Table of Contents | Genet. Mol. Res. 2019 (4)
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.
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.
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.
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.
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.
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.
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.
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.
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.