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Trabajo presentado en el XX Congreso de la Sociedad Española de Fitopatología celebrado en Valencia del 24 al 26 de octubre de 2022., Potato spindle tuber viroid (PSTVd) is a plant pathogen naturally infecting economically important crops such tomato (Solanum lycopersicum). Here, we aimed to engineer tomato plants highly resistant to PSTVd and developed several S. lycopersicum lines expressing an artificial microRNA (amiRNA) against PSTVd (amiR-PSTVd). Infectivity assays revealed that amiR-PSTVd-expressing lines were not resistant but rather hypersusceptible to the viroid. A combination of phenotypic, molecular and metabolic analyses of amiRNA-expressing lines non-inoculated with the viroid revealed that amiR-PSTVd was accidentally silencing the tomat STEROL GLYCOSYLTRANSFERASE 1 (SlSGT1) gene, which caused late developmental and reproductive defects such as leaf epinasty, dwarfism or reduced fruit size. Importantly, two independent transgenic tomato lines each expressing a different amiRNA specifically designed to target SlSGT1 were also hypersusceptible to PSTVd, thus confirming that downregulation of SlSGT1 was responsible for the viroid hypersusceptibility phenotype. Our results highlight the role of SGTs in proper plant development and indicate that the unbalance of sterol glycosylation levels favors viroid infection most likely by facilitating viroid movement.

Trabajo presentado en el XVI Meeting of Plant Molecular Biology celebrado en Sevilla entre el 14 y el 16 de septiembre de 2022., Potato spindle tuber viroid (PSTVd) is a plant pathogen naturally infecting economically important crops such as tomato (Solanum lycopersicum)1. Here we aimed to engineer tomato plants highly resistant to PSTVd and developed several S. lycopersicum lines expressing an artificial microRNA (amiRNA) against PSTVd (amiR-PSTVd), which was previously shown to interfere with PSTVd infection in Nicotiana benthamiana². Surprisingly, infectivity assays revealed that amiR-PSTVdexpressing lines were not resistant but rather hypersusceptible to the viroid. A combination of phenotypic, molecular and metabolic analyses of amiRNA-expressing lines non-inoculated with the viroid revealed that amiR-PSTVd was accidentally silencing the tomato STEROL GLYCOSYLTRANSFERASE 1 (SlSGT1) gene, which caused late developmental and reproductive defects such as leaf epinasty, dwarfism or reduced fruit size. Importantly, two independent transgenic tomato lines each expressing a different amiRNA specifically designed to target SlSGT1 were also hypersusceptible to PSTVd, thus confirming that downregulation of SlSGT1 was responsible for the viroid hypersusceptibility phenotype. Our results highlight the role of SGTs in proper plant development and indicate that the unbalance of sterol glycosylation levels favors viroid infection most likely by facilitating viroid movement., This work was supported by grants from Ministerio de Ciencia e Innovación (MCIN, Spain), Agencia Estatal de Investigación (AEI, Spain) and Fondo Europeo de Desarrollo Regional (FEDER, European Union) (RTI2018 095118-A-100 and RYC-2017-21648 to A.C, PRE2019-088439 to AEC, PIE2020-116765RB-I00 to P.L. and PID2020-114691RB-I00 to J.-A.D, AGL2017-88842-R to AF and TA, and Severo Ochoa Programme for Centres of Excellence in R&D CEX2019-000902-S), Generalitat Valenciana (PROMETEU/2021/056 to P.L.), Generalitat de Catalunya (2017SGR710 and CERCA Programme)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000902-S)

To study the first impact of the COVID-19 crisis on the results obtained by students belonging to the School of Agricultural Engineering and Environment at the Universitat Politècnica de València (Spain), the average of the marks corresponding to three academic years (2016–2019) was compared to those obtained in 2019–2020 for a total of four bachelor’s degrees and two semesters. Our results suggest a positive effect on the marks obtained during the activation of emergency remote teaching during the spring semester of 2019–2020 in three out of the four degrees, with these differences being significant for the whole study. Moreover, just at the end of that period, instructors and students were surveyed regarding teaching methodologies, evaluation modalities, and difficulties found throughout the process of adapting to distance teaching. Our results allow us to sensibly think about that exceptional situation in order to propose a set of counterweighting measures which could improve the implementation of distance learning in engineering colleges.

[ES] Los consumidores son conscientes del peligro derivado del uso de antioxidantes y antimicrobianos sintéticos en la industria agroalimentaria, demandando alternativas más seguras y ecológicas. En este estudio, se ha determinado la actividad antioxidante de aceites esenciales comerciales mediante el método DPPH y su efecto antimicrobiano frente a la bacteria Pseudomonas syringae y el hongo fitopatógeno Fusarium oxysporum a través del empleo del método estandarizado de disco. Los aceites esenciales de clavo, ajedrea, canela y orégano, así como carvacrol, mostraron la máxima actividad antioxidante, comparable a antioxidantes establecidos. El aceite esencial de gaulteria fue el más potente inhibidor del crecimiento de P. syringae en las dosis más altas (20 y 10 µL) ensayadas. El aceite esencial de orégano, así como su componente principal carvacrol, detuvieron el crecimiento de la bacteria incluso a la dosis más baja ensayada (1 µL). Los aceites esenciales de canela, orégano y menta inhibieron el desarrollo de F. oxysporum en todas las dosis (20, 10 y 5 µL) aplicadas. En general, la mayoría de aceites esenciales mostraron más actividad antifúngica que antibacteriana y antioxidante. [EN] Consumers are aware of the dangers arising from the use of synthetic antioxidants and antimicrobials in the agrifood industry, demanding safer and "greener" alternatives. In this study, the antioxidant activity of commercial essential oils through DPPH method, their antimicrobial effects against the bacterium Pseudomonas syringae and the phytopathogenic fungus Fusarium oxysporum by means of the standardized disk method were determined. Clove along with winter savory, cinnamon and oregano essential oils as well as carvacrol showed the highest antioxidant activity comparable to reference standards. Wintergreen essential oil was the most potent inhibitor against P. syringae growth at the highest doses (20 and 10 µL). Oregano essential oil and its main component carvacrol were able to stop the bacterium growth even at the lowest treatment (1 µL). Cinnamon, oregano and peppermint essential oils inhibited F. oxysporum development at all doses (20, 10 and 5 µL) assayed. In general, most of the essential oils displayed more antifungal than antibacterial and antioxidant activities.

Additional file 3: Figure S3. Twi1 enzyme activity towards umbelliferone, 2,4-DHBA and sculetin.