Consequenses of undesirable selfings in the hybrid corn seed production

O presente trabalho foi realizado com o objetivo de avaliar a qualidade fisiológica e componentes da produção, de lotes de sementes híbridas apresentando misturas com sementes provenientes do parental fêmea autofecundado em diferentes taxas. Estudaram-se metodologias para avaliação da pureza genética com o objetivo de identificar sementes provenientes de autofecundação no processo de produção de milho híbrido. Para este estudo, foram produzidas sementes dos híbridos C 901, C 808 A, C 425 e C 701, sendo o primeiro um híbrido simples, o segundo triplo e os dois últimos duplos, e sementes provenientes dos parentais fêmeas autofecundados. Após obtenção dos materiais, sementes provenientes dos parentais fêmeas autofecundados foram misturadas com sementes híbridas nas taxas de O, 5, 10, 20 e 100% e avaliadas em sua qualidade fisiológica, no Laboratório de Análise de Sementes da Escola Superior de Agricultura Luiz de Queiroz, da Universidade de São Paulo. Para avaliação dos parâmetros, estande inicial e final, alturas de planta e de espiga, porcentagem de plantas quebradas e acamadas e produção de grãos, foram conduzidos experimentos em Ituverava, Guaíra, Piracicaba e Paranapanema; nos dois primeiros, a semeadura foi realizada na segunda época de cultivo denominada safrinha e nos dois últimos a semeadura deu-se em época normal. A avaliação da pureza genética foi realizada em sementes, plântulas, plantas com 5-7 folhas, no florescimento, na colheita e em pós- colheita, baseando-se principalmente, em características morfológicas. A análise dos dados e a interpretação dos resultados permitiram concluir que: a) Lotes de sementes de milho do híbrido simples, apresentando mistura com sementes provenientes do parental fêmea autofecundado, apresentam redução na qualidade fisiológica; b) Considerando os quatro híbridos estudados, houve redução média de 0,5% na produção de grãos para cada 1% de sementes provenientes de autofecundação misturadas nas sementes híbridas; c) A redução no rendimento de grãos dos híbridos estudados, decorrente de misturas com sementes dos parentais fêmeas autofecundados, depende, sobretudo, do rendimento das plantas provenientes de autofecundação e da capacidade de compensação das plantas híbridas; d) Em alguns híbridos, é possível separar, com precisão, através de características morfológicas, as plantas autofecundadas das plantas híbridas. A época mais adequada para avaliação da pureza genética varia entre os híbridos.The objective of the present work was to evaluate the physiologic quality and main yield components of hybrid seed lots presenting mixes with seed obtained from female parents with different degrees of selfing. It was also studied the methodologies to evaluate the genetic purity, with the objective of identifying the contaminant selfed seed provoked by bad detasseling of the female parent, in the hybrid seed production process. For this study it was produced hybrid seed and female parent selfed seed of the single cross hybrid C 901, the three way hybrid C 808 A and the double cross hybrids C 425 and C 701. Different ammounts of selfed seed of the parental females were mixed with the correspondent hybrid seed, to obtain samples with O, 5, 1 O, 20 and 100% of selfed seed. These seed samples were evaluated for physiological quality in the seed lab of the Escola Superior de Agricultura Luiz de Queiroz, from Universidade de São Paulo. ln the evaluation of the yield components the traits evaluated were: the initial and final stand, the plant and ear height, the percentage of root and stalk lodged plants and yield obtained by grain weight. The field triais were installed in the safrinha planting season at Ituverava and Guaíra, and the normal planting season at Piracicaba and Paranapanema. The evaluation of genetic purity was made at stage of seedlings, at young plants (5-7 leave plants ), at flowe:ring, at harvesting and, in the ears, after harvesting. The main criteria for evaluation was observation of severa! morphologic characteristics. The analysis of data and interpretation of the results aUowed: a) Com single cross hybrid lots presenting mixes of female parent selfed seed showed reduction in physiological quality; b) The grain yield in the average hybrids studied presented a reduction of 0,5% for each 1,0% female parent selfed seed mixes with the hybrid seed; e) The reduction in the average grain yield in the hybrids studied provoked by mixture of female parent selfed seed were dependent, basically, by the yield and plant vigor of the plant obtained by the selfed seed; the capability of compensation by the other hybrid plants in the plot; d) Using morphologic characteristics, it is possible to separete the selfed plants from the hybrid seed with a good precision for some hybrids. The stage of development better suitable for the evaluation of the genetic purity varies from hybrid to hybrid

Lignification of the plant and seed quality of RR soybeans sprayed with herbicide glyphosate Lignificação da planta e qualidade de sementes de soja RR pulverizadas com herbicida glifosato

Differences in levels of lignin in the plant between conventional and transgenic cultivars RR has been reported by several authors, however, there are few studies evaluating the influence of spraying of glyphosate on the lignin in the plant and RR soybean seeds. The aim of this study was to evaluate the physiological quality of RR transgenic soybean seeds and the lignin contents of plants sprayed with the herbicide glyphosate. The assays were conducted both in greenhouse and field in the municipality of Lavras, MG, in the agricultural year 2007/08. The experiment was arranged in a splitplot design with four replicates, considering the treatments hand weeding and herbicide glyphosate as plots, and five RR soybean cultivars (BRS 245 RR, BRS 247 RR, Valiosa RR, Silvânia RR and Baliza RR) as splitplots. In the greenhouse, the cultivars tested were BRS 245 RR and Valiosa RR in a randomized block design with four replicates. The sprayings were carried out at stages V3, V7 and early R5 (3L/ha). The 1000 seed weight, mechanical injury, germination and germination velocity index, emergence velocity index, accelerated aging, electrical conductivity and water soaking seed test, lignin content in the seed coat, in the stem and legumes were determined. The spraying of glyphosate herbicide, in greenhouse and field, did not alter the physiological quality of seeds and the lignin contents in the plant.Diferenças nos teores de lignina na planta entre cultivares transgênicos RR e convencionais, tem sido relatadas, por vários autores, no entanto, são escassos os trabalhos avaliando a influência da aplicação do glifosato sobre os teores de lignina na planta e em sementes de soja RR. Neste sentido, objetivou-se, com este trabalho, avaliar a qualidade fisiológica de sementes de soja transgênica RR e os teores de lignina de plantas submetidas à pulverização com o herbicida glifosato. Os ensaios foram conduzidos em casa de vegetação e em campo, no município de Lavras, MG, na safra 2007/08. O delineamento experimental, utilizado em campo, foi o de parcelas subdivididas, com quatro repetições, considerando-se como parcelas os tratamentos capina e herbicida glifosato, e, como subparcelas, cinco cultivares RR de soja (BRS 245 RR, BRS 247 RR, Valiosa RR, Silvânia RR e Baliza RR). No ensaio de casa de vegetação, utilizaram-se os cultivares BRS 245 RR e Valiosa RR, em delineamento de blocos casualizados, com quatro repetições. As aplicações com herbicida glifosato foram realizadas nos estádios de desenvolvimento V3, V7 e início de R5 (3 L/ha). Determinou-se o peso de 1000 sementes, dano mecânico, germinação e índice de velocidade de germinação, índice de velocidade de emergência, envelhecimento acelerado, condutividade elétrica e teste de imersão de sementes em água, além dos teores de lignina no tegumento das sementes, no caule e nos legumes. A aplicação do herbicida glifosato, em campo e em casa de vegetação, não alterou a qualidade fisiológica de sementes de soja RR nem os teores de lignina na planta

Physiological analysis and heat-resistant protein (LEA) activity in squash hybrid seeds during development

This study has aimed to evaluate the best time to harvest squash seeds and verify the effect of fruit storage on protein activity and in the physiological quality of 'Jabras' squash hybrid seeds. The fruits were harvested at 15, 30, 45, 60 and 75 days after anthesis (DAA). In every period, thirty fruits were harvested and fifteen had their fruit extracted immediately after harvesting, and the other fifteen fruits were stored for twenty days in plastic boxes under shade conditions, and only after this period the seeds were extracted. Seed quality was evaluated for the following parameters: moisture content, germination, first count, germination rate, seedling emergence, emergence rate, seed mass and seedling dry matter. Also, the electrophoretic profile analysis of heat-resistant proteins (Late Embryogenesis Abundant - LEA) was performed. Seed physiological maturity occurred in fruits harvested at 60 days after anthesis and stored for 20 days. During this period, seeds reached the maximum dry matter, maximum germination and vigor, and a high concentration of LEA proteins

Lignification of the plant and seed quality of RR soybeans sprayed with herbicide glyphosate

Differences in levels of lignin in the plant between conventional and transgenic cultivars RR has been reported by several authors, however, there are few studies evaluating the influence of spraying of glyphosate on the lignin in the plant and RR soybean seeds. The aim of this study was to evaluate the physiological quality of RR transgenic soybean seeds and the lignin contents of plants sprayed with the herbicide glyphosate. The assays were conducted both in greenhouse and field in the municipality of Lavras, MG, in the agricultural year 2007/08. The experiment was arranged in a splitplot design with four replicates, considering the treatments hand weeding and herbicide glyphosate as plots, and five RR soybean cultivars (BRS 245 RR, BRS 247 RR, Valiosa RR, Silvânia RR and Baliza RR) as splitplots. In the greenhouse, the cultivars tested were BRS 245 RR and Valiosa RR in a randomized block design with four replicates. The sprayings were carried out at stages V3, V7 and early R5 (3L/ha). The 1000 seed weight, mechanical injury, germination and germination velocity index, emergence velocity index, accelerated aging, electrical conductivity and water soaking seed test, lignin content in the seed coat, in the stem and legumes were determined. The spraying of glyphosate herbicide, in greenhouse and field, did not alter the physiological quality of seeds and the lignin contents in the plant

Maize heat shock proteins—prospection, validation, categorization and in silico analysis of the different ZmHSP families

Abstract Among the plant molecular mechanisms capable of effectively mitigating the effects of adverse weather conditions, the heat shock proteins (HSPs), a group of chaperones with multiple functions, stand out. At a time of full progress on the omic sciences, they look very promising in the genetic engineering field, especially in order to conceive superior genotypes, potentially tolerant to abiotic stresses (AbSts). Recently, some works concerning certain families of maize HSPs (ZmHSPs) were published. However, there was still a lack of a study that, with a high degree of criteria, would fully conglomerate them. Using distinct but complementary strategies, we have prospected as many ZmHSPs candidates as possible, gathering more than a thousand accessions. After detailed data mining, we accounted for 182 validated ones, belonging to seven families, which were subcategorized into classes with potential for functional parity. In them, we identified dozens of motifs with some degree of similarity with proteins from different kingdoms, which may help explain some of their still poorly understood means of action. Through in silico and in vitro approaches, we compared their expression levels after controlled exposure to several AbSts' sources, applied at diverse tissues, on varied phenological stages. Based on gene ontology concepts, we still analyzed them from different perspectives of term enrichment. We have also searched, in model plants and close species, for potentially orthologous genes. With all these new insights, which culminated in a plentiful supplementary material, rich in tables, we aim to constitute a fertile consultation source for those maize researchers attracted by these interesting stress proteins