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Key message: The miR822 together with of AGO9 protein, modulates monosporic development in Arabidopsis thaliana through the regulation of target genes encoding Cysteine/Histidine-Rich C1 domain proteins, revealing a new role of miRNAs in the control of megaspore formation in flowering plants. In the ovule of flowering plants, the establishment of the haploid generation occurs when a somatic cell differentiates into a megaspore mother cell (MMC) and initiates meiosis. As most flowering plants, Arabidopsis thaliana (Arabidopsis) undergoes a monosporic type of gametogenesis as three meiotically derived cells degenerate, and a single one—the functional megaspore (FM), divides mitotically to form the female gametophyte. The genetic basis and molecular mechanisms that control monosporic gametophyte development remain largely unknown. Here, we show that Arabidopsis plants carrying loss-of-function mutations in the miR822, give rise to extranumerary surviving megaspores that acquire a FM identity and divides without giving rise to differentiated female gametophytes. The overexpression of three miR822 putative target genes encoding cysteine/histidine-rich C1 (DC1) domain proteins, At5g02350, At5g02330 and At2g13900 results in defects equivalent to those found in mutant mir822 plants. The three miR822 targets genes are overexpressed in ago9 mutant ovules, suggesting that miR822 acts through an AGO9-dependent pathway to negatively regulate DC1 domain proteins and restricts the survival of meiotically derived cells to a single megaspore. Our results identify a mechanism mediated by the AGO9-miR822 complex that modulates monosporic female gametogenesis in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]

Amaranth (Amaranthus hypochondriacus L.) is important for its high protein content, as the nutritional value of its grain is due partly to the amount of protein higher than that of other cereals. Grains form in the inflorescences and their architecture depend on whether growth is determinate or indeterminate. By means of scanning electron microscopy and thinning techniques, we obtained images of the morphological changes of the apical meristem during the life cycle of the plant. That tissue remained undifferentiated in the indeterminate phenotype and the inflorescence was spiked, the apical meristem stopped its activity with the formation of each terminal flower, originating a synchronized development. The development of the inflorescence in determinate growth did not present phenological overlap. The branches of this last phenotype were shorter. The seeds of plants with determinate growth were heavier than those of indeterminate growth. The study of apical meristem morphology could be the basis for the analysis of morphogenetic aspects of development, which at the same time are support for the genetic improvement and agronomic management of A. hypochondriacus. [ABSTRACT FROM AUTHOR]

Nopal (Opuntia) is a resource that is discarded after pruning complete cladodes. For this reason, the aim of this study was to investigate the effects of the combined use of organic matter (nopal) and goat manure on changes in soil characteristics and on the growth and yield performance of carrot and tomato plants. Physicochemical analysis of the soil and goat manure was carried out, and germination tests and physical characterization of the plants and the products obtained were performed on tomato and carrot plants after adding the components of the cladodes alone and the cladodes with goat manure. The results showed that the application of the nopal cladode components increased the cation exchange capacity of the soil. The highest germination rate was obtained by the application of liquid nopal, with a 1.7-fold increase in the germination rate of carrot seeds, while that for tomato seeds was only 14%. Similar results were obtained for the germination percentage. An increase in resistance to water stress of approximately 15 days was observed in both tomato and carrot plants. Plant development and production were achieved in tomato, with a 100% increase in carrot plant length and a threefold increase in production. The addition of nopal to the soil improved the soil characteristics and the production yield of carrots and tomatoes. [ABSTRACT FROM AUTHOR]

The Trichoderma harzianum fungus is one of the most widely used biological control agents in agriculture. A new T. harzianum THITR01 strain was isolated and their spores were mutagenized with ethyl methane sulfonate obtaining 174 mutants. M7, M14, M21 and M24 are mutant strains that showed 97.4%-100% antagonist effect against Sclerotium rolfsii, Rhizoctonia solani and Sclerotinia sclerotiorum compared to the wild strain. Under potato dextrose agar (PDA) medium with either NaCl, sorbitol or NaHCO3 there were nonsignificant growth rate differences between the mutants and the wild strain. M14 and M21 mutant strains were inoculated on 'Jalapeño' pepper plants (Capsicum annuum L. var. annuum) with unavailable P promoted a significant increase in root fresh weight (54% and 40%, respectively) and dry weight (28% in both strains), compared to plant inoculation with the wild strain. The M14 strain presented the highest P solubilization ability (13.4 μg g-1) in the substrate and promoted a change on root architecture. There was a higher relative water content (82.9%) in drought stressed plants inoculated with the M24 mutant than in plants that were inoculated with the wild type strain (76.3%), and also higher levels of proline in chili pepper plants inoculated with the M24 mutant (939.5 μg g-1 dry weight) than in plants inoculated with the wild type strain (419.8 μg g-1 dry weight). Therefore, M14, M21 and M24 mutant strains could potentially be used as biocontrol agents and plant protector from abiotic stress. [ABSTRACT FROM AUTHOR]

Introduction: Abiotic stress caused by cold or water-deficit alters many cellular processes that modificate the physiology and biochemistry of plants, which reduces yield of agricultural crops. Gibberellins are phytohormones that can induce growth and development of the plants. There are many genes whose transcription is modified during abiotic stress or by exogenous-gibberellins application; some of them encode for proteins such as LEA that confer protection against low temperature and dehydration, WRKY and FT that take part in the response to abiotic stress, FT that regulates the flowering time, and GA20ox1 that synthesized gibberellins. The understanding of molecular mechanism that regulates the plant responses to abiotic stress or exogenous gibberellins application is essential for Capsicum annuum (pepper) agriculture improvement. To this aim, we have proceeded to study the effect of biotic stress and exogenous phytohormones on C. annuum development, mainly in fruit (chili) production and expression of genes involved in the response to these conditions. Method: The genome of Capsicum annuum contains homologues to the proteins LEA, WRKY, FT and GA20oxy, so we estimate by Real-Time PCR (qPCR) and phenotype analysis, the gene expression and fruits production in plants grown under abiotic stress and after treatment with exogenous gibberellins. Results: The transcripts of CaLea73 and CaWRKY40 increased by cold stress in leaves. While, CaGA20ox1 expression was down-regulated by cold stress, GA3, and hydric stress-GA3 in leaves. This effect was also observed in flower buds of plants grown under water-deficit, treated with gibberellins or hydric stress-GA3; curiously, the transcripts from this gene became slightly abundant in plants grown under water-deficit. CaFT transcription was induced by cold stress and GA3 in leaves and flower buds, respectively; however, transcription of this gene was almost abolished by hydric stress and GA3--hydric stress in both tissues. Cold stress and exogenous phytohormones raised the fruits production. Conclusion: According with these results, we propose that cold treatment induces the plant defense mechanisms through activation of transcription factors like WRKYs and LEA proteins and increases the plant development through induction of signaling pathway of FT. Our study contributes to understanding on molecular mechanisms governing the responses to abiotic stress and the participation of the gibberellins in C. annuum development and to improve the yield of the chili crop. [ABSTRACT FROM AUTHOR]

R1757 --> Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) appeared in Wuhan, China, in December 2019, causing COVID‐19 disease which are cases of SARS‐like atypical pneumonia. As of December 1, 2020, México had reached 1.1 million cases of COVID‐19 and 106 thousand deaths; about 63.6 million cases and 1.47 million deaths are reported worldwide with new cases and increasing mortality every day. To date there is no specific commercial treatment to control the infection. Repurpose drugs targeting the angiotensin‐converting enzyme 2 (ACE2) receptor represents an alternative strategy to block the binding of SARS‐COV‐2 protein S and forestall virus adhesion, internalization and replication in the host cell. Rigid molecular docking was performed using RBD S1 ‐ ACE2 (PDB: 6WV1) interaction site and 1,300 FDA approved and prescripted drugs by the Mexican Public Health System. The results were analyzed by docking score, frequency of the drug at receptor site and the types of interactions in the binding site residues. Within the top‐ranked drugs identified as a potentials inhibitor of RBD S1 ‐ ACE2 interaction we found pitavastatin, cholecalciferol, pargeverine, ipratropium, formoterol and fexofenadine, were the vast majority stands out as they are used as therapies to treat COPD, asthma and virtually any respiratory infection. Our results will serve as the basis for in vitro and in vivo studies to evaluate the potential use of these drugs to generate affordable an easily accessible therapies to treat COVID‐19. [ABSTRACT FROM AUTHOR]