Regulatory Frameworks for the Access and Use of Genetic Resources in Latin America.

The Nagoya Protocol is a legal framework focused on the Access and Benefit Sharing of genetic resources, including Biological Control Agents. In order to comply with the Nagoya Protocol, countries in Latin America are establishing legal frameworks for access to genetic resources. Scientists face the challenges of the bureaucratic and administrative burden to obtain the access permits to study the biodiversity present in Latin American countries, which include the evaluation of biological control agents that can be used in sustainable production programs. In order to avoid the demotivation of scientists and students to work on biological control by blocking the opportunities to get new bioproducts, it is important to increase the communication between the regulatory authorities and the scientific community, to ensure the establishment of an effective structure and mechanisms to facilitate the process and reduce the time needed to obtain the access permits. On the other hand, the establishment of regional platforms for the exchange of information and harmonization of procedures can contribute to reinforce the collaboration among Latin American countries and facilitate regional studies and biocontrol activities. In this article, the legal framework in place in different countries in Latin America will be discussed and some possible solutions and ways forward to the major challenges observed will be presented.

The sensitivity of sunflower (Helianthus annuus L.) plants to UV-B radiation is altered by nitrogen status / A sensibilidade das plantas de girassol (Helianthus annuus L.) à radiação UV-B é alterada pelo suprimento de nitrogênio

ABSTRACT: Interaction effects between nitrogen and UV-B radiation were studied in sunflower (Helianthus annuus L. variety IAC-Iarama) plants grown in a greenhouse under natural photoperiod conditions. Plants were irradiated with 0.8W m-2 (control) or 8.0W m-2 (+UV-B) of UV-B radiation for 7h per day. The plants were grown in pots containing vermiculite and watered with 70% of full strength nitrogen-free Long Ashton solution, containing either low (42.3ppm) or high (282ppm) nitrogen as ammonium nitrate. High nitrogen increased dry matter of stem, leaves and shoot, photosynthetic pigments and photosynthesis (A) without any alteration in stomatal conductance (gs) nor transpiration (E) while it reduced the intercellular CO2 (Ci) concentration, and malondialdehyde (MDA) content. High UV-B radiation had negative effects on dry matter production, A, gs and E with the effects more marked under high nitrogen, whereas it increased Ci under high nitrogen. Activity of PG-POD was reduced by high UV-B radiation under low nitrogen but it was not changed under high nitrogen. The UV-B radiation increased the MDA content independently of nitrogen level. Results indicate that the effects of UV-B radiation on sunflower plants are dependent of nitrogen supply with high nitrogen making their physiological processes more sensitive to UV-B radiation.

RESUMO: Os efeitos da interação entre nitrogênio e a radiação UV-B foram estudados em plantas de girassol (Helianthus annuus L. variedade IAC-Iarama), cultivadas em casa de vegetação sob condições fotoperiódicas naturais. As plantas foram irradiadas com 0.8W m-2 (controle) ou 8.0W m-2 (+UV-B) durante 7h por dia. As plantas foram cultivadas em vasos contendo vermiculita e regadas com solução nutritiva de Long Ashton 70%, contendo baixa (42,3ppm) ou alta (282ppm) dose de nitrogênio na forma de nitrato de amônio. A alta dose de nitrogênio aumentou a matéria seca das folhas, caule e parte aérea, pigmentos fotossintéticos e a fotossíntese (A), sem alterar a condutância estomática (gs) ou transpiração (E), enquanto reduziu a concentração intercelular de CO2 (Ci) e o conteúdo de malondialdeído (MDA). A elevada radiação UV-B reduziu a produção de matéria seca, A, gs e E, sendo os efeitos mais acentuados sob alta dose de nitrogênio, enquanto aumentou Ci sob alta dose de nitrogênio. A atividade da PG-POD foi reduzida sob alta radiação UV-B e baixo nitrogênio, mas não foi alterada sob alta dose de nitrogênio. A radiação UV-B aumentou o conteúdo de MDA independente do nitrogênio. Os resultados indicam que os efeitos da radiação UV-B em plantas de girassol são dependentes da disponibilidade de nitrogênio sendo que a alta dose de nitrogênio torna seus processos fisiológicos mais sensíveis à radiação UV-B.

Detecção da tolerância de diferentes espécies de capim-colchão a herbicidas inibidores do fotossistema II utilizando a técnica da fluorescência / Detection of crabgrass species tolerance to photosystem II inhibitor herbicides using fluorescence technique

Este estudo teve como objetivo investigar a tolerância ou susceptibilidade das espécies de capim-colchão (Digitaria ciliaris, D. horizontalis e D. nuda) a herbicidas inibidores do fotossistema II (FSII), por meio da técnica da fluorescência, utilizando a taxa de transferência de elétrons do FSII como indicador. Para isso, foi conduzido um experimento em esquema fatorial 3x6, com três espécies de capim-colchão e seis tratamentos (ametryn, hexazinone, diuron+hexazinone, amicarbazone, diuron, tebuthiuron e testemunha) aplicados em pós-emergência. Foi monitorada a taxa de transporte de elétrons (ETR) do FSII em intervalos de tempo crescente e aferida a massa seca das plantas aos 21 dias após a aplicação. A partir dos dados da ETR, calculou-se um valor numérico representativo da taxa de inativação da ETR. Os resultados demonstraram que todas as espécies de capim-colchão estudadas são susceptíveis aos herbicidas ametryn e hexazinone (valores da taxa de inativação da ETR superiores a 10.000). Os herbicidas diuron e tebuthiuron apresentaram menores taxas de inativação da ETR para a D. nuda (3.585 e 3.497, respectivamente) e maiores para as espécies D. ciliaris e D. horizontalis (acima de 10.000), enquanto que o herbicida amicarbazone apresentou valor intermediário para D. nuda (7.967). O monitoramento da ETR foi eficiente para verificar a atuação dos herbicidas nas diferentes espécies estudadas.

This study aimed to investigate the tolerance or susceptibility of crabgrass species (Digitaria ciliaris, D. horizontalis and D. nuda) to herbicides that target photosystem II (PSII), by fluorescence technique using the electron transport rate (ETR) through PSII as an indicator. An experiment was conducted under a factorial arrange (3x6), with three species of crabgrass and six treatments (ametryn, hexazinone, diuron+hexazinone, amicarbazone, diuron, tebuthiuron and control) applied in post-emergence. The ETR through PSII was monitored over time and the plants dry weight measured at 21 days after application. A numerical value of the ETR inactivation was calculated from the data collected. The results showed that the three crabgrass species studied are susceptible to ametryn and hexazinone (ETR inactivation value higher than 10,000). Moreover, diuron and tebuthiuron provided lower ETR inactivation for D. nuda (3,585 and 3,497, respectively) and higher rates for D. horizontalis and D. ciliaris (more than 10,000), whereas amicarbazone showed intermediate inactivation rate for D. nuda (7,967). Monitoring the ETR showed to be an efficient form to verify the herbicides performance in the different species studied here.

Novel bioassay for the discovery of inhibitors of the 2-C-methyl-D-erythritol 4-phosphate (MEP) and terpenoid pathways leading to carotenoid biosynthesis.

The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway leads to the synthesis of isopentenyl diphosphate in plastids. It is a major branch point providing precursors for the synthesis of carotenoids, tocopherols, plastoquinone and the phytyl chain of chlorophylls, as well as the hormones abscisic acid and gibberellins. Consequently, disruption of this pathway is harmful to plants. We developed an in vivo bioassay that can measure the carbon flow through the carotenoid pathway. Leaf cuttings are incubated in the presence of a phytoene desaturase inhibitor to induce phytoene accumulation. Any compound reducing the level of phytoene accumulation is likely to interfere with either one of the steps in the MEP pathway or the synthesis of geranylgeranyl diphosphate. This concept was tested with known inhibitors of steps of the MEP pathway. The specificity of this in vivo bioassay was also verified by testing representative herbicides known to target processes outside of the MEP and carotenoid pathways. This assay enables the rapid screen of new inhibitors of enzymes preceding the synthesis of phytoene, though there are some limitations related to the non-specific effect of some inhibitors on this assay.

Roots of the invasive species Carduus nutans L. and C. acanthoides L. produce large amounts of aplotaxene, a possible allelochemical.

The invasive thistle Carduus nutans has been reported to be allelopathic, yet no allelochemicals have been identified from the species. In a search for allelochemicals from C. nutans and the closely related invasive species C. acanthoides, bioassay-guided fractionation of roots and leaves of each species were conducted. Only dichloromethane extracts of the roots of both species contained a phytotoxin (aplotaxene, (Z,Z,Z)-heptadeca-1,8,11,14-tetraene) with sufficient total activity to potentially act as an allelochemical. Aplotaxene made up 0.44 % of the weight of greenhouse-grown C. acanthoides roots (ca. 20 mM in the plant) and was not found in leaves of either species. It inhibited growth of lettuce 50 % (I 50) in soil at a concentration of ca. 0.5 mg g(-1) of dry soil (ca. 6.5 mM in soil moisture). These values gave a total activity in soil value (molar concentration in the plant divided by the molarity required for 50 % growth inhibition in soil = 3.08) similar to those of some established allelochemicals. The aplotaxene I 50 for duckweed (Lemna paucicostata) in nutrient solution was less than 0.333 mM, and the compound caused cellular leakage of cucumber cotyledon discs in darkness and light at similar concentrations. Soil in which C. acanthoides had grown contained aplotaxene at a lower concentration than necessary for biological activity in our short-term soil bioassays, but these levels might have activity over longer periods of time and might be an underestimate of concentrations in undisturbed and/or rhizosphere soil.

Differential responses between mature and young leaves of sunflower plants to oxidative stress caused by water deficit / Diferentes respostas entre folhas adultas e jovens de plantas de girassol ao estresse oxidativo causado pelo déficit hídrico

The effects of water stress and rehydration on leaf gas exchange characteristics along with changes in lipid peroxidation and pirogalol peroxidase (PG-POD) were studied in mature and in young leaves of sunflower (Helianthus annuus L.), which were grown in a greenhouse. Water stress reduced photosynthesis (Pn), stomatal conductance (g s), and transpiration (E) in both young and mature leaves. However, the amplitude of the reduction was dependent on leaf age. The intercellular CO2 concentration (Ci) was increased in mature leaves but it was not altered in young leaves. Instantaneous water use efficiency (WUE) in mature stressed leaves was reduced when compared to control leaves while in young stressed leaves it was maintained to the same level as the control. After 24h of rehydration, most of the parameters related to gas exchange recovered to the same level as the unstressed plants except gs and E in mature leaves. Water stress did not activated PG-POD independently of leaf age. However, after rehydration the enzyme activity was increased in mature leaves and remained to the same as the control in young leaves. Malondialdehyde (MDA) content was increased by water stress in both mature and young leaves. The results suggest that young leaves are more susceptible to water stress in terms of gas exchange characteristics than mature leaves although both went through oxidative estresse.

Os efeitos do estresse hídrico e da reidratação nas trocas gasosas juntamente com alterações na lipoperoxidação e atividade da pirogalol peroxidase (PG-POD) foram estudados em folhas adultas e jovens de plantas de girassol (Helianthus annuus L.) cultivadas em casa de vegetação. O estresse hídrico reduziu a fotossíntese (P N), a condutância estomática (g s) e a transpiração (E) nas folhas adultas e jovens. No entanto, a amplitude da redução foi dependente da idade da folha. A concentração intercelular de CO2 (Ci) aumentou nas folhas adultas, mas não apresentou alteração nas folhas jovens sob condições de estresse hídrico. A eficiência instantânea do uso da água (WUE) nas folhas adultas e estressadas foi reduzida em comparação com o controle, enquanto que, nas folhas jovens e estressadas, não foi alterada. Após 24h de reidratação, as folhas apresentaram valores semelhantes aos dos controles em todos os parâmetros relacionados com as trocas gasosas, exceto gs e E nas folhas adultas. O estresse hídrico não ativou a PG-POD, independente da idade da folha, e após a reidratação a atividade da PG-POD foi aumentada apenas nas folhas adultas. O estresse hídrico aumentou o teor de malondialdeído (MDA) nas folhas adultas e jovens. Os resultados sugerem que as folhas jovens são mais susceptívies ao déficit hídrico em termos de trocas gasosas que as folhas adultas, embora ambas tenham sido expostas ao estresse oxidativo.

Ultraviolet-B and water stress effects on growth, gas exchange and oxidative stress in sunflower plants.

The effects and interaction of drought and UV-B radiation were studied in sunflower plants (Helianthus annuus L. var. Catissol-01), growing in a greenhouse under natural photoperiod conditions. The plants received approximately 1.7 W m(-2) (controls) or 8.6 W m(-2) (+UV-B) of UV-B radiation for 7 h per day. The UV-B and water stress treatments started 18 days after sowing. After a period of 12 days of stress, half of the water-stressed plants (including both UV-B irradiated or non-irradiated) were rehydrated. Both drought and UV-B radiation treatments resulted in lower shoot dry matter per plant, but there was no significant interaction between the two treatments. Water stress and UV-B radiation reduced photosynthesis, stomatal conductance and transpiration. However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercelluar CO(2) concentration was initially reduced in all treatments compared to control plants but it increased with time. Photosynthetic pigments were not affected by UV-B radiation. Water stress reduced photosynthetic pigments only under high UV-B radiation. The decrease was more accentuated for chlorophyll a than for chlorophyll b. As a measure for the maximum efficiency of photosystem II in darkness F (v)/F (m) was used, which was not affected by drought stress but initially reduced by UV-B radiation. Independent of water supply, UV-B radiation increased the activity of pirogalol peroxidase and did not increase the level of malondialdehyde. On the other hand, water stress did not alter the activity of pirogalol peroxidase and caused membrane damage as assessed by lipid peroxidation. The application of UV-B radiation together with drought seemed to have a protective effect by lowering the intensity of lipid peroxidation caused by water stress. The content of proline was not affected by UV-B radiation but was increased by water stress under both low and high UV-B radiation. After 24 h of rehydration, most of the parameters analyzed recovered to the same level as the unstressed plants.