Plants and plant pathogens are subject to continuous co-evolutionary pressure for dominance, and the outcomes of these interactions can substantially impact agriculture and food security1–3. In virus– plant interactions, one of the major mechanisms for plant antiviral immunity relies on RNA silencing, which is often suppressed by co-evolving virus suppressors, thus enhancing viral pathogenicity in susceptible hosts1. In addition, plants use the nucleotide-binding and leucine-rich repeat (NB-LRR) domain-containing resistance proteins, which recognize viral effectors to activate effector-triggered immunity in a defence mechanism similar to that employed in non-viral infections2,3. Unlike most eukaryotic organisms, plants are not known to activate mechanisms of host global translation suppression to fight viruses1,2. Here we demonstrate in Arabidopsis that the constitutive activation of NIK1, a leucine-rich repeat receptor-like kinase (LRR-RLK) identified as a virulence target of the begomovirus nuclear shuttle protein (NSP)4–6, leads to global translation suppression and translocation of the downstream component RPL10 to the nucleus, where it interacts with a newly identified MYB-like protein, L10-INTERACTING MYB DOMAIN-CONTAINING PROTEIN (LIMYB), to downregulate translational machinery genes fully. LIMYB overexpression represses ribosomal protein genes at the transcriptional level, resulting in protein synthesis inhibition, decreased viral messenger RNA association with polysome fractions and enhanced tolerance to begomovirus. By contrast, the loss of LIMYB function releases the repression of translation-related genes and increases susceptibility to virus infection. Therefore, LIMYB links immune receptor LRR-RLK activation to global translation suppression as an antiviral immunity strategy in plants.

The NSP-interacting kinase, NIK, belongs to the five leucine-rich repeats-containing receptor-like serine/threonine kinase subfamily that includes members involved in plant development and defence. NIK was first identified by its capacity to interact with the geminivirus nuclear shuttle protein (NSP) and has been strongly associated with plant defence against geminivirus. Recent studies corroborate its function in transducing a defence signal against virus infection and describe components of the NIK-mediated antiviral signalling pathway. This mini-review describes the role of NIK as a transducer of a novel layer of plant innate defence, presents new data on NIK function, and discusses its possible involvement in plant development.

Fitness cost is usually associated with insecticide resistance and may be mitigated by increased energy accumulation and mobilization. Preliminary evidence in the maize weevil (Coleoptera: Curculionidae) suggested possible involvement of amylases in such phenomenon. Therefore, alpha-amylases were purified from an insecticide-susceptible and two insecticide-resistant strains (one with fitness cost [resistant cost strain], and the other without it [resistant no-cost strain]). The main alpha-amylase of each strain was purified by glycogen precipitation and ion-exchange chromatography (>or=70-fold purification,

The nutritional status, juice quality and sugar production of sugarcane varieties RB867515 and RB92579 were evaluated in the cane-plant cycle, as a function of magnesium doses applied at the bottom of the planting furrow. The study, installed in soil with a Mg content equal to 0.61 cmolc dm-3, was conducted in an experimental design in randomized blocks with four replications. The study was a 2 x 5 factorial: two sugarcane varieties: RB867515 and RB92579, and five doses of magnesium: zero, 60, 120, 180 and 240 kg per hectare, using magnesium oxide as a source of Mg. commercial magnesium. The plots consisted of seven furrows of five meters in length with 1.0 meter spacing. All plots received phosphorus and potassium fertilization at a dose of 100 kg of phosphorus and 150 kg of potassium per hectare, with no nitrogen fertilization. In the maximum growth phase of sugarcane, the nutritional status of sugarcane was evaluated. About a year after planting, when the cane was mature, the cane plant was harvested to assess the quality of the juice and the sugar production of the varieties. There was no effect of magnesium fertilization on any of the analyzed variables. Regarding the nutrient content in leaf +3, nutritional deficiency was found only for potassium, copper and manganese. The RB92579 had an average productivity of industrializable stalks and sugars, respectively of 96.0 and 13.7 tons per hectare, surpassing the RB867515 by about 10%. The results of this study confirm reports by other researchers who mention that Mg contents of the order of 0.50 cmolc dm-3 are sufficient for adequate nutrition of sugarcane.

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