Search

The objective of this study was to develop segregating wheat populations for resistance to gibberella through the introgression of synthetic wheat genes in traditional cultivars and to present the results using the backcross method. In addition, to evaluate these populations in F1RC2, agronomic aspects and type II and III resistance to Fusarium head blight (FHB). The cultivars BRS Guamirim and BRS 179 were used as male parents and three synthetic wheat cultivars (CIGM90.909, CIGM92.1666, and CIGM93.298) as female parents, both previously characterized for the reaction to FHB. Crossing and backcrossing methodological procedures were performed to provide adequate controlled conditions. The F1 (winter 2016), RC1 (summer 2016/2017), and RC2 (winter 2017) populations were developed through emasculation and pollination procedures. In the winter of 2018, segregating populations were evaluated in the field using a randomized block design. In the three generations developed in a greenhouse, it was observed that the best crossbreeding combinations, verified by the number of grains, were obtained with the male parent BRS 179. Under field conditions, all segregating populations were considered moderately susceptible and susceptible to type II resistance. In type III resistance, all segregating populations, except for CIGM90.909/BRS 179 and BRS 179, showed values above 50%. Thus, it was evident that the crossings performed with the male parent BRS 179 generated better resistance to the disease.

The objective of this study was to evaluate genetic stability by determining the meiotic index (MI) and pollen viability in F1RC2 segregating populations, obtained by the crosses between wheat commercial cultivars and synthetic wheat, aimed at introgression/genetic resistance. For MI, three ears were collected per genotype, before anthesis, and they were fixed in Carnoy’s solution. The cytological slides were prepared by crushing the anthers and staining with 1% acetocarmine, and the normal tetrads and the ones with micronuclei were observed under a light microscope. For pollen viability, the ears were collected at the stage of mature pollen grain. The methodological procedure was similar to that of the tetrads, evaluating the pollen grains as viable, with little starch, with two pores, different sizes and non-viable. The pollen grain size was measured by the Axion Vision software. All the segregating populations with MI above 90% and high pollen viability (above 85%) reflected a stable meiotic behavior. About the variation in size, the CIGM90.909/BRS 179 cross showed pollen grains with 58.43 μm and CIGM93.298/BRS Guamirim, 47.15 μm. According to the results, wheat segregating populations were considered meiotically stable and suitable for use in wheat breeding programs and for incorporation of new important genes.

Abstract: The objective of this work was to assess the androgenic response, via microspore culture, of wheat genotypes with different levels of resistance to Gibberella zeae. The number of androgenic embryos per spike, and of green and albino plants was counted for the BRS 179 (moderately resistant), Frontana and Sumai 3 (resistant), and BRS 194, Embrapa 27, and Fielder (susceptible) genotypes. The degree of interference by the Fielder, Pavon 76, and Sumai 3 ovary-donor genotypes, used for co-culture with the microspore cells, was also assessed regarding androgenic response. Induction efficiency ranged from 0.33 embryo per spike for Embrapa 27 to 109.8 embryos for Frontana. Sumai 3 presented the second best response, and Embrapa 27 behaved as highly recalcitrant. The co-culture of ovaries from the Fielder genotype stands out from the others and positively interferes in the embryo induction rate. No significant differences were observed for the regeneration frequency of green plants; however, for albino plants, BRS 194 produced the highest rate. Frontana and Sumai 3 present the highest androgenic response rates and can be used in breeding programs for the rapid development of cultivars resistant to Gibberella zeae.

The wheat cultivar ‘BRS 331’ was developed by Embrapa. It results from an interspecific cross between wheat and maize by double-hapolid method. ‘BRS 331’ shows solid stem in the base of the plant, short leaves and super-early cycle to maturity. It is classified as bread wheat in all of the regions that is recommended in the States of Rio Grande do Sul, Paraná and Santa Catarina, Brazil.

A cultivar de trigo 'BRS Marcante' foi desenvolvida pela Embrapa, envolvendo um híbrido F1 do cruzamento entre as linhagens PF 980533 e PF 970227 com a cultivar 'BRS Guamirim', realizado em telado, na Embrapa Trigo, no inverno de 2003. As gerações segregantes foram conduzidas pelo método genealógico e a linhagem resultante, nomeada de PF 080310. A cultivar caracteriza-se pela sua ampla capacidade de adaptação às condições de cultivo do sul do Brasil, pelo bom potencial de rendimento de grãos e qualidade industrial da classe Pão

The triticale cultivar BRS Minotauro was developed by the Brazilian Agricultural Research CorporationEmbrapa. It is a result of a cross of Brazilian wheat and rye with hexaploid triticale. BRS Minotauro is hexaploid, has amedium cycle, medium to tall plant stature, adapts extremely well to cultivation conditions in the south of Brazil, with anaverage grain yield of 3,790 kg ha-1, i.e., 9% higher than the mean yield of the controls, and has a high yield stability indifferent environments.

ABSTRACT: Synthetic wheat is developed by crossing tetraploid species ( Triticum turgidum , AABB) with a diploid species ( Aegilops tauschii , DD), followed by chromosome duplication through the use of colchicine to restore the resultant sterile hybrid to a fertile hexaploid plant. The main importance of producing synthetically improved wheat is to increase their genetic variability and to incorporate genes that code for resistance to biotic and abiotic stressors. This study aimed to evaluate the presence of micronuclei (MN) and the meiotic index (MI) in the tetrad phase in synthetic wheat accessions and cultivars ( Triticum aestivum ) stored at the Germplasm Bank of Embrapa Trigo (Brazil), in order to identify and select genetically stable accessions for plant improvement. Five plants were collected by genotype, prior to anthesis, and the tissues were fixed in Carnoy solution. Cytological slides were prepared by the smash method, and the cells were dyed with 1% acetocarmine and observed under an optical microscope. Presence of MN was observed in all genotypes analyzed, and variability of genetic stability was reported in the two years of analysis. In 2014, the highest MI of synthetic wheat accessions was 96.86% and the lowest was 46.32%. In 2015, the highest MI was 96.60% and the lowest was 47.96%. Based on the results, some genotypes were considered meiotically stable and suitable for use in wheat breeding programs.