COVID-19 in the International Year of Plant Health

<p>Pests, in their broad sense, have played an important part in the history of humankind. We could say that humans, crops and pests have walked together through life. Codices, glyphs, paintings and countless ancient documents, including the Bible and the Koran, bear witness to this. Humanity has been attacked by its own diseases, but also by those that limit them from obtaining food and deteriorate the environment. COVID-19, which is now troubling us and was declared a pandemic by the World Health Organization in March of 2020, became a part of the list of experiences we have suffered in the past, with pests or epidemics that caused millions of deaths by diseases or famines. It is paradoxical that this health contingency occurs when the United Nations General Assembly, on December 20th, 2018, in its resolution A/RES/73/252 decides to declare 2020 the International Year of Plant Health in order to “highlight the importance of plant health to improve food security, protect the environment and biodiversity and boost economic development” according to the pronouncement by the FAO. For the first time, in an era with great technological and scientific breakthroughs, humanity was aware of its vulnerability against the inevitable evolution of life forms in the face of dilemmas global impact caused by human beings. Thus, the pest or parasite makes its own declaration of existential preeminence through SARS-CoV-2 to remind us that the health of humans or plants is the essence of life and its continuity. But perhaps absolute health is not enough. It is necessary to find a balance in a world overwhelmed by giving so much in return for almost nothing to everyone living on it. If the sensor of our anthropocentric intervention of the world is climate change, then biological chaos is a masterpiece. The reemergence of pests and diseases considered eradicated, or those of zoonotic origin that had never accompanied our existence is a surreal dystopia that we will never be able to deny again.</p>

First report of Alternaria alternata causing the golden spot in xoconostle (Opuntia matudae) in Hidalgo, México

The species<em> Opuntia ficus-indica</em> is affected by pests and diseases, one of the most important of these being golden spot. The latter has been reported in various countries, including Mexico. Symptoms similar to those of golden spot in <em>O. ficus-indica</em> have been observed in the xoconostle crop (<em>Opuntia matudae</em> Scheinvar, cv. Rosa). The objective of this study was to isolate and identify the causative agent that causes the symptoms, which resembled those of the disease described as golden spot in <em>O. ficus-indica</em>. Simple random sampling in the field (10 plots) was carried out on xoconostle plants that presented the described symptoms. Slices of diseased plant tissue were cut and placed in Petri plates with PDA medium. Compliance with Koch’s postulates showed that the isolated (one aislated) of <em>Alternaria</em> sp. obtained from the field samples colonized the cladodes after inoculations in the greenhouse. Through taxonomic keys, <em>Alternaria</em> sp. was identified as the causative microorganism. Molecular characterization of the isolated <em>Alternaria</em> sp. was identified as <em>Alternaria</em> <em>alternata</em>. This is the first report worldwide of <em>Alternaria alternata</em> as the causal agent of golden spot in a xoconostle crop.

Characterization and fungicides sensitivity of Phytophthora cinnamomi isolates causing avocado root rot in Zitácuaro, Michoacán

<em>Phytophthora cinnamomi</em> is the pathogen most frequently associated with avocado root rot. In Zitácuaro, Michoacán, production has increased by 19.8%; however, there are no studies of root rot in this area. The objective of the study was to characterize the isolates obtained from avocado roots and assess the sensitivity to fungicides. Samples from 5 avocado orchards were collected, sampling 5 trees per orchard (a total of 25 samples). The samples isolated were characterized morphological and molecularly. Mating type was analyzed using reference isolates of<em> P. cinnamomi</em> A1 (isolate from camelia) and A2 (isolate from avocado). To confirm the pathogenicity, tests were performed on avocado fruits with the isolates. The sensitivity of 15 isolates to potassium phosphite and to metalaxyl-M at different concentrations was evaluated<em> in vitro</em>. In a subgroup of six isolates, it was evaluated whether there was a relationship between growth rate and potassium phosphite sensitivity. Fifteen isolates were obtained with coenocytic coraloid mycelium, chlamydospores, sporangia without papilla, ovoid to ellipsoid, with internal proliferation, heterothallic with mating type A2, with amphigynous antheridia and plerotic oospores, characteristics consistent with <em>P. cinnamomi</em>. The inoculated isolates were pathogenic on avocado fruits. The isolates were more sensitive to potassium phosphite than to metalaxyl-M, with mean EC50 values of 24.62 and 0.215 ?g mL-1 of i.a., respectively. No relationship was observed between growth rate and potassium phosphite sensitivity. It is necessary to obtain a greater number of<em> P. cinnamomi</em> isolates for virulence studies.

Characterization and pathogenicity of a Pythium aphanidermatum isolate causing ‘damping off’ in pepper seedlings

<p>The production of the pepper seedling (<em>Capsicum annuum</em>) is affected by the fungal complex that causes the ‘damping-off’, in which some species of the oomycete <em>Pythium</em> spp., stand out. The objective of the present study was to identify the causal agent of the death of pepper plants and evaluate its pathogenicity in pepper seeds and seedlings. A fast and aggressive growing oomycete was isolate from pepper plants, morphologically identified as P. aphanidermatum based on its sexual and asexual reproduction structures and, by molecular techniques. This isolate had a high degree of<em> in vitro</em> pathogenicity in pre-emergence and post-emergence in chile, showing 100% mortality. In addition, it presented a high rate of mycelial growth in different culture media (V8-Agar, Corn Agar, Corn Potato Agar, Potato Dextrose Agar, Czapek &amp; Oat Agar), being in V8-Agar medium the only medium where it developed reproduction structures sexual and asexual. The isolation presented a mycelial growth rate of 58.3 ± 0.3 mm / day at 26 ± 2 °C in PDA medium. Due to its rapid growth and its high degree of pathogenicity <em>in vitro</em>, it is an unusual and aggressive isolate for pepper seedlings.</p>

Aqueous extracts from Acalypha gaumeri and Bonellia flammea for leaf blight control in chrysanthemum (Chrysanthemum morifolium)

The chrysanthemum is the second most important cut flower in the world, however, its quality and commercial value is affected by the leaf blight produced by <em>Alternaria </em>spp. The objective of this work was to evaluate the causal agent of leaf blight in Chrysanthemum, and its control with aqueous extracts of <em>Acalypha gaumeri </em>and <em>Bonellia flammea</em>. The fungus was collected and identified from leaves and stems of chrysanthemum plants. Subsequently, molecular identification and pathogenicity tests were performed on chrysanthemum plants. In the field, treatments were evaluated with weekly applications of: T1: <em>B. flammea </em>bark extract, T2: <em>A. gaumeri </em>root extract, T3: negative control (water) and T4: Captan® fungicide. Prior to the application of the treatments, plants were inoculated with the isolated fungus (2.5 × 106 spores mL-1) and severity was evaluated. <em>Alternaria chrysanthemi </em>was identified as the causal agent. Based on the severity percentage, the lowest averages of the area under the disease progress curve, the lowest rates of apparent infection, the lowest intensity of the disease and the greater effectiveness in controlling the disease were observed for T2 (165, 0.017, 8 and 67%, respectively) followed by T1 (186, 0.022, 13 y 50 %, respectively) and T4 (179, 0.023, 14 y 45%, respectively), observing a significantly different than negative control T3 (369, 0.025, 25 and 0%, respectively). Plant extracts have potential to be used as an alternative in the management of <em>Alternaria </em>leaf blight in chrysanthemum.

Response of tomato (Solanum lycopersicum) varieties to Clavibacter michiganensis subsp. michiganensis infection

<p><em>Clavibacter michiganensis</em> subsp. <em>michiganensis</em> causes bacterial wilt and canker disease of tomato. The objectives of this research were i) to characterize and identify the most aggressive Cmm in Chignahuapan, Puebla, ii) to evaluate the tolerance in two phenological stages of 10 tomato varieties to infection by CP_Cmm1 in the greenhouse and the <em>in vitro</em> sensitivity of the bacteria to bactericides. 12 Cmm isolates were collected from tomato plants and a strain (CP_Cmm-1) with greater aggressiveness was selected according to the time of manifestation of symptoms in plants of var. Reserva. Afterward, the strain was inoculated by cutting with scissors embedded in a suspension with 3 x 108 UFC mL-1 in two phenological stages (at five and 10 true leaves). Symptoms were evaluated for 30 days after inoculation. Additionally, the sensitivity of CP_Cmm-1 to eight commercial bactericides <em>in vitro</em> was evaluated. The results showed that the CP_Cmm-1 strain was identified with 97% similarity with the API20 E system, positive with DAS-ELISA, and by PCR it showed 96.6% identity with <em>Clavibacter michiganensis</em> subsp. <em>michiganensis</em>. The Saher variety showed greater tolerance to infection (* = p?0.05) both in the stage of five and 10 leaves; the varieties Sv4401, Nápoles, and Súper óptimo showed greater susceptibility in the five-leaf stage. The Sv4401 variety was highly susceptible in both stages. Neither variety was resistant to infection by CP_Cmm-1. The use of the Sahel variety and kasugamycin could reduce the damage of this bacteria.</p>

Fusarium sp., causal agent of vascular wilt in citrus and its sensitivity to fungicides

<p>Citrus wilt is a disease of recent appearance in the northern area of Veracruz that causes economic losses to producers in the region. The present work aimed to identify the causative agent of this disease and evaluate different fungicides to determine its<em> in vitro</em> sensitivity. A fungus was consistently isolated in plants with wilt symptoms; it was morphologically identified indifferent culture media and molecularly identified by PCR using the EF1-728F/EF1-986R primers. The fungus was inoculated in three varieties of citrus under greenhouse conditions. The sensitivity test was carried out with the fungicides chlorothalonil, benomyl thiabendazole, prochloraz, and a biological agent (<em>Bacillus subtilis</em>) at different concentrations, plus a negative control. <em>Fusarium</em> sp. (Accession No. MW438335) was morphologically and molecularly identified as the causal agent of vascular wilt in citrus fruits, causing growth retardation, decreased number of roots, wilting of the apical bud, and necrosis in the vascular system of the three varieties inoculated. The most effective fungicides in inhibiting mycelial growth were thiabendazole, prochloraz, and the biological agent <em>Bacillus subtilis</em>.</p>

COVID-19: Threat or ally in the teaching-learning process in phytopathology?

<p>Preventive confinement against COVID-19 changed the teaching-learning process of the Phytopathology course at the Faculty of Agronomy of the UCR. Information and Communications Technologies (ICT) were integrated into a program called ‘Phytopathology 2020, at the distance but together’. Each student received at her home a box of materials, including culture media and a paper microscope, that allowed her to set up and carry out different phytopathological techniques. The result obtained exceeded expectations and previous results in 16 years of teaching experience. The integration of the family into the educational project was surprising, fostering values of mutual commitment in education and prevention of COVID-19.</p>

Challenges of COVID-19 pandemic: The postgraduate case in Sustainable Management of Natural Resources - UIEP

<p>A generalized preventive measure in Mexico against the COVID-19 pandemic was the suspension of in-person non-essential activities, including academic activities. The Universidad Intercultural del Estado de Puebla (Intercultural University of the State of Puebla - UIEP) suspended all classroom course from March 20th, 2019, until the present day. The program of Master of Science in Sustainable Natural Resource Management has remained active in a digital format, facing the following challenges: the speedy implementation of a virtual and distance teaching-learning process; the optimization of computer resources in the face of the digital gap and limited access to these technologies in the region; and an efficient traceability of research processes. COVID-19 displayed the social and digital gap present in the rural areas of Mexico, such as in the case of Sierra Norte de Puebla, in which UIEP is enclaved. However, it also displayed the ability of response and adaptation in the face of the contingency scenario caused by SARS-CoV-2.</p>

Consequences of COVID-19 on my experiment of gene overexpression in beans

<p>My name is Salma Meléndez and I am currently a graduate in Agrogenomic Sciences. In March 2020, when COVID-19 was detected in Mexico, I was in my eighth semester of my undergraduate degree. At that time, he had an experiment of overexpression of a gene in bean roots, in order to explore its function during symbiosis with rhizobial bacteria. Unfortunately, the laboratory and the entire campus canceled their face-to-face activities in order to reduce the risk of contagion. An alternative was to take the experimental plants to my house to give the proper care, however, the situation became difficult as I did not have the space or the required conditions at home. On the other hand, other research centers with which we had collaboration agreements also canceled access, such is the case of the Optical Research Center, where we used the confocal microscope to detect subcellular location of proteins. The closure of institutions allowed me to write theoretical parts of my thesis, however, the experimental phase was definitely affected for at least six months. The experiment with the plants was almost completely lost. In the subsequent months I had the opportunity to re-enter my institution; however, under strict conditions and on staggered days, which made certain measurements that require daily continuity difficult. Currently, the laboratory is not as it used to look, full of colleagues sharing results and difficulties, exchanging advice and even certain materials. I think the pandemic has pushed us to do our work more individually and slowly. Consequently, my degree was delayed and transferred from 2020 to 2021. There are still many challenges to overcome, although activities have not been fully restored, science does not stop and we have found a way to face it, slowly but surely.</p>