RESUMOTêm-se levantado à hipótese de que cultivares de soja RR possuem teores de lignina superiores aos convencionais, o que proporciona maior resistência a danos mecânicos e maior impermeabilidade do tegumento das sementes. Objetivou-se avaliar a qualidade fisiológica e o teor de lignina no tegumento das sementes de soja convencional e RR colhidas em três épocas, em Lavras-MG. Para tanto, as sementes colhidas nos estádios R7, R8 e após 20 dias de retardamento da colheita (R8+20), foram submetidas aos testes para avaliação da qualidade fisiológica e teor de lignina. As cultivares convencionais e RR avaliadas foram: BRS 133 vs BRS 245 RR, BRS 134 vs BRS 247 RR, Conquista vs Valiosa RR, Celeste vs Baliza RR e Jataí vs Silvânia RR. Foram realizados os testes de peso de mil sementes, germinação, envelhecimento acelerado, condutividade elétrica, dano mecânico, índice de velocidade de emergência, germinação após a imersão das sementes em água e teor de lignina no tegumento de sementes. Com exceção do teor de lignina no tegumento de sementes para o contraste Jataí vs Silvânia RR, não foram observadas diferenças entre os materiais RR e convencional, tendo, neste caso, a cv Silvânia RR apresentado resultados superiores aos da convencional. No entanto, houve diferença de comportamento entre os cultivares quanto à tolerância ao retardamento da colheita. Observou-se redução significativa na porcentagem de germinação e vigor das sementes avaliadas com o retardamento da colheita.Termos para indexação: Lignina, deterioração, retardamento de colheita. ABSTRACTOne has raised the hypothesis that the RR soybean cultivars posses lignin contents higher than those of the conventional ones. The present work was conducted with the purpose of evaluating the physiological quality and lignin content in the coat of the conventional and RR soybean seeds collected in three times in Lavras-MG. To that end, the seeds collected at stages R7, R8 and after 20 days of collection delay (R8+20) were submitted to the tests for evaluation of the physiological quality and lignin content. The evaluated conventional and RR cultivars were : BRS 133 vs BRS 245 RR, BRS 134 vs BRS 247 RR, BRS Conquista vs BRS Valiosa RR, BRS Celeste vs BRS Baliza RR and Jataí vs BRS Silvânia RR. The tests of 1000-seed weight, germination, accelerated aging, electrical conductivity, mechanical injury, emergence velocity index, germination after water seed soaking and lignin content in the coat seeds were performed. With the exception of the lignin content in the coat seeds for the contrast Jataí vs Silvânia RR, no differences between the RR and conventional materials were observed, the RR cultivar having presented results superior to those of the conventional one. Nevertheless, there was behavioral difference among the cultivars as to the tolerance to harvest delay. Significant reduction was observed in evaluated germination percentage and vigor of seeds with the collection delay. INTRODUÇÃOO período de viabilidade da semente é extremamente variável, dependendo tanto de cara...

Resumo -O objetivo deste trabalho foi avaliar os efeitos gênicos aditivos e não aditivos para as características da espessura das camadas da testa e da lignina presente nessas camadas, e verifi car se os caracteres utilizados para avaliação da qualidade fi siológica das sementes de soja se correlacionam com o teor de lignina do tegumento. Foram usadas três cultivares (M-Soy 8400, CD 201, CD 206) de alta e três (CD 215, CD 202, Savana) de baixa qualidade fi siológica, para se obterem sementes híbridas F 1 e F 2 , inclusive os recíprocos, pelo sistema de cruzamento dialelo parcial e as linhagens parentais. Os parâmetros primeira contagem de germinação, contagem fi nal de germinação e velocidade de germinação, utilizados para avaliação da qualidade fi siológica, podem ser correlacionados com o teor de lignina. Foram observadas correlações positivas entre o teor de lignina e a percentagem de plântulas normais no teste de envelhecimento ao 5 o e 11 o dias após a semeadura, com valores maiores de correlação no 5 o dia. A correlação entre velocidade de germinação e teor de lignina foi negativa. A análise do dialelo apontou signifi cância do efeito recíproco, o que indica que a espessura das camadas da testa e a espessura de lignina nessas camadas podem ser explicadas pelo efeito materno.Termos para indexação: Glycine max, cruzamento dialélico, lignina, tegumento. Chemical and structural aspects of the physiological quality of soybean seedsAbstract -The objective of this work was to evaluate the additive and non-additive genetic effects for thickness of the seed coat layers and of the lignin present in them, and to verify if the characters used to evaluate the physiological quality of the seeds is correlated with the lignin content. Three cultivars (M-Soy 8400, CD 201, CD 206) with high and three (CD 215, CD 202, Savana) with low physiological quality were used to obtain F 1 and F 2 hybrid seeds, including the reciprocals, using partial diallel crosses and the parental lines. First germination count, fi nal germination count and germination rate, used to evaluate the physiological quality, can be correlated with lignin content. Positive correlations were observed between lignin content and the percentage of normal seedlings in the aging test at the 5 th and 11 th days after sowing, with the highest correlation values at the 5 th day. The correlation between germination rate and lignin content was negative. The diallel analysis showed reciprocal effect, showing that the thickness of the seed coat layers and of the lignin contained in these layers can be explained by maternal effect.Index terms: Glycine max, diallel cross, lignin, seed coat. IntroduçãoA qualidade fi siológica de sementes de soja é em grande parte infl uenciada pelo genótipo. Nos últimos anos, os programas de melhoramento genético têm buscado desenvolver materiais com características como resistência a doenças e pragas, teores de óleo e proteína e, mais recentemente, teor de lignina no tegumento das sementes (Costa et al., 2001).Em algumas pesquisas, tem s...

ABSTRACT. The study of gene expression in plants is fundamental, and understanding the molecular mechanisms involved in important biological processes, such as biochemical pathways or signaling that are used or manipulated in improvement programs, are key for the production of highquality soybean seeds. Reports related to gene expression of lignin in seeds are scarce in the literature. We studied the expression of the phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase, 4-hydroxycinnamate 3-hydroxylase, and cinnamyl alcohol dehydrogenase genes involved in lignin biosynthesis during the development of soybean (Glycine max L. Merrill) seeds. As the endogenous control, the eukaryotic elongation factor 1-beta gene was used in two biological replicates performed in triplicate. Relative quantitative expression of these genes during the R4, R5, R6, and R7 development stages was analyzed. Real-time polymerase chain reaction was used for the gene expression study. The analyses were carried out in an ABI PRISM 7500 thermocycler using the comparative Ct method and SYBR Green to detect amplification. The seed samples at the R4 stage were chosen as calibrators. Increased expression of the cinnamate-4-hydroxylase and PAL genes occurred in soybean seeds at the R5 and R6 development stages. The cinnamyl alcohol dehydrogenase gene was expressed during the ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (3): 2618-2624 (2013 Gene expression of lignin biosynthesis in soybean seeds 2619 final development phases of soybean seeds. In low-lignin soybean cultivars, the higher expression of the PAL gene occurs at development stages R6 and R7. Activation of the genes involved in the lignin biosynthesis pathway occurs at the beginning of soybean seed development.

Soybean seed production with high physiological quality is important for ensuring populations of recommended plants for each cultivar. It is also known that there is genetic variability for this characteristic among the soybean cultivars. The objective was to study the genes expressionof protein and gene transcript involved in the physiological quality of soybean seeds. The seeds of CD 206 and CD 201 cultivars were classified as high quality while Savana and Emgopa 316 cultivars were classified as low quality by germination and vigor tests. Physiological, enzymatic and transcripts analysis were held in seeds of each cultivar during two harvest seasons, R8 and R8 + 15 days; at protein level the alcohol dehydrogenase isoenzyme systems (ADH), phosphoglucoisomerase (PGI), superoxide dismutase (SOD), catalase (CAT), malate dehydrogenase (MDH) and isocitrate lyase (ICL). The PCR technique in real time (qRT-PCR) was used for transcritome studies for quantitative gene expression analysis. The method used was the comparative Ct considering the relative expression levels in relation to cultivar of high quality CD 201. It is concluded that there is higher enzymes expression involved in respiration, alcohol dehydrogenase (ADH), malate dehydrogenase (MDH) and phosphoglucoisomerase (PGI), in seeds with high physiological quality, especially when harvesting is delayed. The proteomic and transcriptomic profiles related to the genes involved in free radicals removing systems in soybeans varies among cultivars and the season of seed harvest.

There has been great speculation about differential responses of transgenic and conventional cultivars of soybean lignin content in its stem, pod and seeds. Each characteristic is associated with the soaking of seeds and pods. Increase of weight of intact soybean seeds and pods at different soaking periods and their relation to the lignin contents in RR and conventional soybean plants was determined. Samples of 20 pods and 50 seeds from the conventional cultivars, Jataí, Celeste, and Conquista and their respective transgenic RR versions Silvânia, Baliza, and Valiosa were utilized. The pods were immersed into water for 1, 3, 6, 9, 12, 24, and 48 h, and the seeds were immersed into water for 1, 2, 3, 4, 5, 6, 7, 9, 12, 24, and 48 h. The intact pods showed some resistance against water in the first few hours of soaking, but the seeds possess greater absorption at the onset and later stabilization. There were no differences between RR transgenic and conventional cultivars for lignin content in stem, leaf, pod, and seed coat and the IVH of intact pods was found. It was difficult to establish an association between the soaking rate and transgenic characteristic in the evaluated soybean cultivars.

Additional information is available at the end of the chapter http://dx.doi.org/10.5772/51353 . IntroductionSoybean Glycine max L. Merrill is one of the most important and most cultivated crops in the world, with significant quantities of proteins being found in their yield composition, around % of their yield dry matter. This expressive quantity of proteins, and also a considerable percentage of oil, around % of their dry matter, has turned this grain into a product of great importance for the industrial sector, whether it be for food, cosmetics or, more recently, biofuels. Thus, soybean breeding programs directed toward these areas become ever more important, together with agronomic characteristics that allow greater productivity in sustainability with the environment in which they are produced.The achievement of soybean genome sequencing [ ], facilitated by identification of the genetic base, lead to advances in obtaining improved cultivars through knowledge of the complete sequence of expressed genes. Nevertheless, this information is not sufficient to identify which proteins are really being expressed in the cell at a given moment and under a certain condition since, through the phenomenon of splicing, different proteins may be produced by alteration of the command of a single gene. Thus, the complementary DNA cDNA and the messenger RNA mRNA have come to be the main focus of study for obtaining information regarding genetic expression or transcriptome. Nevertheless, due to post-translational regulation mechanisms, the quantity of expressed protein is not necessarily proportional to the quantity of its corresponding mRNA, which often raises questions regarding the role of this gene in cellular metabolism.The reason for this is that control of gene expression occurs from mRNA transcription up to post-translational modifications like glycosylation and phosphorylation, among other processes, which alter protein activity Figure .