First report of Colletotrichum chlorophyti causing soybean anthracnose in Brazil.

Soybean [Glycine max (L.) Merr.] is one of the world's five major food crops, and Brazil produces the highest share at around 42%. Anthracnose caused by Colletotrichum is an important limiting factor to soybean production. In November 2013, anthracnose symptoms, characterized by brown irregular-shaped lesions on petioles, stems, and pods were observed in soybean fields (1% of incidence) in Vera, Mato Grosso State, Brazil. From the five plants gathered in the field, three leaves along with their corresponding petioles were meticulously chosen for the removal of symptomatic tissues. Sampling of these tissues involved carefully cutting a 0.5 × 0.5 cm fragment in the lesion area. The fragments were disinfected with 70% ethanol for 1 min, followed by 1% sodium hypochlorite for 2 min. Then the fragments were rinsed three times in sterile distilled water, placed on water-agar, and incubated at 25 °C for four days, in a 12/12 h photoperiod. Hyphal tips were transferred to potato dextrose agar (PDA) plates and incubated as previously described for seven days. A Colletotrichum sp. single-spore isolate (LFN0461) was selected, grown, preserved in filter paper, and stored at -80 °C. In 2023, it was reactivated for molecular characterization. On PDA, colony showed a rough-like mycelial growth, violaceous-black (front/reverse), with curved-shaped conidia 14.7 - 28.2 × 2.1 - 8.96 µm (average 18.4 × 4.7 µm). The DNA was extracted from 10-day-old mycelium using the cetyltrimethylammonium bromide (CTAB) method. The rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone (HIS3), and ß-tubulin 2 (TUB2) regions were amplified by polymerase chain reaction (PCR), using the primer pairs ITS-1F + ITS-4 (Gardes and Bruns 1993; White et al. 1990), GDF1 + GDR1 (Guerber et al. 2003), CYLH3F + CYLH3R (Crous et al. 2006), and Bt2A + Bt2B (Glass and Donaldson 1995), respectively. The sequences were deposited in the GenBank database (accession numbers: PP209207 - ITS; PP213392 - GAPDH; PP213393 - HIS3; MN688797 - TUB2). The reconstruction of the multilocus phylogenetic tree revealed that the LFN0461 isolate clustered with C. cholorophyti reference strain (IMI 103806) with 99.9% of Bayesian probability. Given the seed-borne nature of soybean anthracnose (Boufleur et al. 2021; Yang et al. 2013), pathogenicity tests were carried out by soybean seeds inoculation. Fifty seeds of NS6220 IPRO (Nidera) cultivar were inoculated by water restriction method, with LFN0461 colonies grown on PDA amended with mannitol (Machado et al. 2004), while 50 seeds were placed on PDA amended with mannitol as negative control. Soybean seeds remained in contact with the inoculum for 48 hours. Subsequently, seeds were sown in 2 L pots (n = 10) containing sterilized substrate, which were placed in a greenhouse at 25 ± 5 ºC. After 10 days, inoculated soybean seedlings exhibited characteristic necrotic lesions on cotyledons and hypocotyls, while negative control plants remained asymptomatic. Colletotrichum chlorophyti was successfully reisolated from the symptomatic tissues. Currently, C. chlorophyti has been reported to cause soybean anthracnose and infect seeds in the United States (Yang et al. 2013, 2012). Although this pathogen has not been reported since our first observation in 2013 in Brazil, many Colletotrichum isolates are misidentified due to reliance on morphology (Boufleur et al. 2021). To our knowledge, this study is the first report of C. chlorophyti causing soybean anthracnose in Brazil, joining a new group of emergent Colletotrichum spp. associated with this disease.

Colletotrichum spp. from Soybean Cause Disease on Lupin and Can Induce Plant Growth-Promoting Effects.

Protein crop plants such as soybean and lupin are attracting increasing attention because of their potential use as forage, green manure, or for the production of oil and protein for human consumption. Whereas soybean production only recently gained more importance in Germany and within the whole EU in frame of protein strategies, lupin production is already well-established in Germany. The cultivation of lupins is impeded by the hemibiotrophic ascomycete Colletotrichum lupini, the causal agent of anthracnose disease. Worldwide, soybean is also a host for a variety of Colletotrichum species, but so far, this seems to not be the case in Germany. Cross-virulence between lupin- and soybean-infecting isolates is a potential threat, especially considering the overlap of possible soybean and lupin growing areas in Germany. To address this question, we systematically investigated the interaction of different Colletotrichum species isolated from soybean in Brazil on German soybean and lupin plant cultivars. Conversely, we tested the interaction of a German field isolate of C. lupini with soybean. Under controlled conditions, Colletotrichum species from soybean and lupin were able to cross-infect the other host plant with varying degrees of virulence, thus underpinning the potential risk of increased anthracnose diseases in the future. Interestingly, we observed a pronounced plant growth-promoting effect for some host-pathogen combinations, which might open the route to the use of beneficial biological agents in lupin and soybean production.

Genome Sequence Resources of Colletotrichum truncatum, C. plurivorum, C. musicola, and C. sojae: Four Species Pathogenic to Soybean (Glycine max).

Colletotrichum is a large genus of plant pathogenic fungi comprising more than 200 species. In this work, we present the genome sequences of four Colletotrichum species pathogenic to soybean: C. truncatum, C. plurivorum, C. musicola, and C. sojae. While C. truncatum is globally considered the most important pathogen, the other three species have been described and associated with soybean only recently. The genome sequences will provide insights into factors that contribute to pathogenicity toward soybean and will be useful for further research into the evolution of Colletotrichum.

Expression of Arabidopsis Bax Inhibitor-1 in transgenic sugarcane confers drought tolerance.

The sustainability of global crop production is critically dependent on improving tolerance of crop plants to various types of environmental stress. Thus, identification of genes that confer stress tolerance in crops has become a top priority especially in view of expected changes in global climatic patterns. Drought stress is one of the abiotic stresses that can result in dramatic loss of crop productivity. In this work, we show that transgenic expression of a highly conserved cell death suppressor, Bax Inhibitor-1 from Arabidopsis thaliana (AtBI-1), can confer increased tolerance of sugarcane plants to long-term (>20 days) water stress conditions. This robust trait is correlated with an increased tolerance of the transgenic sugarcane plants, especially in the roots, to induction of endoplasmic reticulum (ER) stress by the protein glycosylation inhibitor tunicamycin. Our findings suggest that suppression of ER stress in C4 grasses, which include important crops such as sorghum and maize, can be an effective means of conferring improved tolerance to long-term water deficit. This result could potentially lead to improved resilience and yield of major crops in the world.

Controle da podridão abacaxi da cana-de-açúcar por meio da pulverização de fungicidas em rebolos no sulco de plantio / Control of pineapple disease of sugarcane through in-furrow fungicide spray application on seedpieces

A podridão abacaxi da cana-de-açúcar, causada pelo fungo Thielaviopsis paradoxa, pode causar quedas de até 50% na brotação e de 42% na produtividade de colmos. O objetivo deste trabalho foi avaliar o controle da doença por meio da pulverização de fungicidas em rebolos no sulco de plantio. Para isso, foram instalados dois experimentos em casa de vegetação e um no campo. O substrato e o solo foram infestados com o patógeno antes do plantio da cana-de-açúcar e os fungicidas foram aplicados nos rebolos imediatamente após o plantio, com um pulverizador costal pressurizado com CO2. A pulverização dos rebolos no sulco de plantio mostrou-se eficaz no controle da podridão abacaxi com determinados fungicidas, trazendo incrementos na brotação e proporcionando recuperação de até 12% na produtividade. Dentre os tratamentos testados, os fungicidas piraclostrobina + epoxiconazol; piraclostrobina e propiconazol mostraram bom potencial no controle da doença.

Sugarcane pineapple disease, caused by the fungus Thielaviopsis paradoxa, can cause germination and yield decreases of up to 50% and 42%, respectively. The aim of this research was to assess the control of this disease through in-furrow fungicide application on seedpieces. Two experiments were installed in greenhouse and one under field conditions with this purpose. The substrate and the soil were infested with the pathogen before the sugarcane planting and the fungicides were sprayed on seedpieces immediately after the planting with a CO2 backpack sprayer. Seedpieces in-furrow spraying was effective in controlling the pineapple disease with certain fungicides, providing up to 12% yield recovery. Among the tested treatments, the fungicides pyraclostrobin + epoxiconazole; pyraclostrobin and propiconazole showed good potential for pineapple disease control.