First Report of Anthracnose Caused by Colletotrichum nymphaeae on Strawberry Fruits in Central Argentina.

Strawberry (Fragaria x ananassa) production in Argentina extends to around 1700 hectares. Coronda city, located in Santa Fe province, is an important strawberry producer due to ideal agroecological conditions for culture and a high specialization for production. In November 2021, anthracnose symptoms were observed on strawberries cvs. 'San Andreas' and 'Splendor' in Coronda (31°58'S, 60°55'W), central Argentina. During these years, the incidence of the disease reached 40% of the production. Symptoms included 2-3 mm circular to irregular dark brown spots which enlarged rapidly and became sunken. Under high humidity conditions, concentric rings of pinhead-size salmon-colored acervuli developed on the lesions. The causal agent was isolated by touching acervuli with a sterile needle and monosporic cultures were obtained on PDA after 10 days at 25°C, with a 12-h light period. Colonies were white to gray on the top and orange on the underside, where concentric rings of salmon acervuli were clearly distinguished. The width and length of one hundred conidia were examined in three isolates (CF1, CF2, and CF3), ranging from 3.27 to 5.53 µm (avg.= 4.3 µm), and from 10.37 to 19.52 µm (avg.= 14.27 µm), respectively. The conidia were hyaline, smooth-walled, aseptate, and cylindric-clavate with one end round and one end acute. These morphological characteristics correspond to species belonging to the C. acutatum complex (Damm et al. 2012; Liu et al. 2022). To accurately identify the species, DNA was extracted from isolates, and ß-tubulin (TUB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and histone (HIS3) genes were partially amplified and sequenced (Vieira et al. 2020). TUB2, GAPDH, and HIS3 sequences presented a 100% of identity with species of Colletotrichum nymphaeae. The nucleotide sequences were deposited in GenBank (OR271556-OR271558, TUB2; OR271559-OR271561, GAPDH; and OR271562-OR271564, HIS3). Multilocus phylogenetic analyses performed with reference sequences (Damm et al. 2012) showed that the three isolates clustered with C. nymphaeae, in accordance with BLAST results. To confirm pathogenicity, each isolate was inoculated in eight detached fruits of the cultivar from which it was originally obtained. Two drops of 10 µl of conidial suspension (1x105 conidia per ml) were deposited in non-wounded areas on fruits previously disinfested with 1% sodium hypochlorite solution for 1 min and rinsed twice with sterile distilled water. Drops of sterile water were deposited in eight fruits as control. Pathogenicity tests were repeated twice. Fruits were kept in moist chamber (80+5% relative humidity) at 25°C for ten days. First symptoms appeared 4 days after inoculation. After that, all of the isolates produced symptoms identical to those previously described, whereas the controls remain symptomless. The pathogen was re-isolated from lesions, and identified as C. nymphaeae by morphological characteristics and based on the TUB2 sequences, as previously described. Strawberry anthracnose in Argentina was previously associated with Colletotrichum acutatum, C. gloeosporioides and C. fragariae species based on morphological characteristics (Ramallo et al. 2000; Monaco et al. 2000) but molecular identification was not performed until today. To our knowledge, this is the first report of C. nymphaeae causing anthracnose on strawberry in Argentina. This accurate identification will help to develop more efficient management strategies.

An Update on Phytochemicals and Pharmacological Activities of the Genus Persicaria and Polygonum.

The discovery of new pharmaceutical identities, particularly anti-infective agents, represents an urgent need due to the increase in immunocompromised patients and the ineffectiveness/toxicity of the drugs currently used. The scientific community has recognized in the last decades the importance of the plant kingdom as a huge source of novel molecules which could act against different type of infections or illness. However, the great diversity of plant species makes it difficult to select them with probabilities of success, adding to the fact that existing information is difficult to find, it is atomized or disordered. Persicaria and Polygonum constitute two of the main representatives of the Polygonaceae family, which have been extensively used in traditional medicine worldwide. Important and structurally diverse bioactive compounds have been isolated from these genera of wild plants; among them, sesquiterpenes and flavonoids should be remarked. In this article, we firstly mention all the species reported with pharmacological use and their geographical distribution. Moreover, a number of tables which summarize an update detailing the type of natural product (extract or isolated compound), applied doses, displayed bioassays and the results obtained for the main bioactivities of these genera cited in the literature during the past 40 years. Antimicrobial, antioxidant, analgesic and anti-inflammatory, antinociceptive, anticancer, antiviral, antiparasitic, anti-diabetic, antipyretic, hepatoprotective, diuretic, gastroprotective and neuropharmacological activities were explored and reviewed in this work, concluding that both genera could be the source for upcoming molecules to treat different human diseases.

Bioactivity of Raphanus Species against Agricultural Phytopathogens and its Role in Soil Remediation: A Review.

Phytopathogens and weeds represent around 20-40% of global agricultural productivity losses. Synthetic pesticide products are the most used to combat these pests, but it reiterates that their use has caused tremendous pressure on ecosystems' self-cleansing capacity and resistance development by pathogens to synthetic fungicides. In the last decades, researchers have demonstrated the vast biological properties of plants against pathogens and diseases. Raphanus species (Brassicaceae) possesses antimicrobial, antioxidant, anti-inflammatory, anticancer, hepatoprotective, antidiabetic, insecticidal, nematicidal, allelopathic, and phytoremediators properties. These are due to the presence of structurally diverse bioactive compounds, such as flavonoids and glucosinolates. In this review, we have provided an update on the biological properties of two Raphanus species (R. sativus and R. raphanistrum), detailing the type of natural product (extract or isolated compound), the bioassays displayed, and the results obtained for the main bioactivities of this genus cited in the literature during the last 30 years. Moreover, preliminary studies on phytopathogenic activities performed in our laboratory have also been depicted. We conclude that Raphanus species could be a source of natural bioactive molecules to treat phytopathogens and weeds that affect crops and remediate contaminated soils.

In Vitro Antifungal Screening of Argentine Native or Naturalized Plants against the Phytopathogen Monilinia fructicola.

BACKGROUND: One of the main problems that fruit health has gone through in recent years is the problematic eradication of their fungal pathogens during crops or the post-harvest stage. This concerns the whole world because it represents huge production losses, fruit export restrictions, and consumer distrust. Consequently, new alternatives are sought to avoid the increasing use of fungicides that cause important damage to fruit consumers and the environment. One of the alternatives to solve this problem could be exploring plants and their active compounds applied to the treatment of fruit health. MATERIALS AND METHODS: This article describes peach production worldwide and particularly in Argentina, in addition to the main fungal rot that causes the greatest economic losses. Furthermore, experimental in-vitro studies of 69 extracts obtained from 18 plants growing in the central region of Argentina were displayed against the devastating fungus Monilinia fructicola, which greatly affects stone fruits. A simple and effective method developed in agar plate was applied to evaluate a large number of samples in a short time. RESULTS: The results showed that approximately 36% of the samples tested were strongly active against this pathogen, 12% were moderately active, and 52% demonstrated to be inactive. CONCLUSION: These findings support the possible use of natural products for fruit health and the importance of deepening in this field of science.

Botanical Control of Citrus Green Mold and Peach Brown Rot on Fruits Assays Using a Persicaria acuminata Phytochemically Characterized Extract.

Persicaria acuminata (Polygonaceae) is a perennial herb that grows in the central area of Argentina and it is commonly used by native populations to heal infected wounds and other conditions related to fungal infections. In this article, we explored the in vitro antifungal activity of its ethyl acetate extract against a panel of three fruit phytopathogenic fungi including: Penicillium digitatum, P. italicum, and Monilinia fructicola. The sesquiterpenes isolated from the extract were also evaluated against these strains, demonstrating that the dialdehyde polygodial was the responsible for this activity. In order to encourage the use of the extract rather than the pure compound, we displayed ex vivo assays using fresh oranges and peaches inoculated with P. digitatum and M. fructicola, respectively, and subsequently treated by immersion with an extract solution of 250 and 62.5 µg/mL, respectively. There were no statistically significant differences between the treatments with commercial fungicides and the extract over the control of both fruit rots. The concentration of the active compound present in the extract used on fruit experiments was determined by Gas Chromatography-Mass Spectroscopy. Finally, cytotoxicity evaluation against Huh7 cells showed that P. acuminata extract was less cytotoxic than the commercial fungicides at the assayed concentrations. After these findings we could conclude that a chemically characterized extract of P. acuminata should be further developed to treat fungal diseases in fruits from an agro-ecological model.