Rita Carolina de Melo

Mutation induction as a strategy to overcome the restricted genetic base in Physalis

1Instituto de Melhoramento e Genética Molecular IMEGEM, Universidade do Estado de Santa Catarina UDESC/ Lages-SC. E-mails: nicoletrevisani88@ gmail.com; rita_carol_mel@hotmail.com; joaopedrofossabernardy@gmail.com; coimbrajefferson@gmail.com; altamirguidolin@gmail.com 2Universidade Federal de Santa Catarina UFSC/Curitibanos-SC. E-mail: patgenpierre@gmail.com. Abstract – The restricted genetic base in physalis in Southern Brazil is a challenge that requires genetic breeding for the achievement of fruits with superior agronomic quality. Therefore, genetic changes were induced in physalis for the selection of populations with superior fruit quality. To that end, seven populations of physalis were submitted to gamma irradiation (0,100 and 200 Grays – Gy), which provided 21 populations. Significant population difference was observed, which indicates the existence of variability between at least two populations of physalis. The contrasts showed difference for Colômbia01, Colômbia02, Caçador and CAV. The mutation induction was effective at causing genetic variations in these populations. For Colombia01 (100 Gy), it was observed reduction of 3.97 mm and 2.56 mm (200 Gy) in the transverse fruit diameter (DTF). In the Colombia02 population (200 Gy), there was an increase of 2.99 mm in the longitudinal fruit diameter (DLT) and 4.90 mm in the DTF. For CAV (200 Gy), it was found the increase of 1.81 oBrix. Mutation induction was beneficial in these cases, but fruit quality is still below the potential of the crop, when compared to fruits from Andean countries. It is possible to suggest that quantitative traits, such as fruit mass (MF) and total soluble solids (SST), and the degree of ploidy in physalis (2n = 4x = 48) reduce the mutagenic agent ability to cause variations.

Ploidy and DNA content of cape gooseberry populations grown in southern Brazil

ABSTRACT Studies detected chromosomal variability in genotypes of Physalis peruviana L. cultivated in Andean countries, with the existence of diploid and tetraploid genotypes and other variations. Knowledge about the ploidy level in cape gooseberry genotypes grown in southern Brazil is essential to define efficient breeding strategies, for example, in the knowledge of the effects caused by inbreeding and heterosis in obtaining commercial hybrids. The objective of this study was to determine the chromosome number and quantify nuclear DNA by flow cytometry in cape gooseberry populations grown in southern Brazil and in Andean populations. To this end, four cape gooseberry populations of different origins (from Lages and Caçador in Brazil, and Colombia and Peru) were subjected to classical cytogenetic analysis (chromosome counting) and flow cytometry. The chromosome number of the four populations was found to be 2n = 4x = 48, classifying them as polyploid with tetraploid cells. Uniformity was also detected in the amount of DNA, ranging from 12.87 to 13.98 pg, with low coefficients of variation (1.9 to 4.2%). The Tukey’s test confirmed the uniformity between populations as to the amount of DNA. Therefore, tetraploid cape gooseberry populations cultivated in southern Brazil have a 2C DNA mean of 13.23 pg. The chromosomal uniformity reveals that cultivation in Brazil was initially based on the sampling of a small number of plants purchased from Colombia, which may already have been subjected to selection for polyploidy.

Heterozygosity level and its relationship with genetic variability mechanisms in beans

Heterozygosity is an extremely important resource in early breeding programs using autogamous plants because it is usually associated with the presence of genetic variability. Induced mutation and artificial hybridization can increase distinctly the proportion of loci in heterozygosis. This study aimed to compare segregating and mutant populations and relate the mechanisms used to generate variability with their respective heterozygosity levels tested. The treatments mutant populations (M2, M3, M4, M5, M6 and M7), segregating populations (F4, F5 and F6) and lines (BRS Perola and IPR Uirapuru) were evaluated by multivariate analysis and compared by orthogonal contrasts. The canonical discriminant analysis revealed which response variables contributed to differentiate the treatments assessed. All orthogonal contrasts involving the mutant populations showed significant differences, except the contrast between M2 vs. M3, M4, M5, M6, M7. The orthogonal contrast between the mutant and segregating populations denotes a significant variation in the interest in genetic breeding. The traits stem diameter (1.41) and number of legumes per plant (2.72) showed the highest canonical weight in this contrast. Conversely, number of grains per plant (-3.58) approached the mutant and segregating populations. No significant difference was observed in the linear comparison of means F5 vs. F6. The traits are fixed early in the segregant populations, unlike the mutant populations. Comparatively, induced mutation provides more loci in heterozygosis than artificial hybridization. Selection pressure should vary according to the variability creation mechanism used at the beginning of the breeding program.

ASSOCIATIONS BETWEEN TRAITS IN FISÁLIS: A TOOL FOR INDIRECT SELECTION OF SUPERIOR PLANTS

O conhecimento da associacao entre caracteres e de fundamental importância no melhoramento de plantas, uma vez que a selecao indireta pode acelerar a obtencao de genotipos promissores. Este trabalho teve como objetivo quantificar a magnitude da associacao entre caracteres de importância agronomica na cultura da fisalis. O experimento foi conduzido em Lages-SC, e os tratamentos foram constituidos de seis populacoes de fisalis. O delineamento experimental foi em blocos casualizados, com duas repeticoes e sete plantas por parcela. A correlacao entre os caracteres foi estimada com base nos coeficientes de correlacao de Pearson e particionados em efeitos diretos e indiretos por meio da analise de trilha. Houve associacao positiva entre a massa do fruto e o numero de sementes (0,874), diâmetro equatorial do fruto (0,738) e diâmetro polar do fruto (0,672). Por meio da analise de trilha, foi possivel verificar maior contribuicao direta do carater numero de sementes sobre a massa do fruto. A elevada magnitude de correlacao fenotipica entre diâmetro equatorial do fruto e diâmetro polar do fruto com a massa do fruto deve-se, principalmente, ao efeito indireto via numero de sementes (0,505 e 0,459). A selecao de frutos de fisalis com maior massa e fortemente influenciada pelo numero de sementes, de maneira que este carater deve ser considerado no momento da selecao.

Correlação fenotípica e efeitos diretos e indiretos de componentes da parte aérea com a distribuição radicular de feijão-comum

The objective of this work was to estimate the phenotypic correlation and the direct and indirect effects of the aerial part components of common bean (Phaseolus vulgaris) that are associated with root distribution, in order to facilitate the indirect selection for this character. Sixteen genotypes were used, from which 12 are segregating populations in the F6 generation and four are fixed populations, which were conducted in field conditions in a randomized complete block design, with two replicates. The root system evaluation was performed according to Böhm’s method. Pearson’s phenotypic correlation was estimated by the path analysis. The characters stem diameter, leaf area index, first pod set, and root angle showed the highest positive correlations with root distribution and, therefore, may help the indirect selection for this character. The residual effect was higher than the determination coefficient, which indicates that the independent characteristics do not have a total influence on root distribution, and the low values of the determination coefficients can be attributed to environmental effects, competition for nutrients, and to different physiological mechanisms that control the expression of several genes with minor effects.

Herança predominante de caracteres em trigo com enfoque multivariado

The objective of this study was to analize the inheritance of characters in wheat using multivariate analysis of variance. Sixteen genetic constitutions were evaluated between commercial cultivars and progenies F1 and F2. Treatments were arranged in completely randomized blocks, with three replicates. Five characters were evaluated. Multivariate analysis of variance and multivariate contrasts were then performed to test the hypotheses. The significant differences, obtained for comparison between parents and progenies F1, may be evidence of heterosis occurrence. However, only comparisons between progenies P1_P3 (F1) vs. P1_P3 (F2) and P4_P2 (F1) vs. P4_P2 (F2) showed significant differences. Multivariate analysis of variance revealed that inheritance of the characters studied is predominantly of the additive type. It is possible that, this occurred due to the degree of relationship between parents who reunited identical alleles at the same locus, by ancestry, as a result of inbreeding effects. The knowledge of additive inheritance may represent a faster incorporation of resistance or quality characteristics in new cultivars.