12 research outputs found
Genetic diversity of breeding popcorn lines determined by SSR markers
Information about genetic dissimilarity is very important to
corroborate genealogical relationships and to predict the most
heterozygotic hybrid combinations. Eight popcorn S6 lines of diverse
germplasm types were evaluated using simple sequence repeats (SSR)
markers. Of a total of 51 evaluated polymorphic primers, 15 were used
for polymerase chain reaction (PCR) amplification. The genetic distance
was estimated by Rogers' modified distance. The different popcorn
breeding programs in Brazil are possibly using highly similar
base-populations. The genetic similarity of lines P1-3 and P8-1 was
lowest, while P3-3 and P8-2 were genetically more similar. The
cophenetic correlation showed that the Unweighted Pair-Group Method
Using Arithmetic Averages (UPGMA) was reliable to discriminate the
genotypes in five groups. The clusters were consistent with the
estimates of genetic identity. There was a moderate coincidence degree
between the groups and genealogy of lines. Higher levels of
heterozygosity are expected from crosses between the group containing
lines P3-3 and P7-3 with that of P1-3 and P7-4. Crosses between lines
P1-3 and P8-1 are also promising
Tissue culture of ornamental cacti
Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family
Genetic diversity of breeding popcorn lines determined by SSR markers
Information about genetic dissimilarity is very important to
corroborate genealogical relationships and to predict the most
heterozygotic hybrid combinations. Eight popcorn S6 lines of diverse
germplasm types were evaluated using simple sequence repeats (SSR)
markers. Of a total of 51 evaluated polymorphic primers, 15 were used
for polymerase chain reaction (PCR) amplification. The genetic distance
was estimated by Rogers' modified distance. The different popcorn
breeding programs in Brazil are possibly using highly similar
base-populations. The genetic similarity of lines P1-3 and P8-1 was
lowest, while P3-3 and P8-2 were genetically more similar. The
cophenetic correlation showed that the Unweighted Pair-Group Method
Using Arithmetic Averages (UPGMA) was reliable to discriminate the
genotypes in five groups. The clusters were consistent with the
estimates of genetic identity. There was a moderate coincidence degree
between the groups and genealogy of lines. Higher levels of
heterozygosity are expected from crosses between the group containing
lines P3-3 and P7-3 with that of P1-3 and P7-4. Crosses between lines
P1-3 and P8-1 are also promising
Parâmetros genéticos de caracteres relacionados à tolerância à deficiência hídrica em milho tropical Genetic parameters of drought tolerance related traits in tropical maize
A seleção de caracteres relacionados à tolerância à deficiência hídrica em milho tem sido objeto de interesse em programas de melhoramento, principalmente em virtude da ineficiência da seleção para produzir grãos nessas condições. O objetivo deste trabalho foi estimar parâmetros genéticos em duas populações de milho tropical. Foram avaliadas duas populações (denominadas D e U) com 256 progênies F2:3, no delineamento em látice 16 x 16 em sete ou nove ambientes e densidade populacional de 62.500 plantas ha-1. Diferenças significativas foram constatadas entre progênies (P), ambientes (A) e para a interação P x A em ambas as populações. Os coeficientes de herdabilidade em nível de médias de progênies variaram entre 73,52% para prolificidade na população D e 95,88% para florescimento feminino (FF) na população U. No caráter produção de grãos (PG) houve correlação genética significativa nas populações U e D, respectivamente, com prolificidade (0,79 e 0,88) e florescimento feminino (-0,76 e -0,44); na população U com florescimento masculino (-0,74) e; na população D com stay-green (-0,50). Não foi constatada correlação genética significativa entre PG e intervalo entre florescimentos (IF). Os parâmetros genéticos estimados sugerem que a utilização de índices de seleção que incluam, além de PG, caracteres como prolificidade, FF e SG na seleção de progênies sob condições normais de umidade, poderia propiciar o desenvolvimento de material com alta produtividade e boa tolerância a estresses hídricos.<br>The selection of drought tolerance related traits in maize has been object of interest in improvement programs, mainly in function of the selection inefficiency for grain yield on these conditions. The objective of this work was to estimate genetic parameters in two populations of tropical maize. Two populations (called D and U) with 256 F2:3 progenies had been evaluated in a 16x16 simple lattice, in seven and nine environments with population density of 62,500 plants ha-1. Significant differences were observed among line (P), environments (A) and for the P x A interaction in both populations. The heritability coefficients at progenies level average had varied between 73.52% for prolificacy in population D and 95.88% for female flowering (FF) in population U. Grain yield (PG) presented significant genetic correlation in populations U and D, respectively, with prolificacy (0,79 and 0.88) and female flowering (-0,76 and -0,44); in population U with male flowering (-0.74) and; in population D with stay-green (-0.50). No genetic correlation was observed between PG and anthesis-silking interval (IF). Estimated of genetic parameters suggest that the use of selection indices that include, besides PG, characters as prolificacy, FF and SG in the selection process under conditions of normal water supply, could lead to the development of cultivars with high grain yield and good drought tolerance
Esterase polymorphism in remanant populations of Aspidosperma polyneuron Müll.Arg. (Apocynaceae) Polimorfismo de esterases em populações remanescentes de Aspidosperma polyneuron Müll.Arg. (Apocynaceae)
The population genetic structure of the endangered tree species Aspidosperma polyneuron Mull.Arg. (Apocynaceae) was reported based on analysis of esterase polymorphism in two remanant populations. Allelic variation was detected at three isoesterase loci (Est-3, Est-9, and Est-10). The proportion of polymorphic loci for both populations was 30% and deviation from Hardy-Weinberg equilibrium was observed for the Est-3 locus observed in the northern population. Segregation distortion and the lower level of observed and expected heterozygosity in this population were attributed to founder genotype. The high genetic identity values for northern and northwestern populations are in accordance with the low levels of interpopulation genetic divergence demonstrated by the F(ST) (0.03) value. The F(IS) value (0.23) indicated moderate levels of inbreeding. A. polyneuron can be indicated as an example of endangered species suggesting high genetic variation in contrast to the low genetic variation reported for endangered species. The esterase isozymes may be a good genetic marker for studies of natural A. polyneuron populations.<br>A análise do polimorfismo de isozimas esterases foi usada para reportar a estrutura genética de duas populações remanecentes da espécie de árvore em extinção Aspidosperma polyneuron Müll.Arg. (Apocynaceae). Variação alélica foi detectada em três locos de isoesterases (Est-3, Est-9, e Est-10). A proporção de locos polimórficos de ambas as populações foi de 30%, sendo observado um desvio do equilíbrio de Hardy-Weinberg no loco Est-3 na população da região norte do Estado do Paraná. Uma distorção na segregação e um mais baixo nível de heterozigosidade observada e esperada nesta população foram atribuídos ao efeito do genótipo fundador. Os valores altos de identidade genética das populações do norte e noroeste do Estado estão de acordo com o baixo nível de divergência genética interpopulacional demonstrado pelo valor de F(ST) (0,03). O valor de F(IS) (0,23) indicou moderado nível de endocruzamentos. A. polyneuron pode ser indicada como um exemplo de espécie em extinção apresentando variação genética alta, contrastando com a variação genética baixa reportada sobre espécies em extinção. As isozimas esterases podem ser um bom marcador genético em estudos de populações naturais de A. polyneuron