ice blast disease is an important threat to global food security 1 . The disease starts when asexual spores of Magnaporthe oryzae, called conidia, land on the hydrophobic surface of a rice leaf inducing differentiation of an infection cell called an appressorium 1-3 . The appressorium develops turgor of up to 8.0 MPa due to glycerol accumulation, which generates osmotic pressure 4 . Glycerol is maintained in the appressorium by melanin in the cell wall, which reduces its porosity 4,5 . Development of the appressorium is tightly linked to the cell cycle, autophagy [6][7][8] and metabolic checkpoint control mediated by TOR kinase and the cAMP-dependent protein kinase A (PKA) pathway [9][10][11] . Appressorium turgor is monitored by a sensor kinase, Sln1, and once a threshold is reached 12 , septin GTPases in the appressorium pore form a hetero-oligomeric complex that scaffolds cortical F-actin at the base of the appressorium 13,14 . This leads to force generation to pierce the cuticle with a rigid penetration hypha. Once inside the leaf, invasive hyphae colonize the first epidermal cell before seeking out plasmodesmata-rich pit fields through which the fungus invades neighbouring cells 15 . M. oryzae actively suppresses plant immunity using fungal effector proteins delivered into plant cells 16 . After five days, disease lesions appear from which the fungus sporulates to colonize neighbouring plants.Formation of an appressorium by M. oryzae requires a conserved pathogenicity mitogen-activated protein kinase (MAPK), called Pmk1 (ref. 17 ). Pmk1 mutants cannot form appressoria or cause plant infection, even when plants are wounded 17 . Instead, Δpmk1 mutants produce undifferentiated germlings that undergo several rounds of mitosis and septation 17,18 . Pmk1 is also responsible for lipid and glycogen mobilization to the appressorium, autophagy in the conidium 4,8,19,20 and invasive cell-to-cell movement 15 . A set of pl surface sensors 21 that trigger cAMP-PKA signalling are required for Pmk1 activation 17 , and a TOR-dependent nutrient sensing pathway is necessary for appressorium formation, acting upstream, or perhaps independently, of Pmk1 (refs. [9][10][11] ). The mechanism by which Pmk1 exerts such an important role in plant infection has remained largely unknown and only one transcriptional regulator, Mst12, which may act downstream of Pmk1, has been characterized in detail. Mst12 mutants form appressoria normally but are non-functional and cannot cause disease 22 .In this study we set out to identify the mechanism by which major transcriptional changes are regulated during appressorium development by M. oryzae. We identified major temporal changes in gene expression in response to an appressorium-inductive hydrophobic

Avocado sunblotch viroid (ASBVd) is an economically important pathogen that reduces the yield and quality standards of infected avocado trees. There are no reports on the effects of the viroid in the postharvest quality of avocado fruits. The present study has focused on three phenotypic classes: asymptomatic fruits harvested from vigorous trees (AF-V), asymptomatic fruits harvested from trees of regular vigor (AF-R) and symptomatic fruits harvested from trees expressing the disease (SF-S). The water loss was similar in the three fruit classes. The abnormal firmness condition, skin color and size reduction occurred only in SF-S fruits, which did not ripe uniformly due to reduced CO 2 and ethylene production. The proximal analyses showed no significant differences in the variables analyzed, except for the lipid content and dry matter, which was lower in SF-S and AF-R fruits. ASBVd affects physiology and postharvest quality of symptomatic avocado fruits. In contrast, the ripening process of AF-V and AF-R fruits was normal and their physical characteristics and nutrient input were not altered, therefore, these fruits were classified as Supreme Quality, Extra Size (221-265 g) and Premium (172-210 g) according to the NMX-FF-016-SCFI-2006 standards.

Two groups of viruses cause the citrus disease complex known as leprosis: the cytoplasmic type, of the genera Cilevirus and Higrevirus, and the nuclear type, of the genus Dichorhavirus. It has been shown that the cilevirus Citrus leprosis virus C (CiLV-C) is transmitted by Brevipalpus yothersi. Within the genus Dichorhavirus, CiLV-N is a recently described and distinct species present in Brazil and transmitted by B. phoenicis sensu stricto, whereas the species found in Mexico and Colombia are strains of Orchid fleck virus (OFV-citrus), suspected to be vectored by B. californicus. A study was conducted to determine whether B. californicus and B. yothersi can acquire and inoculate Mexican isolates of CiLV-C and OFV-citrus to sweet and acid citrus species (sweet orange, mandarin, grapefruit, sour orange, Persian lime and Mexican lime) in experiments set up in areas in Mexico with prevalence of the respective viruses. Brevipalpus californicus acquired OFV-citrus and transmitted it to all the citrus cultivars included in the experiment, while B. yothersi acquired CiLV-C and transmitted it only to sweet citrus cultivars (sweet orange, mandarin, and grapefruit). Both mite species were able to become established and reproduce in the experimental plants for nearly a year. This study represents the first experimental evidence of OFV-citrus transmission by B. californicus, as well as evidence that B. yothersi cannot transmit this virus.

La monoliasis del cacao (Moniliophthora roreri) es la principal limitante parasítica de la producción de cacao (Theobroma cacao) en México. Una alternativa sostenible para el control de la enfermedad es el uso del hongo Trichoderma. El objetivo del presente estudio fue seleccionar aislamientos nativos de Trichoderma con las mejores características antagónicas y fisiológicas in vitro, para el control de M. roreri. Para ello, se caracterizaron 50 aislamientos de Trichoderma, obtenidos del agroecosistema cacao. El crecimiento micelial y la producción de conidios a 25, 30 y 35 °C se consideraron variables fisiológicas. El micoparasitismo, antibiosis y antagonismo potencial fueron las variables antagónicas. Se encontraron diferencias significativas (P = 0.0001) en todas las variables evaluadas. El intervalo de temperatura óptima para el crecimiento micelial y producción de conidios fue de 25 a 30 °C. El micoparasitismo varió de 0 a 100 % y solo los aislamientos de seis especies mostraron esta característica. La antibiosis osciló entre 6.8 y 55.5 %, y el antagonismo potencial varió de 3.4 a 69 %. Trichoderma virens (TTC017) y T. harzianum (TTC090, TTC039, TTC073) mostraron el mejor biocontrol potencial in vitro, por lo que son cepas prometedoras para futuras investigaciones sobre control biológico de la moniliasis del cacao.