Polymerase Chain Reaction-Assisted Evaluation of the Efficacy of Seed-Treatment Prevention of Sporisorium reilianum Infection in Sorghum Seedlings

Head smut, caused by Sporisorium reilianum [(Kuhn) Langdon and Fullerton], is a major disease of sorghum. Seed treatment is considered to be the most effective way to control the disease; however, the pathogen can infect at the seedling stage and the infected plant will not display symptoms until the reproductive stage is reached. The evaluation of the efficacy of seed treatments is time consuming and is dependent upon visible symptoms. Polymerase chain reaction (PCR) methods have the ability to identify pathogens and diagnose their presence at an early stage of infection. In this study, the S. reilianum-specific primer SR3 was used for PCR detection pathogen. We optimized temperature, humidity, and spore quantity test conditions and were able to achieve >88% infection incidence in sorghum seedlings. Sorghum seeds were soaked in various concentrations of tebuconazole and planted for 7 days in soil containing 0.2% teliospores. The efficacy of tebuconazole against S. reilianum was evaluated by PCR and recorded as disease incidence. Results indicated that the reduction in disease incidence after exposure to 0.15, 0.30, 0.45, 0.60, and 0.75 μg/mL tebuconazole was 6.24, 37.48, 67.74, 81.24, and 93.74%, respectively. Significant differences between the concentrations of tebuconazole were observed. The PCR assay represents a valuable tool for evaluating the efficacy of fungicide seed treatments for the control of S. reilianum in sorghum under laboratory conditions.

Characterization of The Physicochemical Properties, Antioxidant Activity, And Antiproliferative Activity of Natural Melanin From S. Reiliana

This study aimed to characterize the physicochemical properties and stability of L-25 melanin extracted from Sporisorium reilianum (S. reiliana). The results showed that the maximum absorption wavelength of melanin was 215 nm. Reducing agents, heat, light, microwaving, oxidants, and common food additives did not affect the melanin. Additionally, it has a good metal stability except Mn2+. The IR spectra revealed the presence of O-H, N-H, C=O, and C=C bonds as well as carboxyl, alcohol hydroxyl, and phenolic hydroxyl groups and a pyran ring. L-25 melanin could be defined as DL-hydroxy phenylalanine (DOPA)-melanin. The antioxidant and antiproliferative were also measured. The melanin has a specific stability and high antioxidant activity, including a strong DPPH free radical scavenging ability, and protected damaged HepG2 cells by reducing reactive oxygen species, malondialdehyde, and lactate dehydrogenase content. In conclusion, S. reilianum represents a novel source of melanin, that could be applied to health food or food additives. Our results show that melanin from S. reilianum is a natural pigment with good stability that has a great prospect of development and application, providing a theoretical basis and methods for its further processing and development as a functional food.

Fungal Pathogen Emergence: Investigations with an Ustilago maydis × Sporisorium reilianum Hybrid

The emergence of new fungal pathogens threatens sustainable crop production worldwide. One mechanism by which new pathogens may arise is hybridization. To investigate hybridization, the related smut fungi, Ustilago maydis and Sporisorium reilianum, were selected because they both infect Zea mays, can hybridize, and tools are available for their analysis. The hybrid dikaryons of these fungi grew as filaments on plates but their colonization and virulence in Z. mays were reduced compared to the parental dikaryons. The anthocyanin induction caused by the hybrid dikaryon infections was distinct, suggesting its interaction with the host was different from that of the parental dikaryons. Selected virulence genes previously characterized in U. maydis and their predicted S. reilianum orthologs had altered transcript levels during hybrid infection of Z. mays. The downregulated U. maydis effectors, tin2, pit2, and cce1, and transcription factors, rbf1, hdp2, and nlt1, were constitutively expressed in the hybrid. Little impact was observed with increased effector expression; however, increased expression of rbf1 and hdp2, which regulate early pathogenic development by U. maydis, increased the hybrid’s capacity to induce symptoms including the rare induction of small leaf tumors. These results establish a base for investigating molecular aspects of smut fungal hybrid pathogen emergence.

Transcriptome Profiles of Sporisorium reilianum during the Early Infection of Resistant and Susceptible Maize Isogenic Lines

The biotrophic fungus Sporisorium reilianum causes destructive head smut disease in maize (Zea mays L.). To explore the pathogenicity arsenal of this fungus, we tracked its transcriptome changes during infection of the maize seedling mesocotyls of two near-isogenic lines, HZ4 and HZ4R, differing solely in the disease resistance gene ZmWAK. Parasitic growth of S. reilianum resulted in thousands of differentially expressed genes (DEGs) compared with growth in axenic culture. The protein synthesis and energy metabolism of S. reilianum were predominantly enriched with down-regulated DEGs, consistent with the arrested hyphal growth observed following colonization. Nutrition-related metabolic processes were enriched with both up- and down-regulated DEGs, which, together with activated transmembrane transport, reflected a potential transition in nutrition uptake of S. reilianum once it invaded maize. Notably, genes encoding secreted proteins of S. reilianum were mostly up-regulated during biotrophy. ZmWAK-mediated resistance to head smut disease reduced the number of DEGs of S. reilianum, particularly those related to the secretome. These observations deepen our understanding of the mechanisms underlying S. reilianum pathogenicity and ZmWAK-induced innate immunity.

Antioxidant and antihypertensive activity of bovine whey protein concentrate enzymatic hydrolysates

Whey is a highly polluting by-product of cheese processing. However, it has valuable nutritional properties since it is a rich and balanced source of proteins and amino acids. Therefore, it has a broad range of functional properties that can be exploited for diverse applications. Research has shown how the enzymatic hydrolysis of whey proteins releases bioactive peptides. In the present study, the hydrolysis of whey protein concentrate (WCP) was performed using purified Sporisorium reilianum aspartyl protease (Eap1), commercial enzymes chymotrypsin (C) and trypsin (T), as well as different enzymatic combinations in order to determine which enzyme or combination allowed for the release of peptides presenting the highest antioxidant and antihypertensive activity levels; our results indicated that hydrolysis with Eap1 releases the best-performing peptides in comparison with individual enzymes and their combinations.

Gains in recurrent selection cycles for grain yield and resistance to head smut in maize

El basidiomiceto <em>Sporisorium reilianum</em> f. sp. <em>zeae</em> infecta al cultivo de maíz y causa importantes pérdidas en regiones donde existen condiciones propicias para el desarrollo de la enfermedad. En este trabajo se evaluó la respuesta a la selección de seis ciclos de selección recurrente de maíces de endospermo blanco y cinco ciclos de maíces de endospermo amarillo para caracteres agronómicos deseables, rendimiento de grano y resistencia al carbón de la espiga. Los diferentes ciclos en las dos poblaciones se obtuvieron siguiendo el método de selección recurrente de familias S1, los cuales fueron evaluados para determinar el avance genético. En un ensayo anexo, las poblaciones fueron inoculadas artificialmente para medir el progreso de la resistencia a la enfermedad y evaluar un nuevo método de inoculación. Se utilizó un diseño experimental de bloques completos al azar con tres repeticiones para el ensayo de rendimiento y dos repeticiones para el ensayo inoculado. Los ciclos evaluados en las dos poblaciones mostraron un incremento en la resistencia de 0.94 y 1.2% ciclo-1, una ganancia genética para rendimiento de grano de 272.9 y 620 kg ha-1 ciclo-1 para la población blanca y amarilla, respectivamente. Los resultados mostraron que la selección recurrente de familias S1 fue eficiente para mejorar el rendimiento de grano y resistencia al carbón de la espiga en ambas poblaciones.