Use of phosphites in postharvest to control anthracnose of yellow passionfruit / Uso de fosfitos em pós-colheita para o controle da antracnose do maracujá-amarelo

Brazil is the largest producer of yellow passionfruit (Passiflora edulis f. flavicarpa) and one of its production problems is the anthracnose (Colletotrichum spp.). The use of fungicides on control of postharvest diseases is a method that protects the fruits during storage. However, precautions must be taken due to fungicide toxicity. The restriction to the use of fungicides in post-harvest led a demand for alternative methods of disease control, and, the phosphite application is one of these methods. Therefore, this work aimed to evaluate the effects of fruit immersion in phosphite on postharvest control of anthracnose. Two tests were developed in vitro to assess the effect on the fungus: phosphite Mg2 (40%P2O5+6%Mg), Zn (40%P2O5+10%Zn), Ca1 (30%P2O5+7%Ca) and K1 (40%P2O5+20%K2O). For the in vivo tests, passionfruit (Gigante Amarelo), were wounded and inoculated (50L; 106conidia mL-1). Two tests were done with: Cu (25%P2O5+5%Cu), 2.5mL L-1; Zn, 2.5mL L-1; K1, 2.5mL L-1; Mg1 (30%P2O5+4%Mg), 3mL L-1; Ca1, 3mL L-1; Ca2 (10%P2O5+6%Ca), 4mL L-1; K2 (40%P2O5+20%K2O), 1.5mL L-1; Mg2 (40%P2O5+6%Mg), 1.5mL L-1; K3 (20%P2O5+20%K2O) 1.75 mL L-1; K4 (30%P2O5+20%K2O), 1.75mL L-1. Other two tests with phosphites Mg2, Ca1, Zn and K1 were with CaCl2 (2%) was developed. In addition, phosphites were tested at 25, 50, 100 and 200% of the dose: K2 (100%; 1.5mL L-1) and Ca1 (100%; 3 mL L-1). The phosphites Mg2, Ca1, K1 and Zn in vitro have reduced mycelial growth and fungus conidia production. The phosphites K1, K2, Ca1 and Zn were the ones that most reduced the size of the anthracnose lesion. There were no differences among treatments, concerning the physico-chemical fruit properties analyzed (% fresh mass loss, total soluble solids, pH and titratable acidity).

O Brasil é o maior produtor mundial de maracujá-amarelo (Passiflora edulis f. flavicarpa) e um dos problemas para sua produção é a antracnose (Colletotrichum spp.). O uso de fungicidas no controle de doenças pós-colheita é um método que protege os frutos durante o armazenamento, mas, precauções adicionais devem ser tomadas quanto à sua toxidade, presença de resíduos e a provável seleção de fungos resistentes. A restrição ao uso de fungicidas na pós-colheita cresceu e levou à procura de alternativas de controle, e, entre tais está à aplicação de fosfitos. Diante disso, este trabalho objetivou avaliar os efeitos da imersão de frutos em soluções de fosfitos no controle da antracnose em pós-colheita. Dois testes in vitro foram feitospara avaliar o efeito de fosfitono fungo: Mg2 (40%P2O5+6%Mg), Zn (40%P2O5+10%Zn), Ca1 (30%P2O5+7%Ca) e K1 (40%P2O5+20%K2O). In vivo, frutos de maracujá (Gigante Amarelo), foram feridos e inoculados (50l; 106conídios mL-1). Dois testes foram feitos com: Cu (25%P2O5+5%Cu), 2,5mL L-1; Zn, 2,5mL L-1; K1, 2,5mL L-1; Mg1 (30%P2O5+4%Mg), 3mL L-1; Ca1, 3mL L-1; Ca2 (10%P2O5+6%Ca), 4mL L-1; K2 (40%P2O5+20%K2O), 1,5mL L-1; Mg2 (40%P2O5+6%Mg), 1,5mL L-1; K3 (20%P2O5+20%K2O), 1,75mL L-1; K4 (30%P2O5+20%K2O), 1,75mL L-1. Outros dois testes com fosfitos foram com CaCl2 (2%) e Mg2, Ca1, Zn e K1. Ainda, dois fosfitos foram testados a 25, 50, 100 e 200% da dose: K2 (100%; 1,5mL L-1) e Ca1 (100%; 3mL L-1). Os fosfitos Mg2, Ca1, K1 e Zn in vitro reduziram o crescimento micelial e a produção de conídios do fungo. Os fosfitos K1, K2, Ca1 e Zn foram que mais reduziram o diâmetro da lesão causada pelo patógeno. Ca1 e K1 com CaCl2 reduziram o tamanho das lesões. Não houve diferenças significativas entre os tratamentos, quanto as características físico-químicas analisadas (% perda de massa fresca, teor de sólidos solúveis totais, pH e acidez titulável) dos frutos.

Establishment of a plant phosphorus utilization and weed control system based on phosphite and its dehydrogenase / 生物工程学报

Nowadays, available phosphorus (P) deficiency in soil and weed resistance to herbicides have emerged as two severe limiting factors for sustainable agriculture. Therefore, it is of urgent needs to improve plant absorption/utilization ability of the soil P, seek phosphate (Pi)-alternative P fertilizers, and develop new forms of weed control systems. Phosphite (Phi), as a P resource of relatively high amount only less than Pi in Earth, can be converted to utilizable Pi uniquely in some bacterial species by oxidization via its specific dehydrogenase (PTDH), but inhibits plant growth and development. This implies that Phi might rather become a suitable P fertilizer for plants if introducing a PTDH detoxifier from bacteria. Herein, we created the transgenic tobaccos harboring a Pseudomonas PTDH gene (PsPtx) amplified from the soil metagenome previously. RT-PCR showed that the exotic PsPtx gene could express similarly in root, stem and leaf tissues of all transgenic lines. PsPtx transgenic tobaccos could utilize Phi by oxidization as the sole Pi supply, and also outperformed wild-type tobacco with a remarkably dominant growth under Phi stress conditions. Moreover, the PsPtx gene was preliminarily evaluated with a notable quality as a potential candidate of the selection marker in plant genetic transformation. Conclusively, PsPtx and its encoded phosphite dehydrogenase might be applicable for developing a dual system of plant phosphorus utilization and weed control using Phi as P fertilizer and herbicide, and provide an effectual solution to some obstacles in the current crop transgenic studies.

Reduction of papaya rot (Phytophthora palmivora) with phosphite and Acibenzolar-S-Methyl in preharvest and postharvest / Redução da podridão do mamão (Phytophthora palmivora) com fosfitos e Acibenzolar-S-Metil em pré e pós-colheita

The papaya fruit rot (Phytophthora palmivora) is responsible for significant losses. To reduce diseases, especially in areas with climate and humidity favorable to pathogens, are adopted chemical methods, which sometimes increase the cost of production and cause severe environmental impacts. Alternatively, there are products, such as, phosphites of potassium and acibenzolar-S-methyl (ASM) that might be efficient on disease control and less aggressive to environment. Phosphites of K and ASM were evaluated in this study on the control effectiveness of papaya fruit rot at different dosages in preharvest and postharvest. The severity and percentage of disease control were evaluated for each treatment. For the pre-harvest treatments (applied six days before harvest), the phosphite of K [240 g L-1 K2O, 340 g L-1 P2O5 and 50 g L-1 (Reforce® + Salicylic Acid)] at 3 or 6 mL L-1significantly reduced disease severity, and, reduced fruit ripening. On postharvest application, ASM reduced disease severity.

A podridão dos frutos do mamoeiro (Phytophthora palmivora) é responsável por perdas significativas e para minimizar a doença, principalmente em locais com clima favorável ao patógeno, medidas de controle químico são adotadas. Porém, estas medidas podem elevar o custo da produção e causar severos impactos ambientais. Alternativamente, existem produtos como os fosfitos de potássio (K) e acibenzolar-S-metil (ASM) que podem ser eficientes no controle de doenças e menos agressivos ao ambiente. Fosfitos de K e ASM foram avaliados neste trabalho quanto à eficácia do controle da podridão de frutos de mamão 'Sunrise Solo' tipo exportação, cultivados no Sul da Bahia, em diferentes doses e formulações comerciais na pré e pós-colheita. Para cada tratamento foi avaliada a severidade da doença e o percentual de controle da doença, sendo também verificada a influência nas características fisioquímicas na fruta. Para os tratamentos pré-colheita, aplicados aos seis dias antes da colheita, o fosfito de K [240 g L-1 K2O, 340 g L-1 P2O5 e 50 g L-1 C7H6O3 (Reforce® + Ácido Salicílico)] a 3 ou 6 mL L-1 reduziu significativamente a doença, e influenciou diretamente no atraso da maturação da fruta. Na pós-colheita, ASM incitou redução na severidade da doença. Todos os tratamentos não alterarão as características fisioquímicas da fruta.

Potassium phosphite: a promising product in the management of diseases caused by Colletotrichum gloeosporioides in coffee plants / Fosfito de potássio: um produto promissor no manejo de doenças causadas por Colletotrichum gloeosporioides em cafeeiro

In recent years coffee productivity has been harmed by diseases caused by Colletotrichum gloeosporioides (Cg), for example, anthracnose, dieback and blister spot. Therefore, it has become necessary to develop alternative measures to control these diseases, since there are no fungicides registered in Brazil for their control. The aims of this work were: to evaluate the effect of potassium phosphite on the germination, fungal appressorium formation and mycelial growth of Cg and to verify this action in the reduction of disease severity of anthracnose in coffee leaves. The treatments used in an in vitro experiment were: potassium phosphite at doses of 1.25, 2.50, 5.0 and 10.0 mL.L-1, Acibenzolar-S-methyl at dose 0.1g.L-1 and Chlorothalonil fungicide at dose 2.0 g.L-1. In an in vivo experiment, beyond the treatments used in the in vitro experiment, we used a control sprayed with water without inoculation and another inoculated with Cg. Potassium phosphite at doses of 5.0 mL.L-1 and 10.0 mL.L-1 and the Chlorotalonil fungicide showed greater inhibition of conidial germination, greater inhibition of appressorium formation and further reduction of mycelial growth of the pathogen. In the in vivo experiment, Potassium phosphite at a dose of 10.0 mL.L-1 provided a greater reduction in disease severity, around 62.5%. This work demonstrated the potential of potassium phosphite in the management of diseases caused by fungi from the Colletotrichum complex in coffee plants.

Nos últimos anos a produtividade de café tem sido prejudicada por doenças causadas por Colletotrichum gloeosporioides (Cg), como por exemplo, antracnose, seca de ponteiros e mancha manteigosa. Portanto torna-se necessário desenvolver medidas alternativas de controle para essas doenças, visto que não existem fungicidas registrados no Brasil para seu controle. O presente trabalho teve como objetivos: avaliar o efeito do fosfito de potássio na germinação, formação de apressórios e no crescimento micelial de Cge verificar a ação do mesmo na redução da severidade da antracnose em folhas de cafeeiro. Os tratamentos utilizados no experimento in vitro foram: fosfito de potássio nas doses de 1,25; 2,50; 5,0 e 10,0 mL.L-1; acibenzolar-S-metil 0,1g.L-1; fungicida clorotalonil 2,0 g.L-1. Já in vivo, além dos tratamentos anteriores, foi utilizada uma testemunha pulverizada com água sem inoculação e outra inoculada com Cg.O fosfito de potássio nas doses de 5,0 mL.L-1 e 10,0 mL.L-1 e o fungicida clorotalonil proporcionaram maior inibição da germinação de conídios, maior inibição da formação de apressórios e maior redução do índice de velocidade de crescimento micelial do patógeno. No experimento in vivo, o fosfito de potássio na dose de 10,0mL.L-1 proporcionou maior redução na severidade da antracnose, em torno de 62,5 %.Este trabalho demonstrou o potencial do fosfito de potássio no manejo de doenças causadas por fungos do complexo Colletotrichum em cafeeiro.

Organophosphorus chemistry, 36[1]reactions of furobenzopyran-6-carboxaldehydes with alkyl phosphites and ylidenetriphenylphosphoranes [Witting reagents]

Dialkyl phosphites [4] and trialkyl phosphites [5] attack the aldehydic carbonyl carbon of 4-methoxy-5-oxo-5H-furo[3,2-g] benzopyran-6-carboxaldehyde [3a] and 4,9-dimethoxy-5-oxo-5H-furo [3,2-g] benzopyran-6- carboxaldehyde [3b] yielding the corresponding alpha-hydroxyphosphonates [7]. Compounds 7 regenerate the starting gamma-pyrone derivatives [3a or 3b] and the appropriate dialkyl phosphites [4] upon thermolysis under reduced pressure. On the other hand, the reaction of 3 with ylidenetriphenylphosphoranes [6] proceeds according to the Wittig mechanism to give the respective ethylenes [E 17]. The reaction of 3b with diethyl cyanomethylphosphonate [18] under Homer-Wittig conditions yields 6-[[alpha-cyano-alpha diethoxyphosphoryl] ethyliden-yl]-4,9-dimethoxy-5-oxo-5H-furo [3,2-g] benzopyran [20]. Structures of the isolated new products were elucidated by compatible, analytical, chemical and spectroscopic measurements