Diversity and genetic structure among subpopulations of Gossypium mustelinum (Malvaceae).

Gossypium mustelinum is the only cotton species native to Brazil; it is endemic to the semi-arid region of the northeast. The populations are found near perennial and semi-perennial sources of water, such as ponds or pools in intermittent streams. Problems with in situ conservation derive from human interference in its habitat, mainly because of excessive cattle grazing and deforestation. Establishing efficient strategies for in situ conservation requires knowledge of the genetic structure of the populations. We evaluated the structure and genetic variability of populations of G. mustelinum in the Tocó and Capivara Rivers (State of Bahia). Two hundred and eighteen mature G. mustelinum plants were genotyped with SSR markers. The molecular data were used to estimate the allelic frequencies, the heterozygosity, the F statistics, and the genetic distance among the populations and among individuals. We found high genetic diversity among the populations. The FST indexes for each population were also high and strongly correlated with physical distance. The high estimated level of endogamy and the low observed heterozygosity are indicative that the populations reproduce mainly by self-fertilization and crosses between related individuals. Consequently, strategies for in situ preservation should include at least three occurrence sites of G. mustelinum from each population. For ex situ conservation, the collections should include as many sites as possible.

Effect of arbuscular mycorrhizal fungi and soil phosphorus level on expression of protein and activity of peroxidase on passion fruit roots.

The effects of mycorrhizal inoculation and increasing soil P levels on the expression of total proteins and peroxidase activity on passion fruit roots were evaluated. The experimental design was entirely at random, with four treatments of inoculation (a--control; b--Gigaspora albida; c--Scutellospora heterogama; d--mixture of G. albida, G. margarita, S. heterogama, and Glomus clarum) x three levels of soil P (4, 11, and 30 mg/dm3 of soil), each with three replicates. Plants were harvested 70 days after inoculation, when root colonization, shoot P level, protein content, and enzymatic activity of peroxidase (PAGE--7%) on root extract were evaluated. Regarding protein, there was no significant difference among the treatments, except between those roots receiving mixed inoculum and 11 mg P/dm3 of soil. Effect of P on protein concentration, when compared with the inoculation effect was observed. For peroxidase, there was an eletrophoretic band common to all treatments (rf: 0.43) and another that was absent only in noncolonized plants, grown in soil with lower P (rf: 0.46). Mycorrhizal specific bands were not present but a small decrease of intensity of bands in noncolonized plants was observed. Conversely, the control roots presented a single band (rf: 0.33) not observed in the other extracts, that may demonstrate an inhibitory effect of AMF on some host activities. The data showed the influence of P level in soil on the protein expression of roots, suggesting the influence of this nutrient on root genetic expression as well as on the mechanisms of symbiotic control/recognition.

Effect of arbuscular mycorrhizal fungi and soil phosphorus level on expression of protein and activity of peroxidase on passion fruit roots

The effects of mycorrhizal inoculation and increasing soil P levels on the expression of total proteins and peroxidase activity on passion fruit roots were evaluated. The experimental design was entirely at random, with four treatments of inoculation (a - control; b - Gigaspora albida; c - Scutellospora heterogama; d - mixture of G. albida, G. margarita, S. heterogama, and Glomus clarum) × three levels of soil P (4, 11, and 30 mg/dm³ of soil), each with three replicates. Plants were harvested 70 days after inoculation, when root colonization, shoot P level, protein content, and enzymatic activity of peroxidase (PAGE - 7%) on root extract were evaluated. Regarding protein, there was no significant difference among the treatments, except between those roots receiving mixed inoculum and 11 mg P/dm³ of soil. Effect of P on protein concentration, when compared with the inoculation effect was observed. For peroxidase, there was an eletrophoretic band common to all treatments (rf: 0.43) and another that was absent only in noncolonized plants, grown in soil with lower P (rf: 0.46). Mycorrhizal specific bands were not present but a small decrease of intensity of bands in noncolonized plants was observed. Conversely, the control roots presented a single band (rf: 0.33) not observed in the other extracts, that may demonstrate an inhibitory effect of AMF on some host activities. The data showed the influence of P level in soil on the protein expression of roots, suggesting the influence of this nutrient on root genetic expression as well as on the mechanisms of symbiotic control/recognition.

O efeito da inoculação micorrízica e de crescentes níveis de P no solo sobre a expressão de proteínas e a atividade da peroxidase foi avaliado em raízes de maracujazeiro-amarelo (Passiflora edulis f. flavicarpa Deg.). O arranjo experimental foi feito totalmente ao acaso com quatro tratamentos de inoculação com fungos micorrízicos arbusculares, FMA (a - controle, b - Gigaspora albida, c - Scutellospora heterogama e d - mistura de G. albida, S. heterogama, G. margarita e Glomus clarum) × três níveis de P no solo (4, 11 e 30 mg/dm³ de solo) com três repetições. As plantas foram colhidas aos 70 dias de inoculação, para avaliação da colonização micorrízica, determinação do P na parte aérea, estimativa do conteúdo protéico e avaliação da atividade enzimática da peroxidase (em gel de poliacrilamida - PAGE - 7%) nos extratos radiculares. Nos valores de proteína, não houve diferença significativa, exceto entre as raízes tratadas com inóculo misto e 11 mg de P/dm³ de solo e as plantas crescidas com G. albida em solo com 30 mg de P/dm³ de solo. Observou-se influência destacada do P sobre a concentração protéica, quando comparado com o efeito fúngico. Para peroxidase, evidenciou-se a formação de uma banda eletroforética comum a todos os tratamentos (rf: 0,43) e outra que foi ausente apenas nas plantas não colonizadas, crescidas em solo com menores concentrações de P (rf: 0,46). Não foram notadas bandas micorrízicas específicas nos extratos, mas uma pequena diminuição na intensidade em bandas de plantas não colonizadas. Porém, a raiz controle apresentou uma banda única (rf: 0,33), não presente nos demais extratos, o que demonstra, talvez, um efeito inibitório dos FMA sobre algumas atividades do hospedeiro. Os dados demonstram a influência do nível de P no solo sobre a expressão protéica radicular, sugerindo a influência desse elemento na expressão gênica radicular, bem como nos mecanismos de controle/reconhecimento simbiótico.

Effect of arbuscular mycorrhizal fungi and soil phosphorus level on expression of protein and activity of peroxidase on passion fruit roots

The effects of mycorrhizal inoculation and increasing soil P levels on the expression of total proteins and peroxidase activity on passion fruit roots were evaluated. The experimental design was entirely at random, with four treatments of inoculation (a - control; b - Gigaspora albida; c - Scutellospora heterogama; d - mixture of G. albida, G. margarita, S. heterogama, and Glomus clarum) Ãù three levels of soil P (4, 11, and 30 mg/dm of soil), each with three replicates. Plants were harvested 70 days after inoculation, when root colonization, shoot P level, protein content, and enzymatic activity of peroxidase (PAGE - 7 percent) on root extract were evaluated. Regarding protein, there was no significant difference among the treatments, except between those roots receiving mixed inoculum and 11 mg P/dm of soil. Effect of P on protein concentration, when compared with the inoculation effect was observed. For peroxidase, there was an eletrophoretic band common to all treatments (rf: 0.43) and another that was absent only in noncolonized plants, grown in soil with lower P (rf: 0.46). Mycorrhizal specific bands were not present but a small decrease of intensity of bands in noncolonized plants was observed. Conversely, the control roots presented a single band (rf: 0.33) not observed in the other extracts, that may demonstrate an inhibitory effect of AMF on some host activities. The data showed the influence of P level in soil on the protein expression of roots, suggesting the influence of this nutrient on root genetic expression as well as on the mechanisms of symbiotic control/recognition