índice de similaridade de Jaccard) e de distâncias geográficas, tendo sido encontrada forte correlação positiva. Os resultados sugerem que essas populações estão se diferenciando por um processo estocástico havendo fluxo restrito dependente da distribuição geográfica