Abstract Pineapple (Ananas comosus var. comosus) fusariosis is an economically important fungal disease affecting the plant and its fruit. A rapid and reliable diagnosis is the base of integrated disease management practices. Fusariosis has resulted in quarantines for pineapple products in Central America, Africa and Asia. Difficulties diagnosing and correctly identifying the fungus Fusarium guttiforme, agent of the pineapple fusariosis, have led to the search for new methodologies, and for this we developed a new reliable molecular method to detect it. For diagnostic purposes, real-time PCR of elongation factor gene 1-α (ef1) was used to rapidly, specifically and sensitively diagnose F. guttiforme. A pathogenicity test was conducted with slips of the pineapple cultivar Pérola, a multiplex PCR was run, and the results compared with those obtained with real-time PCR. The real-time PCR assay with its specific primer set could readity distinguish F. guttiforme from other Fusarium species known to occur on pineapple. The real-time PCR test had 95% sensitivity and 100% specificity with a significance level p<0.0001. For field samples the test had 100% sensitivity and specificity. Thus, this new test is fit for use in serial analyses of pineapples, and may have application in the evaluation of propagation materials and making quarantine decisions. The ability to rapidly and specifically detect F. guttiforme in plant samples will facilitate monitoring of the pathogen and improve disease management.

As viroses são problemas importantes para a agricultura moderna e o seu controle representa um desafio para o manejo de áreas cultivadas. As principais estratégias de resistência a vírus se baseiam em mecanismos naturais ou em engenharia genética. Recentemente, a maior compreensão dos mecanismos moleculares envolvidos na função de genes de resistência da planta facilitou o desenvolvimento de novas estratégias antivirais. Plantas modificadas geneticamente, em particular aquelas expressando a via de silenciamento de RNA, são alvo de interesse crescente e representam a possibilidade de estratégias futuras mais efetivas. Neste trabalho são discutidos diferentes aspectos relacionados à resistência a viroses em plantas. Adicionalmente, a perspectiva de aplicação biotecnológica das diferentes vias de resistência é apresentada.

Virus diseases are significant threats to modern agriculture and their control remains a challenge to the management of cultivation. The main virus resistance strategies are based on either natural resistance or engineered virus-resistant plants. Recent progress in understanding the molecular mechanisms underlying the roles of resistance genes has promoted the development of new anti-virus strategies. Engineered plants, in particular plants expressing RNA-silencing nucleotides, are becoming increasingly important and are likely to provide more effective strategies in future. A general discussion on the biotechnology of plant responses to virus infection is followed by recent advances in engineered plant resistance.