Sporisorium Reilianum Research Articles

Optimization of ultrasound‐assisted extraction of melanin and its hypoglycemic activities from Sporisorium reilianum

Sporisorium reilianum (S. reiliana) is rich in nutrition, high in melanin content, and can be obtained by artificial species. It is a high-quality raw material for extracting natural melanin. Because of its unique structure and physicochemical property, natural melanin has become a stable and unique rare species in natural pigments. In this study, the effect of ultrasonic assisted on melanin extraction was studied with S. reiliana as a material. The influences of ultrasonic power, temperature, time, NaOH extract on melanin extraction in S. reiliana were investigated respectively. And through the single factor test and response surface method (RSM) to verify the evaluation. The RSM optimum conditions for melanin accumulation were: Ultrasonic power 245W, temperature 50°C, time 2 h, and pH 13 of NaOH extract. Under this condition, the return is 3.52%, which is close to the predicted value, indicating the feasibility of this model. For α-glycosidase and PTP1B inhibition assay, the melanin demonstrated the inhibitory effect with IC50 82.16 ± 5.02 μg/ml and 81.27 ± 10.48 μg/ml, respectively. This study reveals the hypoglycemic activities of the melanin isolated from S. reiliana for the first time. Practical applications Melanin from S. reiliana is an excellent hypoglycemic product due to its high α-glycosidase and PTP1B inhibition activity. However, its extraction yield is too low. The combination of unconventional techniques (ultrasound-assisted alkali dissolution and acid precipitation) is characterized as a new methodology for the extraction of melanin from S. reiliana. The extract provided a higher content of melanin than conventional methods. This technique is easily incorporated at the industrial level and is the low cost after the purchase of the relevant equipment.

Hypomyces chrysospermus ACL-01 aislado a partir de Boletus edulis y su efecto sobre hongos patógenos de cereales

In this study, a Hypomyces chrysospermus ACL-01 fungus was isolated from the fruiting body of edible basidiomycete Boletus edulis, collected in Acaxochitlan in the State of Hidalgo, Mexico popularly known as tlacoayel. The effect of the isolated fungus against different fungal cereal pathogens was evaluated. The dual confrontation test and scanning electron microscopy analysis revealed that this ascomycete grows on the basidiomycetes Sporisorium reilianum and Tilletia sp., causing loss of cell viability. However, for the ascomycetes Bipolaris sorokiniana and Pyrenophora teres f. teres no effect was observed. On other hand Stenocarpella maydis and Fusarium sp. inhibited the development of H. chrysospermus ACL-01. The isolated strain produced extracellular enzymatic activities of the acid and basic proteases, chitinase and laccase. Cellulase and lipase activities were not found.

Molecular Variation of the Phytopathogenic Fungus Sporisorium reilianum in Valle del Mezquital, Hidalgo

Head smut in maize (Zea mays) is a systemic disease caused by the phytopathogenic fungus Sporisorium reilianum. One of the most severely-affected regions in Mexico is Valle del Mezquital in the state of Hidalgo, a high production zone with irrigated agriculture that produces over 50% of maize supplies in the state. This study was designed to analyze the genetic diversity of this phytopathogen isolated from different zones of Valle del Mezquital using the following molecular markers: ITS, aspartyl protease, β-tubulin and the mitochondrial endonuclease LAGLIDADG. Our objective was to estimate the level of genetic variability in a regional space and understand the evolutionary processes to which non-model organisms are subjected. A total of 53 strains of S. reilianum were isolated from the sampling sites and then purified. A Bayesian Analysis of Population Structure (BAPS) analysis of the genetic structuring allowed us to recover three genetic groupings (K = 3), while molecular variance analysis showed a very low fixation index (FST = 0.0146), which was not statistically significant and indicated little between-group genetic differentiation. Also, the value determined for the coefficient of genetic differentiation (Gst) showed little variation among the genetic groups, while the gene flow number (Nm) was 8.25. The Tajima´s D estimator and haplotype network recently indicated a rapid population expansion. Together, these results suggest that reproduction and migration are key factors in the evolution and virulence of this fungus.

Screening of Secreted Proteins of Sporisorium reilianum f. sp. zeae for Cell Death Suppression in Nicotiana benthamiana.

Sporisorium reilianum f. sp. zeae (SRZ) is a biotrophic fungus causing head smut in maize. Maize infection with SRZ leads to very little cell death suggesting the presence of cell-death suppressinpg effectors. Several hundred effector proteins have been predicted based on genome annotation, genome comparison, and bioinformatic analysis. For only very few of these effectors, an involvement in virulence has been shown. In this work, we started to test a considerable subset of these predicted effector proteins for a possible function in suppressing cell death. We generated an expression library of 62 proteins of SRZ under the control of a strong constitutive plant promoter for delivery into plant cells via Agrobacterium tumefaciens-mediated transient transformation. Potential apoplastic effectors with high cysteine content were cloned with signal peptide while potential intracellular effectors were also cloned without signal peptide to ensure proper localization after expression in plant cells. After infiltration of Nicotiana benthamiana leaves, infiltration sites were evaluated for apparent signs of hypersensitive cell death in absence or presence of the elicitin INF1 of Phytophthora infestans. None of the tested candidates was able to induce cell death, and most were unable to suppress INF1-induced cell death. However, the screen revealed one predicted cytoplasmic effector (sr16441) of SRZ that was able to reliably suppress INF1-induced cell death when transiently expressed in N. benthamiana lacking its predicted secretion signal peptide. This way, we discovered a putative function for one new effector of SRZ.

Structural analysis and potential anti-tumor activity of Sporisorium reilianum (Fries) polysaccharide

A neutral polysaccharide WM-NP-60 was successfully isolated and purified from a phytopathogenic fungus Sporisorium reilianum (Fries). The characteristics and potential antitumor activities of WM-NP-60 were studied. WM-NP-60 was a water-soluble polysaccharide. The molecular weight of WM-NP-60 was 15.6 kDa. The main chain of WM-NP-60 was composed of β-1,6-D-Glcp and its side chains were β-1,3-D-Glcp. The side chains bound to the main chain with glycosyl groups at the C-3 positions. Gal might be attached to the backbone as a side chain or bound to the linear β-1,3-D-Glcp side chain. WM-NP-60 could inhibit the proliferation of HepG2 and SGC7901 cells in a dose-dependently manner. In addition, it was found that WM-NP-60 triggered the HepG2 and SGC7901 cell cycle arrest at the G1 phase and induced apoptosis of HepG2 and SGC7901 cells. Taken together, these results suggested that WM-NP-60 possessed a tumor-suppressive activity and might be regarded as a potential natural anti-tumor drug.

Multicellular growth of the Basidiomycota phytopathogen fungus Sporisorium reilianum induced by acid conditions.

Fungi are considered model organisms for the analysis of important phenomena of eukaryotes. For example, some of them have been described as models to understand the phenomenon of multicellularity acquisition by different unicellular organisms phylogenetically distant. Interestingly, in this work, we describe the multicellular development in the model fungus S. reilianum. We observed that Sporisorium reilianum, a Basidiomycota cereal pathogen that at neutral pH grows with a yeast-like morphology during its saprophytic haploid stage, when incubated at acid pH grew in the form of multicellular clusters. The multicellularity observed in S. reilianum was of clonal type, where buds of "stem" cells growing as yeasts remain joined by their cell wall septa, after cytokinesis. The elaboration and analysis of a regulatory network of S. reilianum showed that the putative zinc finger transcription factor CBQ73544.1 regulates a number of genes involved in cell cycle, cellular division, signal transduction pathways, and biogenesis of cell wall. Interestingly, homologous of these genes have been found to be regulated during Saccharomyces cerevisiae multicellular growth. In adddition, some of these genes were found to be negatively regulated during multicellularity of S. reilianum. With these data, we suggest that S. reilianum is an interesting model for the study of multicellular development.

Study of the intracellular xylanolytic activity of the phytopathogenic fungus Sporisorium reilianum

Abstract The present study demonstrates that Sporisorium reilianum, a phytopathogenic fungus of corn, produces intracellular xylanolytic activity during submerged fermentation. Production reached its highest levels in a medium containing glucose, corn hemicellulose and yeast extract. An intracellular xylanase was purified by a process that included precipitation with ammonium sulfate, ion exchange chromatography and gel filtration. Optimal pH and temperature values were 5.0 and 60 °C, respectively. The enzyme showed activity through a broad pH range. The molecular weights of pure xylanase were 36 and 37 kDa, determined by SDS PAGE and gel filtration, respectively. Km and Vmax were 0.160 mg/mL and 1.564 μmol/min/mg, respectively, on a substrate of birchwood xylan. SDS, EDTA, β-Mercaptoethanol, Tween 80, Triton and Mn2+ and Ca2+ strongly inhibited activity. The purified enzyme hydrolyzed xylan, releasing xylotriose and xylobiose. Sequence protein analysis showed 95% similarity with the theoretical protein encoded by the sr14403 gene of S. reilianum, which encodes a putative endo-β-1,4-xylanase. The enzyme is an isoform of the extracellular xylanase SRXL1 of this basidiomycete.

Trichoderma posible micoparásito de Sporisorium reilianum y su influencia en el rendimiento de maíz

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><strong>Objetivo - </strong><span>evaluar el efecto de cepas de </span><em>Trichoderma </em><span>en el control de </span><em>Sporisorium reilianum </em><span>y aumentar el rendimiento en un cultivo de maíz en el Valle del Mezquital, Hidalgo.</span></p><p><strong>Método - </strong><span>se desarrollaron experimentos </span><span><em>in vitro</em> e <em>in vivo</em></span><span>, las variables evaluadas fueron colonización por </span><em>Trichoderma </em><span>en cultivos duales, Incidencia, colonización de tejidos vegetales, altura y rendimiento. Los resultados serán relevantes para las regiones templadas donde se establezca maíz. </span></p><p><span><strong>Resultados - </strong></span><span>se demostró </span><em>in vitro </em><span>que el patógeno fue controlado principalmente por las cepas C5THBr y C3VM14. En incidencia en el cultivo, el tratamiento con el cual se obtuvo el mejor resultado fue con la cepa C4TVBr-no nativa (8.31%). Los tejidos fueron colonizados por </span><em>Trichoderma </em><span>desde un 19.99% (hojas) hasta un 53.3% (raíces). A excepción de C3VM14 todos los tratamientos tuvieron efecto positivo en altura de plantas. Con la cepa C5THBr-no nativa hubo un aumento de rendimiento de un 38.8%. </span></p><p><strong>Limitaciones - </strong><span>se requieren estudios detallados sobre los mecanismos de acción de las cepas en estudio. </span></p><p><strong>Principales hallazgos - </strong><span>las cepas de </span><span><em>Trichoderma</em> </span><span>tanto nativas como no nativas pueden tener un efecto en el control de </span><em>Sporisorium reilianum </em><span>así como en el aumento del rendimiento del cultivo del maíz. </span></p></div></div></div>

Molecular Interactions Between Smut Fungi and Their Host Plants.

Smut fungi are a large group of biotrophic plant pathogens that infect mostly monocot species, including economically relevant cereal crops. For years, Ustilago maydis has stood out as the model system to study the genetics and cell biology of smut fungi as well as the pathogenic development of biotrophic plant pathogens. The identification and functional characterization of secreted effectors and their role in virulence have particularly been driven forward using the U. maydis-maize pathosystem. Today, advancing tools for additional smut fungi such as Ustilago hordei and Sporisorium reilianum, as well as an increasing number of available genome sequences, provide excellent opportunities to investigate in parallel the effector function and evolution associated with different lifestyles and host specificities. In addition, genome analyses revealed similarities in the genomic signature between pathogenic smuts and epiphytic Pseudozyma species. This review elaborates on how knowledge about fungal lifestyles, genome biology, and functional effector biology has helped in understanding the biology of this important group of fungal pathogens. We highlight the contribution of the U. maydis model system but also discuss the differences from other smut fungi, which raises the importance of comparative genomic and genetic analyses in future research.

Analysis of Cytology and Expression of Resistance Genes in Maize Infected with Sporisorium reilianum.

Head smut, caused by the fungus Sporisorium reilianum, is a devastating global disease of maize (Zea mays). In the present study, maize seedlings were artificially inoculated with compatible mating-type strains of S. reilianum by needle inoculation of mesocotyls (NIM) or by soaking inoculation of radicles (SIR). After NIM or SIR, Huangzao4 mesocotyls exhibited severe damage with brownish discoloration and necrosis, whereas Mo17 mesocotyls exhibited few lesions. Fluorescence and electron microscopy showed that S. reilianum infected maize within 0.5 day after SIR and mainly colonized the phloem. With longer incubation, the density of S. reilianum hyphae increased in the vascular bundles, concentrated mainly in the phloem. In Mo17, infected cells exhibited apoptosis-like features, and hyphae became sequestered within dead cells. In contrast, in Huangzao4, pathogen invasion resulted in autophagy that failed to prevent hyphal spreading. The growth of S. reilianum hyphae diminished at 6 days after inoculation when expression of the R genes ZmWAK and ZmNL peaked. Thus, 6 days after SIR inoculation might be an important time for inhibiting the progress of S. reilianum infection in maize. The results of this study will provide a basis for further analysis of the mechanisms of maize resistance to S. reilianum.

Genome wide association analysis of sorghum mini core lines regarding anthracnose, downy mildew, and head smut.

In previous studies, a sorghum mini core collection was scored over several years for response to Colletotrichum sublineola, Peronosclerospora sorghi, and Sporisorium reilianum, the causal agents of the disease anthracnose, downy mildew, and head smut, respectively. The screening results were combined with over 290,000 Single nucleotide polymorphic (SNP) loci from an updated version of a publicly available genotype by sequencing (GBS) dataset available for the mini core collection. GAPIT (Genome Association and Prediction Integrated Tool) R package was used to identify chromosomal locations that differ in disease response. When the top scoring SNPs were mapped to the most recent version of the published sorghum genome, in each case, a nearby and most often the closest annotated gene has precedence for a role in host defense.

Kinetics and regioselectivity of three GH62 α-L-arabinofuranosidases from plant pathogenic fungi

BackgoundXylan is the second most abundant plant cell wall polysaccharide after cellulose with α-L-arabinofuranose (L-Araf) as one of the major side substituents. Capacity to degrade xylan is characteristic of many plant pathogens; and corresponding enzymes that debranch arabinoxylan provide tools to tailor xylan functionality or permit its full hydrolysis. MethodThree GH62_2 family α-arabinofuranosidases (Abfs) from plant pathogenic fungi, NhaAbf62A from Nectria haematococca, SreAbf62A from Sporisorium reilianum and GzeAbf62A from Gibberella zeae, were recombinantly produced in Escherichia coli. Their biochemical properties and substrate specificities were characterized in detail. Particularly with 1H NMR, the regioselectivity and debranching preference of the three Abfs were directly compared. ResultsThe activities of selected Abfs towards arabinoxylan were all optimal at pH 6.5. Their preferred substrates were wheat arabinoxylan, followed by soluble oat spelt xylan. The Abfs displayed selectivity towards either α-(1 → 2) or α-(1 → 3)-L- Araf mono-substituents in arabinoxylan. Specifically, SreAbf62A and GzeAbf62A removed m-α-(1 → 3)-L-Araf and m-α-(1 → 2)-L-Araf substituents with a similar rates, whereas NhaAbf62A released m-α-(1 → 3)-L-Araf 1.9 times faster than m-α-(1 → 2)-L-Araf. Major conclusionsBuilding upon the known selectivity of GH62 family α-arabinofuranosidases towards L-Araf mono-substituents in xylans, the current study uncovers enzyme-dependent preferences towards m-α-(1 → 3)-L-Araf and m-α-(1 → 2)-L-Araf substitutions. Comparative sequence-structure analyses of Abfs identified an arginine residue in the xylose binding +2R subsite that was correlated to the observed enzyme-dependent L-Araf debranching preferences. General significanceThis study expands the limited pool of characterized GH62 Abfs particularly those from plant pathogenic fungi, and provides biochemical details and methodology to evaluate regioselectivity within this glycoside hydrolase family.

The smut fungus Ustilago esculenta has a bipolar mating system with three idiomorphs larger than 500 kb

Zizania latifolia Turcz., which is mainly distributed in Asia, has had a long cultivation history as a cereal and vegetable crop. On infection with the smut fungus Ustilago esculenta, Z. latifolia becomes an edible vegetable, water bamboo. Two main cultivars, with a green shell and red shell, are cultivated for commercial production in Taiwan. Previous studies indicated that cultivars of Z. latifolia may be related to the infected U. esculenta isolates. However, related research is limited. The infection process of the corn smut fungus Ustilago maydis is coupled with sexual development and under control of the mating type locus. Thus, we aimed to use the knowledge of U. maydis to reveal the mating system of U. esculenta. We collected water bamboo samples and isolated 145 U. esculenta strains from Taiwan’s major production areas. By using PCR and idiomorph screening among meiotic offspring and field isolates, we identified three idiomorphs of the mating type locus and found no sequence recombination between them. Whole-genome sequencing (Illumina and PacBio) suggested that the mating system of U. esculenta was bipolar. Mating type locus 1 (MAT-1) was 552,895 bp and contained 44% repeated sequences. Sequence comparison revealed that U. esculenta MAT-1 shared high gene synteny with Sporisorium reilianum and many repeats with Ustilago hordei MAT-1. These results can be utilized to further explore the genomic diversity of U. esculenta isolates and their application for water bamboo breeding.

Mating type a locus alleles and genomic polymorphism in Sporisorium reilianum: comparison of sorghum isolates to those from maize

Sporisorium reilianum causes head smut in sorghum and maize and exists in two formae speciales, Sporisorium reilianum f. sp. reilianum and Sporisorium reilianum f. sp. zeae that have preference for sorghum and maize, respectively. Infection requires the formation of a dikaryon between sporidia of compatible mating types, leading to a change from yeast-like to hyphal growth within the host plant. This switching is controlled through mating type loci. A total of 66 sorghum isolates of S. reilianum collected from fields in different geographic regions and 2 maize isolates were examined for mating compatibility, leading to the establishment of haploid cultures with three different alleles at the a mating type locus, as verified by gene expression. Interestingly, a mating compatibility was detected between maize and sorghum isolates. Comparison of amino acid sequences, deduced from nucleotide sequencing of pheromone precursor genes of sorghum to the corresponding components in maize, showed 100% similarity of pheromone components mfa1.2, mfa2.1, mfa3.1 and 97% for mfa1.3, mfa3.2 and mfa2.3. Only 1 amino acid substitution was detected in sorghum mfa1.3. To assay host preference in relationship to whole genome polymorphism, six amplified fragment length polymorphism (AFLP) selective primer combinations were used on DNA of S. reilianum isolates. High genetic polymorphism (61%) was observed between sorghum and maize isolates. The resultant dendrogram constructed using neighbor-joining (NJ) analysis grouped maize isolates into one cluster with high similarity (>88%) while sorghum isolates grouped into four clusters suggesting that genetic differentiation contributes to host specific populations of S. reilianum.

Neofunctionalization of the secreted Tin2 effector in the fungal pathogen Ustilago maydis.

Plant-pathogenic fungi hijack their hosts by secreting effector proteins. Effectors serve to suppress plant immune responses and modulate the host metabolism to benefit the pathogen. Smut fungi are biotrophic pathogens that also parasitize important cereals, including maize1. Symptom development is usually restricted to the plant inflorescences. Ustilago maydis is an exception in its ability to cause tumours in both inflorescences and leaves of maize, and in inducing anthocyanin biosynthesis through the secreted Tin2 effector2,3. How the unique lifestyle of U. maydis has evolved remains to be elucidated. Here we show that Tin2 in U. maydis has been neofunctionalized. We functionally compared Tin2 effectors of U. maydis and the related smut Sporisorium reilianum, which results in symptoms only in the inflorescences of maize and fails to induce anthocyanin. We show that Tin2 effectors from both fungi target distinct paralogues of a maize protein kinase, leading to stabilization and inhibition, respectively. An ancestral Tin2 effector functionally replaced the virulence function of S. reilianum Tin2 but failed to induce anthocyanin, and was unable to substitute for Tin2 in U. maydis. This shows that Tin2 in U. maydis has acquired a specialized function, probably connected to the distinct pathogenic lifestyle of this fungus.

Sporisorium reilianum possesses a pool of effector proteins that modulate virulence on maize.

The biotrophic maize head smut fungus Sporisorium reilianum is a close relative of the tumour-inducing maize smut fungus Ustilago maydis with a distinct disease aetiology. Maize infection with S.reilianum occurs at the seedling stage, but spores first form in inflorescences after a long endophytic growth phase. To identify S.reilianum-specific virulence effectors, we defined two gene sets by genome comparison with U.maydis and with the barley smut fungus Ustilago hordei. We tested virulence function by individual and cluster deletion analysis of 66 genes and by using a sensitive assay for virulence evaluation that considers both disease incidence (number of plants with a particular symptom) and disease severity (number and strength of symptoms displayed on any individual plant). Multiple deletion strains of S.reilianum lacking genes of either of the two sets (sr10057, sr10059, sr10079, sr10703, sr11815, sr14797 and clusters uni5-1, uni6-1, A1A2, A1, A2) were affected in virulence on the maize cultivar 'Gaspe Flint', but each of the individual gene deletions had only a modest impact on virulence. This indicates that the virulence of S.reilianum is determined by a complex repertoire of different effectors which each contribute incrementally to the aggressiveness of the pathogen.

The cereal phytopathogen Sporisorium reilianum is able to infect the non-natural host Arabidopsis thaliana

We analyzed the infection of the model plant Arabidopsis thaliana by the basidiomycete phytopathogen of cereals Sporisorium reilianum in order to use it as an experimental pathosystem model. Sterile plantlets of A. thaliana were grown on MS solid medium, and inoculated with haploid strains or mixtures of sexually compatible S. reilianum strains. Inoculated plants showed growth of filaments within their tissues, size reduction, a drastic increase in the formation of lateral roots, and a high production of plant pigments. Although symptoms were more severe in plants infected with sexually compatible strains, no spores were formed by the fungus. Among the pigments accumulated in the stunted plants we identified the anthocyanins cyanidin, cyanidin 3-glucoside, malvidin and pelargonidin. Congruently, the anthocyanin biosynthesis genes: chalcone synthase (CHS, AT5G13930) and dihydroflavonol reductase (DFR, AT5G42800) were over-expressed. The three genes encoding flavin monooxygenases: YUCCA7 (YUC7, AT2G33230), YUCCA8 (YUC8, AT4G28720), and YUCCA9 (YUC9, AT1G04180), and the transcription factor Jagged Lateral Organs (JLO, AT4G00220), all of them involved in the biosynthesis of auxins specific for root development, were also positively regulated. These data provide evidence that both haploid and the mixture of sexually compatible strains of S. reilianum can infect plants of A. thaliana; evidencing the usefulness of this pathosystem for the study of the genetic and metabolic reactions involved in S. reilianum virulence.

The Ustilago maydis repetitive effector Rsp3 blocks the antifungal activity of mannose-binding maize proteins

To cause disease in maize, the biotrophic fungus Ustilago maydis secretes a large arsenal of effector proteins. Here, we functionally characterize the repetitive effector Rsp3 (repetitive secreted protein 3), which shows length polymorphisms in field isolates and is highly expressed during biotrophic stages. Rsp3 is required for virulence and anthocyanin accumulation. During biotrophic growth, Rsp3 decorates the hyphal surface and interacts with at least two secreted maize DUF26-domain family proteins (designated AFP1 and AFP2). AFP1 binds mannose and displays antifungal activity against the rsp3 mutant but not against a strain constitutively expressing rsp3. Maize plants silenced for AFP1 and AFP2 partially rescue the virulence defect of rsp3 mutants, suggesting that blocking the antifungal activity of AFP1 and AFP2 by the Rsp3 effector is an important virulence function. Rsp3 orthologs are present in all sequenced smut fungi, and the ortholog from Sporisorium reilianum can complement the rsp3 mutant of U. maydis, suggesting a novel widespread fungal protection mechanism.

Complementary DNA (cDNA) cloning and functional verification of resistance to head smut disease (Sphacelotheca reiliana) of an NBS–LRR gene ZmNL in maize (Zea mays)

The nucleotide-binding site (NBS)-leucine-rich repeat (LRR) gene family comprises the largest number of known disease resistance (R) genes and is one of the largest gene families in plants. In the present study, the full-length cDNA of ZmNL (GenBank Accession Number KF765443) was isolated using Rapid Amplification of cDNA Ends. The nucleotide sequence of ZmNL contains an open reading frame of 3156 bp that encodes the ZmNL protein, which is comprised of 1051 amino acid residues. This putative protein has high homology to other known resistance proteins (84% to Triticum aestivum LR10) and belongs to the CC–NBS–LRR type R gene family. The ZmNL gene was introduced into the maize inbred line of Huangzao4 which was highly susceptible to head smut under the control of the maize ubiquitin promoter by Agrobacterium-mediated transformation. The head smut disease incidence of 3 T2 transgenic lines was significantly reduced (by 18.38–29.40%) compared with the wild type, which indicated that the overexpression of ZmNL gene in maize enhanced the resistance to the fungus Sporisorium reilianum (Kuhn) Clint of these plants.

Resistencia genética a Sporisorium reilianum f. sp. zeae en líneas seleccionadas de maíz (Zea mays L.) con endospermo blanco y amarillo

<p>El carbón de la espiga (<em>Sporisorium reilianum </em>f. sp. <em>zeae</em>) del maíz (<em>Zea mays</em> L.) es una enfermedad de gran importancia que se presenta en zonas productoras de maíz, incluyendo los Valles del Mezquital y Toluca. El objetivo del presente estudio fue identificar líneas C<sub>2</sub>-S<sub>1</sub> y C<sub>2</sub>-S<sub>2</sub> de maíz adaptadas al Altiplano de México para ser utilizadas en un programa de mejoramiento de resistencia y buenas características agronómicas. Semillas de cada línea se inocularon con una suspensión de 1.7x10<sup>7</sup> mL<sup>-1</sup> teliosporas de <em>S. reilianum </em>f. sp. <em>zeae</em> en 1% de carboximetilcelulosa de sodio y se sembraron en invernadero. Las plantas fueron monitoreadas hasta la formación de espiga, donde se evaluó la incidencia. En 258 líneas C<sub>2</sub>-S<sub>1</sub> de endospermo blanco se presentó hasta 92.3% de incidencia y hasta 41.7% en 71 líneas de endospermo amarillo. Con base en la incidencia y características agronómicas, se seleccionaron y autofecundaron en campo 38 líneas C<sub>2</sub>-S<sub>1</sub> de endospermo blanco y 24 de endospermo amarillo. Un total de 123 y 114 líneas C<sub>2</sub>-S<sub>2</sub> de endospermo blanco y amarillo, respectivamente, fueron inoculadas con teliosporas del patógeno y presentaron una incidencia de la enfermedad de hasta 42.8% y 28.5%, respectivamente. La inoculación con teliosporas y siembra en invernadero permitió identificar líneas de maíz con diferente porcentaje de infección y seleccionar las líneas resistentes, probando la eficiencia de ésta técnica.</p>