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Table of contents: 2019

Research Article

Cotton has high adaptability to adverse conditions; however, one of the main factors causing production loss is water deficits. To adapt to these conditions, plants go through a series of changes, many of them driven by genes that are expressed to increase drought tolerance. We examined the expression profile of the MYB60 and GUSP1 genes, which are involved in the abiotic stress pathway, focusing on drought tolerance. Four Upland and Mocó genotypes were submitted to water stress during early growth and further evaluated at 50% (phase 1) and 80% (phase 2) of stomata enclosure. Plants were previously phenotyped, based on vegetative, physiological and biochemical traits. Expression of GUSP1 and MYB60 transcripts was estimated by qRT-PCR. Plants were grown in 288 mL pots in a greenhouse and further submitted to water stress during 25 days. Although Mocó cotton is considered tolerant to drought and upland cotton is known to be drought-sensitive; we found a different behavior in these genotypes. Mocó 1 was very sensitive to the imposed water deficiency stress, with severe reductions in leaf number, stem diameter and weight of roots and canopy, while Delta Opal (Upland) presented the smallest reductions in growth. Expression of GUSP1 transcripts was higher in all stressed genotypes, in both phases, during the water stress period, with the genotype Mocó 2, presenting the highest level of expression, while MYB60 transcripts were high expressed only in phase 1, decreasing in phase 2. Considering that differences in the expression of MYB60 can be detected earlier, because the peak of expression occurred at phase 1 of water stress, it is worth investigating the genetic diversity in cotton germplasm to select genotypes with drought tolerance and to estimate the relation with the expression of MYB60, since Mocó genotypes were considered tolerant, but in this work a Mocó 1 genotype presented drought-sensitive characteristics.

Genet. Mol. Res. 18(4): GMR18319
DOI: 10.4238/gmr18319
Research Article

The peanut plant has high plasticity and great adaptability to adverse conditions, including drought. To mitigate the negative effects of drought on legumes, nitrogen-fixing microorganisms have been investigated in some plant species, such as soybeans and beans. We analyzed the role Bradyrhizobium strains in peanut genotypes subjected to water deficit by means of plant growth, physiological and gene expression analysis. The research was conducted under greenhouse conditions with the runner peanut genotypes (IAC Runner 886, 2012-33 and 2012-47) and two Bradyrhizobium strains (ESA 123 and SEMIA 6144). After 20 days of germination, the water supply was completely interrupted and gas exchange analysis were carried out using an infrared gas analyzer, up to the 10th day of stress. Leaves were collected for the analysis of proline content and the expression of NCED and ERF8 genes. Analyses of plant height (PH), shoot dry mass (SDM), root dry mass (RDM), number of nodules (NN) and nodule weight (NW) also were performed. The peanut shoots inoculated with the Bradyrhizobium strains obtained the best results. The genotypes inoculated with the ESA 123 strain obtained superior responses compared to the non-stressed treatment inoculated with the same bacteria and the stressed control without bacterial inoculation. In the ESA 123 inoculated treatments, the water stressed plants had higher RDM (28.5% higher, on average), NN (two fold higher), and gene expression (approximately six and three-fold higher for ERF8 and NCED genes, respectively). The increase in the expression of NCED and ERF8 genes, in the three genotypes inoculated with ESA 123, suggests a key role of this inoculant in the activation of metabolic cascades for plant protection under water deficit.

Genet. Mol. Res. 18(4): GMR18379
DOI: 10.4238/gmr18379
Research Article

Focusing on the genetic traits, seed coat and hilum pigmentation, in soybeans destined for human consumption is necessary due to the relevance of these traits for product acceptability by the consumer market. We investigated the traits seed coat, hilum color and bleeding hilum, in F2:3 populations originating from crosses between the soybean grain type ('BRSMG 810C' with yellow seed coat, black hilum, and gray pubescence; bleeding hilum and white flower) with food types (‘BRSMG 790A’ with yellow seed coat and hilum, brown pubescence, no bleeding hilum and purple flower; 'BRSMG 800A' with brown seed coat and hilum, brown pubescence, no bleeding hilum and purple flower).We evaluated 317 plants from cross A ('BRSMG 810C' x 'BRSMG 790A') and 357 plants from cross B ('BRSMG 810C' x 'BRSMG 800A'). The resulting progenies adjusted to the expected ratio, considering four genes (R/I/W/T) controlling the expression of seed coat and hilum pigmentation for both crosses. In cross B, genotypes ii prevented the expression of the W and T alleles in the seed coat pigmentation. The expression of the bleeding hilum phenotype varied and presented monogenic inheritance, with complete dominance for no bleeding hilum. The genes responsible for bleeding hilum are linked with the T_ genotype (brown pubescence). Thus, in these crosses,hybridization was an efficient means to obtain genetic variability. This will aid in the production of for food grade soybean cultivars.

Genet. Mol. Res. 18(4): GMR18372
DOI: 10.4238/gmr18372
Research Article

Cassava is one of the main energy foods for millions of people, and has a great diversity of ethno-varieties that have specific characteristics often not found in commercial varieties. These constitute a gene pool and therefore a genetic resource that should be conserved and preserved. In this context, the objective of our study was to evaluate the genetic diversity and population structure of ethno-varieties of cassava grown in six municipalities of the state of Mato Grosso, with the aim of characterization and conservation of the varieties found in this area. The study was carried out with 157 samples of cassava. For the molecular analyses, 15 fluorochrome-labeled SSR loci were used. Microsatellite markers amplified a total of 158 alleles. The polymorphism information content for each locus varied from 0.132 (SSRY126) to 0.838 (SSRY47), with a mean of 0.680. The expected and observed heterozygosity showed an average of between 0.717 and 0.688, for SSRY126 and SSRY47, respectively. The heterozygosity values observed were higher than those expected in five of the six populations, generating negative values of the fixation index (-0.070). Among the six populations, Alta Floresta and Cuiabá had the highest percentage of polymorphic loci (100%). The groupings obtained by UPGMA, Structure and PCoA among the six populations were concordant in allocating the individuals into two genetic groups. We found considerable genetic diversity among the samples, evidenced by the high values  in the diversity indices. These high values are possibly related to the management of the fields and the exchange of propagative material among the farmers. Therefore, it is proposed that both populations be conserved since they have potential that could be used for genetic improvement of this essential crop.

Genet. Mol. Res. 18(4): GMR18357
DOI: 10.4238/gmr18357
Research Article

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. phaseoli (Fop) is one of the most important diseases of common bean and occurs in many regions of the world. However, there is little available information that could elucidate when and where the fungus attacks common bean plants. To study the colonization of common bean by this fungus, we transformed Fop Brazilian race 2 for egfp gene expression and used these fungal transformants to analyze the colonization process in common bean roots and stems. The combined use of driselase and lysing enzyme was sufficient for Fop mycelium protoplastization. The PEG-CaCl2 transformation protocol allowed us to obtain stable transformed fungi, with colonies expressing the egfp gene. Regarding colonization by Fop transformants, the fungus grew intercellularly on the root hair epidermis at six days post-inoculation (DPI) and on parenchymal cells at 11 DPI on plants of the susceptible line. At 19 DPI, the fungus reached xylem vessels, blocking water and mineral passage in shoots, resulting in wilt and plant death at 25 DPI. Using fluorescence to mark the fungus revealed details of Fop colonization of common bean tissues.

Genet. Mol. Res. 18(4): GMR18370
DOI: 10.4238/gmr18370
Research Article

We evaluated the efficiency of three mechanical detasseling methods on the production of hybrid maize seeds. The experiment was run in the crop season of 2016/2017 in Indianópolis, MG, Brazil. The design used was random blocks, where the treatments corresponded to three detasseling methods: Puller (PUL) - based on only one mechanical detasseling operation, Cutter 2x + Puller (C1P) - based on two mechanical detasseling operations by the Cutter method and one operation by the Puller method, and Cutter + Puller (C2P) - based on only one operation by the Cutter method and one operation by Puller. There was variability in the effects and efficiency of the mechanical detasseling methods in the production of hybrid maize seeds. The two methods C1P and C2P had small differences; both being superior to PUL. The mechanical detasseling method based on one operation of Cutter and one operation by Puller method is recommended, since it minimizes costs, lowering transfer and genetic contamination as well, and it optimizes the production of hybrid maize seeds per plant and unit area.

Genet. Mol. Res. 18(4): GMR18207
DOI: 10.4238/gmr18207
Research Article

The production of onion hybrids depends on the development of genetically pure lineages. Successive self-fertilization guarantees obtaining endogenous lines quickly. However, onion undergoes a strong process of inbreeding depression when self-fertilized for several generations, which reduces plant vigor, bulb size and seed production, increasing the cost to produce hybrid seed. An estimate of the genetic distance between genotypes is a way of predicting if genetic variability is being maintained. We evaluated possible negative effects in populations due to self-fertilization, compared to interbreeding between two or three plants. Eleven onion populations in different genetic segregation stages, obtained from generations that already had low or moderate inbreeding levels were included. The populations were from the breeding program of Bayer Vegetable Seeds. In order to assess the agronomic descriptors contribution for the genetic divergence, three types of crossing methods of populations were performed: self-fertilization of plants, crossing between two plants and crossings between three plants, during two consecutive years (2014 and 2015). Morphological differences were detected through dissimilarity measures. The traits bulbs/plot (28.32%), fruit fixation (13.12%) and seed weight/umbel (13.41%) together contributed 54.85% to the divergence of onion genotypes. The crosses between two and three plants provided greater divergence among the genotypes, compared to self-fertilization. Economically important traits such as bulb production per plot, fruit fixation, resistance to disease caused by Alternaria porri (Pleosporaceae) and seed weight per umbel can be measured to assess divergence for appropriate selection of onion lineages among segregant populations.

Genet. Mol. Res. 18(4): GMR18256
DOI: 10.4238/gmr18256
Research Article

We evaluated the performance of 25 soybean genotypes sown in the off-season, to identify the morphological attributes and yield determinants for seed yield in this period. The selected genotypes are commonly used among farmers and were purchased from seed traders. Sowing of soybeans during non-preferential times is common in the northern part of the state of Rio Grande do Sul where it is sown after maize as a late crop. The objective was to evaluate the most suitable genotypes for non-preferential cultivation. The experiment was conducted in the agricultural crop year of 2017/2018 in Tenente Portela - RS; the experimental design was a randomized block containing 25 soybean genotypes arranged in three replicates. Analysis of variance showed significance at 5% probability; there was variability for the first pod insertion height, plant height, number of pods on the main stem, number of pods in the branches, number of branches in the main stem, branch length, number of pods containing one seed, number of pods containing two seeds, number of pods containing three seeds, seed mass per fractional plant due to the pod of origin containing one, two and three seeds and seed yield. The genotypes with the highest seed yield in the off-season period in the Northwest of the state of Rio Grande do Sul were BS 2606 IPRO, BMX Magna RR and M 5947 IPRO. The productivity in kg per hectare was established with taller plants with superiority in the number of pods on the main stem, these pods being formed by two to three viable seeds.

Genet. Mol. Res. 18(4): GMR18230
DOI: 10.4238/gmr18230
Research Article

We evaluated the effects on the nutritional value of the forage of five genotypes of wheat with dual purpose submitted to different sowing densities, as well as different cutting managements. The experiments were carried out in the agricultural crop years of 2013 and 2014 in Frederico Westphalen, RS. The experimental design was a randomized block, organized in a factorial scheme with five genotypes of dual purpose wheat (BRS Tarumã, BRS Umbu, BRS Figueira, BRS Guatambu and BRS 277) x five sowing densities (75, 150, 225, 300 and 375 seeds per square meter) x three cutting managements (one, two and three cuttings), arranged in three replicates. The attributes of interest were obtained through the collection of all plants per experimental unit. These included percentage of crude protein, lipids, neutral detergent fiber and non-fibrous carbohydrates. The bromatological quality of forage from wheat with dual purpose depends on cutting management, genotype and sowing density. The maximum protein fraction and non-fibrous carbohydrates in the forage was obtained at intermediate sowing densities of 300 and 375 seeds per square meter, independent of the genotype for the largest number of cuts.

 

Genet. Mol. Res. 18(4): GMR18211
DOI: 10.4238/gmr18211
Research Article

Passion fruit is a native fruit of tropical America, with Brazil being the world's leading producer and consumer of this fruit, with an estimated annual production of 554,598 Mg, and yield of 13,500 kg.ha-1 Phenotyping through digital images has been used to evaluate morphological characteristics of seeds. Knowledge of the degree of genetic divergence plays an important role, as it assists in the adoption of appropriate strategies for improvement in passion fruit populations. . The objective of this work was to estimate the genetic divergence among full-sibling families of passion fruit through morphophysiological characteristics of seeds using the Ward-Modified Location Model (Ward-MLM) method. Seeds of 98 full-sibling families (FSF) of passion fruit from the breeding program of the Mato Grosso State University were evaluated considering physiological descriptors of seeds, using germination and vigor tests; and morphological descriptors of seeds, using a digital imaging seed analysis device and software. We found that the Ward-MLM method was efficient in detecting genetic divergence using seed morphological and physiological descriptors, simultaneously. The descriptors that contributed the most to the genetic divergence among FSF were those related to seed geometry. This method formed three heterotic groups. Group II had the largest mean emergence speed index (1.106) and seedling emergence percentage (65.8%), and Group III had the largest means of seedling dry weight (4.140 g), radicle length (6.30 mm), germination speed index (2.503), and seed germination percentage (90 %). We conclude that crosses between FSF groups II and III are a good option to improve seed characteristics.

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Genet. Mol. Res. 18(3): GMR18331
DOI: 10.4238/gmr18331
Research Article

The aim of this study was to perform a genome wide association study for the coefficient of adaptability, the heat tolerance coefficient, age at first calving and calving interval, using 58,868 and 57,482 single nucleotide polymorphisms obtained from 1262 Blanco Orejinegro and 742 Sanmartinero individuals, implementing a single-step-genomic-BLUP (ssGBLUP) methodology. A total of 25 and 11 genomic regions in BON and SM were associated with the traits evaluated. In these regions; several genes involved in the regulation of reproduction and adaptability were identified. Some of them, such as the RPTOR, TM2D1, RAB21 and ACOT13 genes, are involved in the physiological response to heat stress. SLC6A16, TMEM50A, NLRP9, KHDRBS2 and UBE2C are possibly associated to reproductive performance. The results of this study indicate an association between some genomic regions and reproductive and adaptability-related traits in Colombian cattle breeds. Several genes contained in these regions can potentially be used in animal breeding programs to select for adabtability within cattle production systems located in a tropical environment.

 

Genet. Mol. Res. 18(3): GMR18373
DOI: 10.4238/gmr18373
Research Article

Bassia indica is a natural herb of medical and economic importance with a worldwide distribution, including in various regions of Egypt. It is primarily used for healing and is also considered a green fodder and can be used to remediate salty soils. We investigated morphological and germination parameters as well as the karyotype and genetic variation of B. indica by DNA-RAPD. Three samples of this species were collected from various localities in Egypt¸ namely the Northern Coast, the Delta region and Upper Egypt, which each represent different ecosystems. The morphological analysis, which included several traits, showed no significant difference between the localities. However, germination varied among the different populations from the different localities. The chromosomes of this species were found to be diploid, being 2n=18 at all localities. Genetic distances based on DNA-RAPD ranged from 0.13 to 0.31 in the samples from the different localities. A dendrogram based on these distances showed close similarity between the B. indica populations collected from the Delta region and Upper Egypt, indicating that they are closely related to each other, while both these populations are quite distant from those from the Northern Coast. This study provides useful information for the classification, chromosomal identification, and germination of B. indica in these regions that have distinct soils and climate.

Genet. Mol. Res. 18(3): GMR18417
DOI: 10.4238/gmr18417
Research Article

An option into guide selection strategies in soybean breeding programs is to investigate associations between the main traits studied by breeders. A question that is faced is the possible influence of genotype x environment (GE) interactions on correlations among traits. Path analysis allows, in addition to measuring correlation, a more detailed study of cause / effect relationships among traits. We measured the effect of the GE interaction in the association between agronomic traits in soybeans. The experiments were carried out during two crop seasons, in three municipalities of Minas Gerais, Brazil, using a randomized complete blocks design, with 35 treatments. We evaluated number of grains, number of pods (NP), number of grains per pod, grain yield, weight of 100 grains, lodging score, plant height, height of first pod insertion, and full maturity. The data were submitted to variance analysis and path analysis. We also calculated the sum of ranks index in three ways, considering different economic weights. The correlation between grain yield and other traits, as well as direct and indirect effects, varied in magnitude and direction, considering individual and multi-environmental analyses, demonstrating the influence of the GE interaction. For example, considering the individual analysis for Lavras in 2015/16, the correlation between grain yield and NP was -0.0534 and was not significant at the 5% level by the Mantel test, and the direct effect of NP on grain yield was 0.1717, while in the joint analysis of all environments, the correlation between these traits was 0.3674 and was significant, and the direct effect of NP on grain yield was -0.0520.The direct effect as an economic weight in the sum of rank index can be more efficient in selecting cultivars when compared to a simple correlation; this could become a useful strategy for the selection of multiple traits.

Genet. Mol. Res. 18(3): GMR18099
DOI: 10.4238/gmr18099
Research Article

Soybean rust is considered a highly aggressive disease in soybean crops. Most research has focused on obtaining resistant genotypes based on dominant or recessive alleles, which provide vertical resistance. The identification of promising crosses that may be used to develop genotypes with horizontal resistance from IAC 100 may help to increase the longevity of the recommended cultivars. However, this type of resistance is limited by environmental variables that may hinder selection. We ranked crosses based on their response to soybean rust using genetic estimates and predicted gains. It was also an objective to identify quantitative trait loci (QTLs) associated with resistance to soybean rust in two generations derived from the same cross. Eighty-seven F4 progenies from IAC 100 (partial resistance) x BRS Caiapônia (susceptible) cross were field phenotyped. The data divided the DNA samples into two groups for bulked segregant analysis, which was carried out using simple sequence repeat (SSR) primers. A linkage map for the F4 generation was obtained based on 29 SSR markers, which were distributed into nine linkage groups, covering 285.9 cM of the genome. Six QTLs were mapped in four of these groups and two of them were responsible for 39% of the phenotypic variance in resistance to soybean rust. The linkage map generated for the F7 generation was similar to that of the F4 generation, covering 266 cM. Four of the six QTLs mapped in the F4 generation were also identified in the F7 generation, showing that the genomic regions contributing to horizontal resistance to soybean rust are stable.

 

Genet. Mol. Res. 18(3): GMR18249
DOI: 10.4238/gmr18249
Research Article

Dual purpose wheat could be a good alternative for helping overcome the need to import this cereal in Brazil. To achieve this, development of cultivars with high yield is necessary. The contribution of genetics in defining traits is very important for directing breeding programs for the development of cultivars that provide the desired agronomic ideotype. We estimated heritability for 36 characters of agronomic importance in dual-purpose wheat. The inheritable genetic patterns were examined using linear trends, a Euclidean algorithm, factor analysis and artificial neural networks. The study was carried out during the crop seasons of 2011, 2012 and 2013. The experimental design was randomized block, arranged in a factorial scheme with three growing seasons (2011, 2012 and 2013) and five dual-purpose wheat genotypes (BRS Tarumã, BRS Umbu, BRS Figueira, BRS Guatambu and BRS 277) x three cuttings (first cutting, second cutting and third cutting), with three replicates. Deviance analysis or maximum likelihood was significant for the 36 characters. The length of the head of the main plant, plant height before the first second cutting and dry mass of the seedlings showed high variability. The 36 characters expressed linear genetic dependence based on the Euclidean Algorithm; similar to what was found with the Tocher Optimized Clustering and Artificial Neural Networks K-means methods. Similar genetic trends for heritability profiles were obtained with factor analysis and Artificial Neural Networks by the Kohonem method. The use of Artificial Neural Networks through the Kohonem method gave the greatest efficacy in the definition of the genetic profiles needed to develop the recommended agronomic ideotype for the improvement of dual-purpose wheat.

 

Genet. Mol. Res. 18(3): GMR18266
DOI: 10.4238/gmr18266

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