Reciprocal recurrent selection effects on the genetic structure of tropical maize populations assessed at microsatellite loci

A modified reciprocal recurrent selection (RRS) method, which employed one cycle of high-intensity selection, was applied to two tropical maize (Zea mays L.) populations, BR-105 and BR-106, originating the improved synthetics IG-3 and IG-4, respectively. In the present study the effects of this kind of selection on the genetic structure of these populations and their synthetics were investigated at 30 microsatellite (SSR) loci. A total of 125 alleles were revealed. A reduction in the number of alleles was observed after selection, as well as changes in allele frequencies. In nearly 13% (BR-105) and 7% (BR-106) of the loci evaluated, the changes in allele frequencies were not explained, exclusively due to the effects of genetic drift. The effective population sizes estimated for the synthetics using 30 SSR loci were similar to those theoretically expected after selection. The genetic differentiation (G ST) between the synthetics increased to 77% compared with the original populations. The estimated R ST values, a genetic differentiation measure proper for microsatellite data, were similar to those obtained for G ST. Despite the high level of selection applied, the total gene diversity found in the synthetics allows them to be used in a new RRS cycle.355364Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Variabilidade isoenzimática em populações tropicais de milho sob seleção recorrente recíproca

O milho (Zea mays L.) é uma das culturas em que a variabilidade genética tem sido extensivamente estudada com base em locos isoenzimáticos. A variabilidade genética das populações de milho BR-105 e BR-106, e dos sintéticos IG-3 e IG-4, obtidos após um ciclo de seleção recorrente de elevada intensidade, foi investigada para sete locos isoenzimáticos. Foram identificados 20 alelos, sendo que a maioria dos alelos exclusivos foi detectada na população BR-106. Um ciclo de seleção recorrente recíproca (RRS) causou reduções de 12% no número de alelos em ambas populações. Mudanças nas freqüências alélicas foram observadas entre populações e sintéticos, principalmente para o loco Est 2. As populações mostraram similaridade para número de alelos por loco, porcentagem de locos polimórficos, e para heterozigosidade observada e esperada. Houve decréscimo nas estimativas da variabilidade dos sintéticos em conseqüência dos efeitos da deriva genética e redução do tamanho efetivo populacional. A distribuição da diversidade genética dentro e entre as populações revelou que a maior parte da diversidade permaneceu dentro delas, i.e. BR-105 x BR-106 (G ST = 3,5%) e IG-3 x IG-4 (G ST = 4,0%). A distância genética entre as populações e os sintéticos aumentou em torno de 21%. Houve aumento na divergência genética entre as populações, porém sem comprometer novos procedimentos de seleção.Maize (Zea mays L.) is one of the crops in which the genetic variability has been extensively studied at isoenzymatic loci. The genetic variability of the maize populations BR-105 and BR-106, and the synthetics IG-3 and IG-4, obtained after one cycle of a high-intensity reciprocal recurrent selection (RRS), was investigated at seven isoenzymatic loci. A total of twenty alleles were identified, and most of the private alleles were found in the BR-106 population. One cycle of reciprocal recurrent selection (RRS) caused reductions of 12% in the number of alleles in both populations. Changes in allele frequencies were also observed between populations and synthetics, mainly for the Est 2 locus. Populations presented similar values for the number of alleles per locus, percentage of polymorphic loci, and observed and expected heterozygosities. A decrease of the genetic variation values was observed for the synthetics as a consequence of genetic drift effects and reduction of the effective population sizes. The distribution of the genetic diversity within and between populations revealed that most of the diversity was maintained within them, i.e. BR-105 x BR-106 (G ST = 3.5%) and IG-3 x IG-4 (G ST = 4.0%). The genetic distances between populations and synthetics increased approximately 21%. An increase in the genetic divergence between the populations occurred without limiting new selection procedures

Transcriptomic analysis of changes in gene expression during flowering induction in sugarcane under controlled photoperiodic conditions

Flowering is of utmost relevance for the agricultural productivity of the sugarcane bioeconomy, but data and knowledge of the genetic mechanisms underlying its photoperiodic induction are still scarce. An understanding of the molecular mechanisms that regulate the transition from vegetative to reproductive growth in sugarcane could provide better control of flowering for breeding. This study aimed to investigate the transcriptome of +1 mature leaves of a sugarcane cultivar subjected to florally inductive and non-inductive photoperiodic treatments to identify gene expression patterns and molecular regulatory modules. We identified 7,083 differentially expressed (DE) genes, of which 5,623 showed significant identity to other plant genes. Functional group analysis showed differential regulation of important metabolic pathways involved in plant development, such as plant hormones (i.e., cytokinin, gibberellin, and abscisic acid), light reactions, and photorespiration. Gene ontology enrichment analysis revealed evidence of upregulated processes and functions related to the response to abiotic stress, photoprotection, photosynthesis, light harvesting, and pigment biosynthesis, whereas important categories related to growth and vegetative development of plants, such as plant organ morphogenesis, shoot system development, macromolecule metabolic process, and lignin biosynthesis, were downregulated. Also, out of 76 sugarcane transcripts considered putative orthologs to flowering genes from other plants (such as Arabidopsis thaliana, Oryza sativa, and Sorghum bicolor), 21 transcripts were DE. Nine DE genes related to flowering and response to photoperiod were analyzed either at mature or spindle leaves at two development stages corresponding to the early stage of induction and inflorescence primordia formation. Finally, we report a set of flowering-induced long non-coding RNAs and describe their level of conservation to other crops, many of which showed expression patterns correlated against those in the functionally grouped gene network

Gene Duplication in the Sugarcane Genome: A Case Study of Allele Interactions and Evolutionary Patterns in Two Genic Regions

Sugarcane (Saccharum spp.) is highly polyploid and aneuploid. Modern cultivars are derived from hybridization between S. officinarum and S. spontaneum. This combination results in a genome exhibiting variable ploidy among different loci, a huge genome size (~10 Gb) and a high content of repetitive regions. An approach using genomic, transcriptomic, and genetic mapping can improve our knowledge of the behavior of genetics in sugarcane. The hypothetical HP600 and Centromere Protein C (CENP-C) genes from sugarcane were used to elucidate the allelic expression and genomic and genetic behaviors of this complex polyploid. The physically linked side-by-side genes HP600 and CENP-C were found in two different homeologous chromosome groups with ploidies of eight and ten. The first region (Region01) was a Sorghum bicolor ortholog region with all haplotypes of HP600 and CENP-C expressed, but HP600 exhibited an unbalanced haplotype expression. The second region (Region02) was a scrambled sugarcane sequence formed from different noncollinear genes containing partial duplications of HP600 and CENP-C (paralogs). This duplication resulted in a non-expressed HP600 pseudogene and a recombined fusion version of CENP-C and the orthologous gene Sobic.003G299500 with at least two chimeric gene haplotypes expressed. It was also determined that it occurred before Saccharum genus formation and after the separation of sorghum and sugarcane. A linkage map was constructed using markers from nonduplicated Region01 and for the duplication (Region01 and Region02). We compare the physical and linkage maps, demonstrating the possibility of mapping markers located in duplicated regions with markers in nonduplicated region. Our results contribute directly to the improvement of linkage mapping in complex polyploids and improve the integration of physical and genetic data for sugarcane breeding programs. Thus, we describe the complexity involved in sugarcane genetics and genomics and allelic dynamics, which can be useful for understanding complex polyploid genomes

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Genetic structure of maize (Zea mays L.) populations BR-105 and BR-106 and their synthetics IG-3 and IG-4 BY microsatellite markers

Microssatélites foram utilizados para avaliar a estrutura genética das populações de milho BR-105, BR-106 e respectivos sintéticos IG-3 e IG-4 obtidos após um ciclo de seleção recorrente recíproca de elevada intensidade. Foram utilizados 30 locas de microssatélites, os quais, revelaram um total de 125 alelos distribuídos entre as populações e os sintéticos. Uma redução no número de alelos foi observada nos sintéticos IG-3 (23%) e IG-4 (17%). O teste de diferenciação das freqüências alélicas em relação a: BR-105 x BR-106, IG-3 x IG-4, BR-105 x IG-3 e BR-106 x IG-4 foi significativo (P 0,05). A diversidade gênica total foi similar nas populações, ambas com valores altos. Nos sintéticos, a diversidade gênica total não foi significativamente diferente da esperada teoricamente sob o modelo de deriva genética, indicando que as perdas de variabilidade genética podem ser atribuídas aos efeitos da deriva genética provocados pelo tamanho efetivo populacional reduzido. Os tamanhos efetivos populacionais estimados para ambos sintéticos com base nos 30 locos de microssatélites mostraram valores próximos aos teoricamente esperados. O índice de diferenciação genética G&#770ST aumentou cerca de 77% das populações (G&#770ST = 11,00%) para os sintéticos (G&#770ST = 19,50). Os valores R&#770ST estimados foram semelhantes aos obtidos pelo G&#770ST nas análises da partição da diversidade. A distância genética de Nei foi de 18,6% entre as populações BR-105 e BR-106 e de 24,1% entre os sintéticos IG-3 e IG-4. A distância (&#948;&#181;)2 foi superior à distância de Nei: 26,7% entre BR-105 e BR-106, e 36,1% entre IG-3 e IG-4. O nível de diversidade gênica total encontrado nos sintéticos, suporta a sua utilização em um novo ciclo de seleção recorrente recíproca.Microsatellites were used to evaluate the genetic structure of the maize populations BR-105, BR-106 and their synthetics IG-3 and IG-4, obtained after one cycle of reciprocal recurrent selection with high intensities over the original populations. Thirty microsatellite loci were examined. A total of 125 alleles were identified, and distributed among the populations and their synthetics. Reductions in the number of alleles were observed in the synthetics IG-3 (23%) and IG-4 (17%). The population differentiation tests concerning the allele frequencies in relation to BR-105 x BR-106, IG-3 x IG-4, BR-105 x IG-3 and BR-106 x IG-4 were significant for most of the loci (P 0.05). The total gene diversity was similar in the populations and both presented high values. In the synthetics, the total gene diversity was not different from the theoretical expectations under the genetic drift model, so the loss of genetic variability can be attributed to the effects of random genetic drift caused by the effective population size. The effective population size estimated from 30 microsatellite loci for both synthetics were very similar to the predicted. The differentiation index (G&#770ST) increased 77% from the original populations (G&#770ST = 11%) to their synthetics (G&#770ST = 19,5%). The R&#770ST values were very similar to those obtained by G&#770ST in the partition of genetic analysis. The value of Nei's genetic distance was 18,6% between BR-105 and BR-106, and 24,1 % between IG-3 and IG-4. The distance (&#948;&#181;)2 was higher than Nei's: 26,7% between BR-105 and BR-106 and 36% between IG-3 and IG-4. The total gene diversity assessed support their use in a new cycle of reciprocal recurrent selection

Composição química, sanidade, secagem e germinação de sementes de ipê-branco (Tabebuia roseo-alba (Ridl.) Sand.- Bignoniaceae)

O ipê-branco (Tabebuia roseo-alba) é uma espécie arbórea nativa do Brasil que, além de outros valores, possui grande potencial ornamental. Existem poucas informações a respeito de suas sementes; assim, o presente trabalho foi realizado com o objetivo de determinar a composição química e detectar os fungos associados às sementes, bem como estudar o efeito de diferentes métodos de secagem na redução do grau de umidade e na germinação das sementes. As sementes foram colhidas de 25 árvores localizadas no campus da FCAV-UNESP em Jaboticabal (SP). O resultado das análises químicas mostrou que as sementes de ipê-branco são constituí-' das de 22,5% de proteínas, 18,6% de lipídios e 7,6% de carboidratos, e a análise de sanidade revelou que as sementes estavam contaminadas com fungos de vários gêneros, principalmente do gênero Fusarium. As sementes foram submetidas à secagem em liofilizador, em câmara seca e em estufa, tendo sido determinados o grau de umidade e a porcentagem de germinação imediatamente antes e depois da secagem. Os resultados obtidos mostraram que os métodos de secagem testados foram eficientes para reduzir o grau de umidade, mas prejudicaram a capacidade germinativa das sementes

Composição química, sanidade, secagem e germinação de sementes de ipê-branco (Tabebuia roseo-alba (Ridl.) Sand.- Bignoniaceae)

O ipê-branco (Tabebuia roseo-alba) é uma espécie arbórea nativa do Brasil que, além de outros valores, possui grande potencial ornamental. Existem poucas informações a respeito de suas sementes; assim, o presente trabalho foi realizado com o objetivo de determinar a composição química e detectar os fungos associados às sementes, bem como estudar o efeito de diferentes métodos de secagem na redução do grau de umidade e na germinação das sementes. As sementes foram colhidas de 25 árvores localizadas no campus da FCAV-UNESP em Jaboticabal (SP). O resultado das análises químicas mostrou que as sementes de ipê-branco são constituí-' das de 22,5% de proteínas, 18,6% de lipídios e 7,6% de carboidratos, e a análise de sanidade revelou que as sementes estavam contaminadas com fungos de vários gêneros, principalmente do gênero Fusarium. As sementes foram submetidas à secagem em liofilizador, em câmara seca e em estufa, tendo sido determinados o grau de umidade e a porcentagem de germinação imediatamente antes e depois da secagem. Os resultados obtidos mostraram que os métodos de secagem testados foram eficientes para reduzir o grau de umidade, mas prejudicaram a capacidade germinativa das sementes

Isoenzymatic variability in tropical maize populations under reciprocal recurrent selection

Maize (Zea mays L.) is one of the crops in which the genetic variability has been extensively studied at isoenzymatic loci. The genetic variability of the maize populations BR-105 and BR-106, and the synthetics IG-3 and IG-4, obtained after one cycle of a high-intensity reciprocal recurrent selection (RRS), was investigated at seven isoenzymatic loci. A total of twenty alleles were identified, and most of the private alleles were found in the BR-106 population. One cycle of reciprocal recurrent selection (RRS) caused reductions of 12% in the number of alleles in both populations. Changes in allele frequencies were also observed between populations and synthetics, mainly for the Est 2 locus. Populations presented similar values for the number of alleles per locus, percentage of polymorphic loci, and observed and expected heterozygosities. A decrease of the genetic variation values was observed for the synthetics as a consequence of genetic drift effects and reduction of the effective population sizes. The distribution of the genetic diversity within and between populations revealed that most of the diversity was maintained within them, i.e. BR-105 x BR-106 (G ST = 3.5%) and IG-3 x IG-4 (G ST = 4.0%). The genetic distances between populations and synthetics increased approximately 21%. An increase in the genetic divergence between the populations occurred without limiting new selection procedures