Genetic structure analysis of Mauritia flexuosa natural population from the Lençóis Maranhenses region using microsatellite markers

Buriti (Mauritia flexuosa L.f), a palm tree native to South America and widely distributed in Brazil, displays significant ecological, economic and biotechnological importance. However, the disorderly extractivism and environmental degradation of its endemic areas are leading to reductions in, and/or extinction of the buriti palm tree, causing ecological imbalance with significant economic losses for rural communities and genetic diversity. Consequently, populational genetic diversity studies have become relevant as a strategy for conserving the species. Therefore, this study evaluated the genetic structure of 10 populations from the Lençóis Maranhenses region, in the state of Maranhão, Brazil, using microsatellite markers. Results indicated that eight pairs displayed a high level of polymorphism in the populations evaluated (98.5 %). The genetic diversity estimations allowed for identifying 220 alleles (average of 9.5 alleles/loci), and the heterozygosity averages observed (Ho) were lower than the heterozygosity expected (He) in the population (0.16 and 0.64) and loci levels (0.15 and 0.65), respectively. The Shannon Index (I) mean value of 1.36 indicated high diversity and genotypic richness in the populations evaluated, while the population index (FST) indicated a low value (0.05) and the fixation index pertaining to individuals indicated a high value (FIS = 0.79) exhibiting a moderate population distribution structure, and pointing to greater diversity between individuals. Based on these results, populations denominated as PA and PB presented a high genetic similarity (0.219), while populations denominated as PF and PJ exhibited more distant genetic characteristics (0.519). These results can be correlated based on prioritization of conservation of this non–domesticated species, influenced by environmental characteristics, suggesting that the genetic diversity found should be conserved in a germplasm bank, and subsequently exploited in breeding programs.

Genetic structure analysis of Mauritia flexuosa natural population from the Lençóis Maranhenses region using microsatellite markers

Buriti (Mauritia flexuosa L.f), a palm tree native to South America and widely distributed in Brazil, displays significant ecological, economic and biotechnological importance. However, the disorderly extractivism and environmental degradation of its endemic areas are leading to reductions in, and/or extinction of the buriti palm tree, causing ecological imbalance with significant economic losses for rural communities and genetic diversity. Consequently, populational genetic diversity studies have become relevant as a strategy for conserving the species. Therefore, this study evaluated the genetic structure of 10 populations from the Lençóis Maranhenses region, in the state of Maranhão, Brazil, using microsatellite markers. Results indicated that eight pairs displayed a high level of polymorphism in the populations evaluated (98.5 %). The genetic diversity estimations allowed for identifying 220 alleles (average of 9.5 alleles/loci), and the heterozygosity averages observed (Ho) were lower than the heterozygosity expected (He) in the population (0.16 and 0.64) and loci levels (0.15 and 0.65), respectively. The Shannon Index (I) mean value of 1.36 indicated high diversity and genotypic richness in the populations evaluated, while the population index (FST) indicated a low value (0.05) and the fixation index pertaining to individuals indicated a high value (FIS = 0.79) exhibiting a moderate population distribution structure, and pointing to greater diversity between individuals. Based on these results, populations denominated as PA and PB presented a high genetic similarity (0.219), while populations denominated as PF and PJ exhibited more distant genetic characteristics (0.519). These results can be correlated based on prioritization of conservation of this non­domesticated species, influenced by environmental characteristics, suggesting that the genetic diversity found should be conserved in a germplasm bank, and subsequently exploited in breeding programs.(AU)

Genetic structure analysis of Mauritia flexuosa natural population from the Lençóis Maranhenses region using microsatellite markers

ABSTRACT Buriti (Mauritia flexuosa L.f), a palm tree native to South America and widely distributed in Brazil, displays significant ecological, economic and biotechnological importance. However, the disorderly extractivism and environmental degradation of its endemic areas are leading to reductions in, and/or extinction of the buriti palm tree, causing ecological imbalance with significant economic losses for rural communities and genetic diversity. Consequently, populational genetic diversity studies have become relevant as a strategy for conserving the species. Therefore, this study evaluated the genetic structure of 10 populations from the Lençóis Maranhenses region, in the state of Maranhão, Brazil, using microsatellite markers. Results indicated that eight pairs displayed a high level of polymorphism in the populations evaluated (98.5 %). The genetic diversity estimations allowed for identifying 220 alleles (average of 9.5 alleles/loci), and the heterozygosity averages observed (Ho) were lower than the heterozygosity expected (He) in the population (0.16 and 0.64) and loci levels (0.15 and 0.65), respectively. The Shannon Index (I) mean value of 1.36 indicated high diversity and genotypic richness in the populations evaluated, while the population index (FST) indicated a low value (0.05) and the fixation index pertaining to individuals indicated a high value (FIS = 0.79) exhibiting a moderate population distribution structure, and pointing to greater diversity between individuals. Based on these results, populations denominated as PA and PB presented a high genetic similarity (0.219), while populations denominated as PF and PJ exhibited more distant genetic characteristics (0.519). These results can be correlated based on prioritization of conservation of this nondomesticated species, influenced by environmental characteristics, suggesting that the genetic diversity found should be conserved in a germplasm bank, and subsequently exploited in breeding programs.

Combining ability of recombined F4 papaya lines: a strategy to select hybrid combination

The growing demand for quality of papaya by the domestic and international markets requires the development of genotypes that are capable of incorporating traits, such as high yield and fruit quality. This study estimated the genetic parameters and the specific combining ability of F4 papaya lines crossed to the SS-72/12 tester to identify genotypes with higher genetic value for hybrid production. We evaluated 169 treatments consisting of 62 topcross hybrid combinations, 97 F5 lines, and 10 controls in a 13 × 13 lattice design with five replicates and two plants per plot. The following traits were evaluated: plant height (PH), stem diameter (SD), first-fruit insertion height (FFIH), number of marketable fruits (NMF), number of deformed fruits (NDF), number of fruitless nodes (NFN), average fruit weight (FW), and yield (YLD). Differences p < 0.05 were found in most traits evaluated. The specific combining ability estimates indicate that hybrids formed by the cross between SS-72/12 tester and the following lines are promising, considering the multiple traits: UCLA08-088, UCLA08-101, UCLA08-071, UCLA08-014, UCLA08-025, UCLA08-028, UCLA08-122, UCLA08-055, UCLA08-026, and UCLA08-092. These hybrids meet the demands for domestic and international markets and may be available to producers as new papaya cultivars.

Combining ability of recombined F4 papaya lines: a strategy to select hybrid combination

The growing demand for quality of papaya by the domestic and international markets requires the development of genotypes that are capable of incorporating traits, such as high yield and fruit quality. This study estimated the genetic parameters and the specific combining ability of F4 papaya lines crossed to the SS-72/12 tester to identify genotypes with higher genetic value for hybrid production. We evaluated 169 treatments consisting of 62 topcross hybrid combinations, 97 F5 lines, and 10 controls in a 13 × 13 lattice design with five replicates and two plants per plot. The following traits were evaluated: plant height (PH), stem diameter (SD), first-fruit insertion height (FFIH), number of marketable fruits (NMF), number of deformed fruits (NDF), number of fruitless nodes (NFN), average fruit weight (FW), and yield (YLD). Differences p < 0.05 were found in most traits evaluated. The specific combining ability estimates indicate that hybrids formed by the cross between SS-72/12 tester and the following lines are promising, considering the multiple traits: UCLA08-088, UCLA08-101, UCLA08-071, UCLA08-014, UCLA08-025, UCLA08-028, UCLA08-122, UCLA08-055, UCLA08-026, and UCLA08-092. These hybrids meet the demands for domestic and international markets and may be available to producers as new papaya cultivars.(AU)

Papaya recombinant inbred lines selection by image-based phenotyping

The selection of superior Carica papaya (L) genotypes depends on the availability of genetic variability and on the favorable and simultaneous response of the genotypes to those traits of most interest. However, manual phenotyping (MP) demands intensive labor, is time-consuming and expensive. The aim of the current study is to access the efficiency of image-based phenotyping (IBP) in estimating genetic parameters and in selecting F4 recombinant inbred lines. The genetic parameters and values were estimated in accordance with the REML/BLUB procedure and combined selection using the selection index based on standardized genetic values. The majority of traits accessed through IBP showed experimental coefficients of variation similar to those found through MP. Both methodologies showed genetic parameters of similar magnitude, indicating expressive genetic variability between lines in the traits accessed in this study. The same superior lines were indicated in both methodologies and expressive genetic gains obtained through the lines were selected for all traits. IBP performance was similar to that of MP with respect to the estimates of breeding-relevant traits such as commercial fruits and yield. Thus, IBP showed efficient phenotypic assessment, as well as selective accuracy in accessing genetic variability and genetic gains, when it was compared to MP. Since IBP is far less dependent on labor, it is expected to be incorporated into the routine of papaya breeding programs as a way of increasing the number of accessed lines and, consequently, increasing genetic gains.

Papaya recombinant inbred lines selection by image-based phenotyping

The selection of superior Carica papaya (L) genotypes depends on the availability of genetic variability and on the favorable and simultaneous response of the genotypes to those traits of most interest. However, manual phenotyping (MP) demands intensive labor, is time-consuming and expensive. The aim of the current study is to access the efficiency of image-based phenotyping (IBP) in estimating genetic parameters and in selecting F4 recombinant inbred lines. The genetic parameters and values were estimated in accordance with the REML/BLUB procedure and combined selection using the selection index based on standardized genetic values. The majority of traits accessed through IBP showed experimental coefficients of variation similar to those found through MP. Both methodologies showed genetic parameters of similar magnitude, indicating expressive genetic variability between lines in the traits accessed in this study. The same superior lines were indicated in both methodologies and expressive genetic gains obtained through the lines were selected for all traits. IBP performance was similar to that of MP with respect to the estimates of breeding-relevant traits such as commercial fruits and yield. Thus, IBP showed efficient phenotypic assessment, as well as selective accuracy in accessing genetic variability and genetic gains, when it was compared to MP. Since IBP is far less dependent on labor, it is expected to be incorporated into the routine of papaya breeding programs as a way of increasing the number of accessed lines and, consequently, increasing genetic gains.(AU)

Model-assisted phenotyping by digital images in papaya breeding program

Manual phenotyping for papaya Carica papaya (L) breeding purposes limits the evaluation of a great number of plants and hampers selection of superior genotypes. This study aimed to validate two methodologies for the phenotyping of morpho-agronomic plant traits using image analysis and fruit traits through image processing. In plants of the THB variety and UENF/Caliman-01 hybrid two images (A and B) were analyzed to estimate commercial and irregularly shaped fruits. Image A was also used in the estimation of plant height, stem diameter and the first fruit insertion height. In THB fruits, largest and smallest diameters, length, and volume were estimated by using a caliper and image processing (IP). Volume was obtained by water column displacement (WCD) and by the expression of ellipsoid approximation (EA). Correlations above 0.85 between manual and image measurements were obtained for all traits. The averages of the morpho-agronomic traits, estimated by using images, were similar when compared to the averages measured manually. In addition, the errors of the proposed methodologies were low compared to manual phenotyping. Bland-Altman's approach indicated agreement between the volume estimated by WCD and EA using caliper and IP. The strong association obtained between volume and fruit weight suggests the use of regression to estimate this trait. Thus, the expectation is that image-based phenotyping can be used to expand the experiments, thereby maintaining accuracy and providing greater genetic gains in the selection of superior genotypes.

Model-assisted phenotyping by digital images in papaya breeding program

Manual phenotyping for papaya Carica papaya (L) breeding purposes limits the evaluation of a great number of plants and hampers selection of superior genotypes. This study aimed to validate two methodologies for the phenotyping of morpho-agronomic plant traits using image analysis and fruit traits through image processing. In plants of the THB variety and UENF/Caliman-01 hybrid two images (A and B) were analyzed to estimate commercial and irregularly shaped fruits. Image A was also used in the estimation of plant height, stem diameter and the first fruit insertion height. In THB fruits, largest and smallest diameters, length, and volume were estimated by using a caliper and image processing (IP). Volume was obtained by water column displacement (WCD) and by the expression of ellipsoid approximation (EA). Correlations above 0.85 between manual and image measurements were obtained for all traits. The averages of the morpho-agronomic traits, estimated by using images, were similar when compared to the averages measured manually. In addition, the errors of the proposed methodologies were low compared to manual phenotyping. Bland-Altman's approach indicated agreement between the volume estimated by WCD and EA using caliper and IP. The strong association obtained between volume and fruit weight suggests the use of regression to estimate this trait. Thus, the expectation is that image-based phenotyping can be used to expand the experiments, thereby maintaining accuracy and providing greater genetic gains in the selection of superior genotypes.(AU)