Eduardo Alves

Light quality is a key environmental factor regulating plant physiology, acting both as an energy source for photosynthesis and as a signal controlling growth and development through photoreceptors. This study evaluated the effects of different LED light qualities (white, blue, purple, and red) on the biometric, physiological, biochemical, elemental, and anatomical characteristics of cladodes of Selenicereus undatus (Haw.) D.R. Hunt and Hylocereus polyrhizus (Salm-Dyck) R. Bauer (Cactaceae) micropropagated in vitro and cultured on MS medium for 65 days. Growth parameters, photosynthetic pigments, bioactive compounds, mineral composition, and anatomical traits were assessed. Selenicereus undatus showed greater biometric performance, with higher cladode diameter, shoot length, and biomass accumulation, particularly under purple and red light. In contrast, H. polyrhizus exhibited higher accumulation of photosynthetic pigments, especially under white light. Raman spectral analysis indicated treatment-dependent variation in carotenoid-related profiles in S. undatus , whereas H. polyrhizus showed stronger responses under purple and white light. Elemental analysis identified potassium as the predominant element in both species; however, S. undatus showed higher relative accumulation of Mg, P, Cl, and Zn, while H. polyrhizus exhibited higher levels of K, Ca, S, Fe, and Na. Principal component analysis revealed treatment-dependent variation in elemental profiles, with red light associated with higher relative Na and Cl, and blue light associated with higher relative Fe and Mn. Overall, purple and red light were associated with stronger growth responses in S. undatus , whereas white and blue light were more favorable for H. polyrhizus . These findings highlight species-specific responses to LED light environments and provide a basis for optimizing in vitro cultivation strategies for pitaya. Because light intensity was estimated using lux-based measurements and literature-derived conversion factors, PPFD values among treatments should be interpreted as approximate, and observed responses may reflect combined effects of spectral composition and estimated photon flux density.

Pyricularia oryzae Triticum lineage (PoTl), the fungal pathogen responsible for wheat blast disease, has demonstrated increased fitness, stable resistance to quinone outside inhibitor (QoI) fungicides, and no associated fitness cost in the absence of fungicide selection pressure. In this study, we assessed whether the fitness-related epidemiological traits and competitive abilities of QoI-resistant (R) PoTl isolates increased or remained unchanged under continuous QoI applications across multiple disease infection cycles in wheat plants, compared to untreated plants. Approximately 48 h before inoculating each group of QoI-R or sensitive (S) PoTl isolates, wheat plants were treated with 10 μg mL⁻¹ azoxystrobin. The EC₅₀, incubation and latent periods, as well as the germination capacity of the QoI-R isolates inoculated on wheat leaves treated with 10 μg mL⁻¹ azoxystrobin, remained unchanged throughout five successive infection cycles. However, continuous azoxystrobin applications throughout successive disease cycles increased head blast severity by 1.33-fold and conidial production on wheat leaves by 36.8-fold in QoI-resistant (QoI-R) PoTl isolates compared with untreated plants. Conidia germination and germ tube development by QoI-R isolates on the abaxial surface of wheat leaves and/or head rachis treated with 10 μg mL⁻¹ azoxystrobin, six hours after inoculation (h.a.i), were observed using a scanning electron microscope (SEM). These findings demonstrate that repeated azoxystrobin exposure enhances fitness-related epidemiological traits of QoI-R PoTl isolates. Consequently, alternative evolutionarily informed disease management strategies, including fungicide rotation, multisite fungicides, and integrated disease management, are urgently needed.

Euterpe edulis Martius (Arecaceae) is a native species of the Atlantic Forest hotspot with ecological and economic relevance. Its fruits contribute to biodiversity maintenance by feeding birds and mammals and are valued for their antioxidant properties and applications in the food and cosmetic industries. However, habitat loss and propagation constraints have contributed to the threatened status of this species, reinforcing the need for complementary ex situ conservation strategies. Thus, this study evaluated the cryopreservation of somatic embryos of E. edulis using conventional vitrification and droplet vitrification in association with a modified Plant Vitrification Solution 3 (PVS3) supplemented with different concentrations of dimethyl sulfoxide (DMSO; 0, 5, 10, and 15%). No significant differences were observed between vitrification methods regarding post-thaw recovery. However, PVS3 supplemented with 10% and 15% DMSO promoted higher survival than 0% and 5%, with maximum values recorded at 15% DMSO (67.50% in droplet vitrification and 69.50% in conventional vitrification). Scanning electron microscopy revealed greater structural alterations in somatic embryos at more advanced maturation stages after cryopreservation, whereas transmission electron microscopy showed treatment-dependent differences in cellular ultrastructure, including vacuolization, cell wall disruption, and preservation of nuclear organization in surviving cells. Elemental analysis by energy-dispersive X-ray spectroscopy (EDS) revealed differences among cryopreservation treatments, with higher carbon intensity observed in treatments showing greater post-thaw survival and lower carbon intensity associated with reduced survival. This technique demonstrates potential for preserving germplasm of endangered E. edulis adult plants and can strategically support genetic improvement programs.

White rot, caused by Stromatinia cepivora , remains one of the most challenging soil-borne diseases affecting onion crops due to the long-term persistence of sclerotia and the limited effectiveness of conventional fungicide treatments.

Tabebuia heterophylla Hemsl.: Bignoniaceae (ipê rosa) é uma espécie arbórea exótica amplamente utilizada na arborização urbana brasileira. Constatou-se a ocorrência de superbrotação de ramos maduros, nanismo e declínio em exemplares jovens e adultos de T. heterophylla existentes na arborização pública da cidade de Belo Horizonte, MG. Este trabalho relata a identificação do agente causal desta doença e apresenta perspectivas de manejo, prevenção e controle da vassoura de bruxa de Tabebuia heterophylla na arborização urbana. Estacas caulinares de árvores sintomáticas e assintomáticas foram coletadas em áreas públicas (ruas e praças) de Belo Horizonte, MG e submetidas a Microscopia Eletrônica de Varredura (MEV) e testes de nested-PCR para detecção de fitoplasmas. Concluiu-se que Candidatus Phytoplasma sp. é o agente etiológico associado à vassoura de bruxa de T. heterophylla (ThWB). Propõe-se a adoção de medidas de manejo integrado como a restrição do plantio de mudas de T. heterophylla na arborização urbana, inspeção de viveiros florestais para evitar uso de material propagativo contaminado, estabelecimento de medidas de quarentena e eliminação de plantas doentes ou sintomáticas. Novos estudos devem ser realizados com o objetivo de identificar as espécies de insetos vetores da ThWB e também obter informações adicionais sobre a distribuição dessa fitoplasmose no município. O desenvolvimento de testes de campo para a detecção de plantas infectadas com ThWB é uma prioridade para evitar a disseminação de material de propagação contaminado.

Wheat blast, caused by Pyricularia oryzae Triticum lineage (PoTl), is one of the most destructive and significant fungal diseases affecting wheat crops. The stability of the G143A mutation in the cytB gene, which confers resistance to Quinone outside inhibitor fungicides (QoIs) in PoTl isolates, has not been extensively studied. This study was conducted to evaluate the stability of fungicide resistance, fitness, and competitive ability of the QoI-resistant (R) PoTl isolates group over nine and five consecutive transfer cycles in vitro and in vivo, respectively, without fungicide exposure. No changes in azoxystrobin sensitivity were observed in either the QoI-resistant or sensitive (S) PoTl isolate groups after the successive transfer cycles in vitro and in vivo. The mycelial growth of the QoI-R PoTl isolate group remained stable, while the conidial germination capacity increased over time. For the QoI-resistant isolates, leaf and head disease, conidial production, and the latent period on wheat leaves did not change between the first and fifth infection cycles. In each transfer cycle, the highest levels of leaf and head disease, as well as the largest quantities of conidia collected from wheat leaves, were observed in isolate mixtures. Also, the G143A mutation responsible for QoI resistance remained stable after five transfer cycles of the QoI-resistant (0S:100R) isolate on wheat leaves. Our findings indicate that the G143A mutation remains stable, and there are adaptive benefits in QoI-R PoTl isolates. We discuss the ecological implications of the wheat blast population’s adaptation and PoTl QoIs resistance stability in wheat-cropping areas in Brazil.

Although plant breeding and chemical approaches contribute to disease control, they are not able to completely contain it, due to the ability of the pathogen to resist against the fungicides and may overcome the resistance offered by plants of certain genotypes. Endophytic Penicillium citrinum strains GP1 and GP3, inoculated on seeds before sowing or sprayed on leaves, reduced the severity of rice blast while improving the growth of rice plants from cultivar BRSMG Caçula. Rice seed treatment with conidia of P. citrinum GP3, prior to seeding, led to a 58% reduction of blast severity. An association of GP1 and GP3 applied via seed treatment or foliar spray decreased blast severity by 33 and 37%, respectively. The area under the disease progress curve of the treatment of seeds (T5) with GP3 was lower than other treatments. For plant growth promotion, the association of GP1 and GP3 significantly enhanced the number of tillers per plant with 11 as compared to control, 10. Microscopic analysis revealed the endophytic colonization of rice root tissues by Penicillium GP1 and GP3. The P. citrinum reduced blast in rice plants while improving their fitness.