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This study was conducted at Sugarcane Research Centre, Guneid, (Latitude 15° N, longitude 33° E) in 2008/2009 cropping season. Currently, sugarcane contributes substantially to the national economy in Sudan. The aim was to estimate the amounts of losses (field and factory) incurred on sugarcane by the effects of smut disease of sugarcane caused by Ustilago scitaminea (Syd.). From some selected sugarcane genotypes, replicated cane stalk samples were taken from each of three cane categories: whip-bearing canes from diseased stools (WBC-DS), seemingly healthy looking canes from diseased stools (AHC-DS), and healthy canes from healthy stools (HC-HS). In comparison to healthy canes, brix, sucrose content (pol %), estimated recoverable sugar (ERS), and stalk weight all showed substantial reductions of 5%, 4%, 5%, and 40%, respectively. The fibre content of whip bearing cane stalks was 7% than that of HC-HS and AHC-DS, which is harmful and responsible for ERS losses. Moisture content and purity were however, found to be unaffected by the disease. Smut disease causes losses in most cane yield parameters in both the field and the factory, according to this report. As a result, cane growers must better control this disease, with the most feasible method being the propagation and use of disease-resistant/tolerant sugarcane genotypes, augmented by crop sanitation to keep inoculum levels down.

Biological control of sugarcane smut (Ustilago scitaminea Syd.) using Trichoderma isolates is one of the untapped potentials in Ethiopian sugarcane plantations. To this end, this study was carried out with the objective to identify potential native Trichoderma isolates for the management of sugarcane smut. A total of 120 soil samples were collected from Kesem, Metehara, and Wonji sugarcane plantation fields. Consequently, 21 Trichoderma isolates were recovered from the samples, and in-vitro antagonist study of Trichoderma isolates against U. scitaminea was done using dual culture technique on fresh PDA. Among the native isolates, 12 of them revealed a pathogen suppression potential of >90% at 7 days after inoculation and most of them had higher pathogen suppression than the commercial isolate. However, five of the isolates were selected as potential candidates based on distinct suppression features, growth rate, and antagonistic performance. Identification of the five effective Trichoderma isolates (WI4-27, MKI2-k17, MI3-m33, WI12-25, and MKI3) was done based on macroscopic and microscopic characteristics. Thus, the isolates were identified as T. harzianum, T. asperellum, T. viride, T. viride, and T. harzianum, respectively. Accordingly, these isolates could be used as one component of integrated smut management practices once a study on compatibility with fungicides, in-vivo efficacy test against smut, and substrate selection for mass production of the isolates were commenced.

Sugarcane smut, caused by Ustilago scitaminea Syd., is one of the most severe fungal diseases affecting sugarcane productivity, and all producing countries have developed protocols for the protection and control of this disease [1,2], also a significant decrease in sucrose content.

El presente trabajo se llevó efecto en el laboratorio de Fitopatología pertenecientes al centro de investigaciones de la universidad central de las Villas en el periodo comprendido de noviembre de 1993 a mayo de 1994. en el mismo se estudió el posible biocontrol de Trichoderma spp y gliocladium spp sobre ele carbón de caña de azúcar (Ustilago scitaminea) en condiciones de laboratorio y se obtuvo que ambos hongos ejercen biocontrol sobre el fitopatógeno Abstract : The present work was made in the laboratory of phytopathology of Agricultura reserch center (ARC) of central university of las villas in the period november 1993 to may 1994. the possible biocontrol of Trichoderma spp and Gliocladium above Ustilago scitaminea was studied in laboraory conditions. It was demostrated that U. scitaminea was controled by Trichoerma spp and Gliocladium spp.

Different inoculation techniques viz. inoculation of sets by dipping in spore suspension, bud inoculation with hypodermic syringe, bud wrapping by cotton swab dipped in smut suspension and inoculation of underground bud at the time of tillering (end May) were tested to screen against sugarcane smut in the field as well as in the laboratory conditions. In the field, out of the tested inoculation techniques, the maximum disease incidence (60.63%) was observed when buds were inoculated with hypodermic syringe and minimum (8.55%) in inoculation of underground buds at the time of tillering stage. The result showed that inoculation through mechanical injury significantly increase disease incidence but at the same time also affect the bud germination (15.56%). Significant difference in smut incidence was also observed when the inoculation was carried by teliospores and sporidia separately. Key words: Ustilago scitaminea, inoculation technique, screening, resistance, sugarcane.

A species-specific polymerase chain reaction (PCR) assay was developed for rapid and accurate detection of Ustilago scitaminea, the causal agent of sugarcane smut disease. Based on nucleotide differences in the internal transcribed spacer (ITS) sequences of U. scitaminea, a pair of species-specific primers, SL1 (5`-CAGTGCACGAAAGTACCTGTGG-3`) and SR2 (5`-CTAGGGCGGTGTTCAGAAGCAC-3`) was designed by using a panel of fungal and bacterial species as controls. The primers SL1/SR2 specifically amplified a unique PCR product about 530 bp in length from U. scitaminea strains with a detecting sensitivity at 200 fg of the fungal genomic DNA in a 25 μl reaction solution. To increase sensitivity, a nested-PCR protocol was further established, which used ITS4/ITS5 as the first-round primers followed by the primer pair SL1/SR2. This protocol increased the detection sensitivity by 10,000-fold compared to the PCR method and could detect the fungal DNA as low as 20 ag. The nested-PCR detected U. scitaminea from young sugarcane leaves with no visible smut disease symptoms. The findings from this study provide a sensitive and reliable technique for the early detection of U. scitaminea, which would be useful for sugarcane quarantine and production of germ-free seedcanes.Keywords: Sugarcane, Ustilago scitaminea, nested-polymerase chain reaction (PCR), molecular detection

Whip smut caused by (Ustilago scitaminea) is an important fungal disease, which is widely distributed all over the world causing huge losses in sugarcane crop. Sugarcane crop basically required humid and hot climate for its development which is also favorable for the different diseases in sugarcane. Epidemiological factors play an important role for the development and the management of different diseases. They are also used as disease prediction models. Epidemiological factors are very important for the development and spread of pathogen causing smut of sugarcane. Out of fifteen promising varieties/ lines, eight were found resistant (S2006-US-469, S2006- US-272, S2005-US-54, S2008-AUS-130, S2006-US-658, S2008-AUS-190, S2008-AUS-107, S2009-SA-169), six were moderately susceptible(S2008-M-34, S2008-AUS-133, S2003-US-127, S2003-US-704, S2008-Fd-19, S2008- AUS-87) and one (S2003-US-618 had susceptible reaction against the disease. There was positive correlation of relative humidity with disease incidence and negative correlation of maximum and minimum temperature with disease incidence.

Sugarcane smut disease, caused by Ustilago scitaminea Syd. is universal in distribution being important in every sugarcane producing country including Egypt. The best control measure is the use of resistant cultivars developed by the useual breeding programmes or less common physical treatments as irradiation. In the present study, doses of Gama radiation (0.5, 1, 2, 3 kr) were used to induce mutagenesis in sugarcane buds of the commercial cultivar GT54-9. The normal and transformed percentage of smutted stools of GT54-9 mutants (257mutants) artificially inoculated (dipping and injection inoculation) with smut spores for 3 seasons were field evaluated. The mutants were grouped into 5 groups according to the transformed percentage of infection i.e, group 1 (0 -1%, 38 mutants), group 2 (>1-5%, 29 mutants), group 3 (>5-20%, 71 mutants), group 4 (>20-40%, 65 mutants), group 5 (>40%, 55 mutants). The untreated mother cultivar was placed in group 3 (5-20% infection). The results revealed the importance of direct mutagenic treatment and selection for improvement of commercial sugarcane varieties in Egypt.

Smut disease of sugarcane, caused by the fungus Ustilago scitaminea Sydow, can cause considerable yield losses and reductions in cane quality. To investigate the reactions of the seedlings to smut, three different inoculation methods were employed. Data on number of smut whips per stool, disease incidents per population and number of tillers per plot were recorded and analysed. Results showed that screening for smut resistance at the first stage of selection to assess seedling reaction to smut is possible. The wound paste method of inoculation gave better results than the other techniques evaluated.

The basidiomycete Ustilago scitaminea Sydow, which causes sugarcane smut disease, has been spreading throughout Africa and America since the 1940s. The genetic diversity and structure of different populations of this fungus worldwide was investigated using microsatellites. A total of 142 single-teliospore were isolated from 77 distinct whips (sori) collected in 15 countries worldwide. Mycelium culture derived from on generation of selfing of these single teliospores were analysed for their polymorphisms at 17 microsatellite loci. All these strains but one were homozygous at all loci, indicating that selfing is likely the predominant reproductive mode of U. scitaminea. The genetic diversity of either American or African U. scitaminea populations was found to be extremely low and all strains belong to a single lineage. This lineage was also found in some populations of Asia, where most U. scitaminea genetic diversity was detected, suggesting that this fungal species originated from this region. The strong founder effect observed in U. scitaminea African and American populations suggests that the fungus migrated from Asia to other continents on rare occasions through movement of infected plant material. © 2006 Elsevier Inc. All rights reserved.

Um período de incubação de cinco dias significa, no contexto da epidemiologia de doenças de plantas, que as infecções que deram origem aos sintomas visualizados no tempo t ocorreram no tempo t-5. Há um grupo de doenças, no entanto, que se comporta de modo diferente, isto é, o momento da infecção não pode ser inferido a partir da visualização dos sintomas. Esse grupo de doenças pode ser dividido, para fins didáticos, em função do órgão da planta que exibe os sintomas: (i) brotações jovens; (ii) perfilhos jovens; (iii) frutos recém-amadurecidos. Nesses três subgrupos, a expressão dos sintomas é função do estádio fenológico do órgão afetado e tem pouca relação com o momento da infecção. Para essas doenças, maior ênfase é recomendada para estudos que visem a identificação da época mais provável de ocorrência da infecção, em detrimento do simples acompanhamento da expressão dos sintomas. Exemplos são apresentados para cada subgrupo e o modelo de crescimento monomolecular é sugerido como o que melhor descreve o progresso da doença em função do tempo para o grupo como um todo. In botanical epidemiology, an incubation period of five days means that infections originating symptoms that can be visualized at time t have occurred at time t-5. Since not all diseases follow this rule, their time of infection cannot be derived from the time of symptom appearance. These diseases are grouped according to the plant organ in which symptoms appear: (i) young flushes/shoots; (ii) young tillers; (iii) fully developed fruits. In all these subgroups symptom expression is a function of the phenological stage of the plant organ and has little relation to the time of infection. For these diseases, studies to determine the infection period should be emphasized, rather than the trivial monitoring of disease expression. Examples are given for each subgroup and the monomolecular growth is proposed as the best model to describe the disease progress curve for the whole group.

Sugarcane smut (Ustilago scitaminea) is the most prevalent and serious disease of sugarcane in Nigeria. Efforts made so far to check its destructive effects on the growing sugarcane industry have centred on use of single-strategy controls. These are pre-plant heat therapy of planting setts; pre-plant fungicidal dips of planting setts and screening of sugarcane clones for identification of resistant varieties against the pathogen. Current awareness suggests that these singlestrategy controls may not be adequate for many sugarcane pests and diseases including smut. This paper highlights some basic considerations to be put in place for the attainment of the IPM strategy for smut management. Also highlighted are known options offered by genetic engineering that could be exploited in combination with numerous other single-strategy controls in the conceived IPM model for sugarcane smut management in Nigeria.

The polymorphism and similarity relationships among 35 mating-type isolates of Ustilago scitaminea collected from Southern China were determined with random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) analyses. These fungal isolates were collected from 16 sugarcane cultivars including F134 that is resistant to the physiological race 1 but susceptible to the race 2 of U. scitaminea, and N: Co376 that is immune to both races 1 and 2. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis revealed that the U. scitaminea isolates could be divided into 2 groups with a coefficient of 0.74. The first group comprises two isolates collected from the sugarcane cultivar F134, while the remaining 33 isolates were clustered into the second group. The second group was further divided into two subgroups with most of the isolates from Guangdong Province which clustered in the same subgroup, and all the isolates from Guangxi and Yunnan Provinces were clustered in another subgroup. Given that the member of the second group could infect the cultivar N:Co376, which is immune to the races 1 and 2, our results suggest that majority of U. scitaminea in sugarcane-producing regions of Southern China may belong to or genetically similar to race 3. Key words: Ustilago scitaminea , sugarcane, inter-simple sequence repeat (ISSR), random amplified polymorphic deoxyribonucleic acid (DNA) (RAPD), genetic diversity.

Differential gene expression in sugarcane during sugarcane-Ustilago scitamineainteraction was conducted in a smut-resistant genotype. Using cDNA-AFLP along with silver staining, a total of 136 transcript-derived fragments (TDFs) were found to be differentially expressed in response to challenge byU. scitaminea. Forty TDFs, 34 newly induced plus six with obvious upregulated expression after infection, were sequenced and validated by RT-PCR analysis. These results demonstrated that the expression of 37 out of these TDFs in RT-PCR analysis was consistent with that in cDNA-AFLP analysis. Based on BlastX in NCBI, 28 TDFs were assumed to function in sugarcane underU. scitamineastress. Analysis of expression profile of three TDFs revealed that they responded differently after infection withU. scitaminea, and the transcription was significantly enhanced. The response of two TDFs, SUC06 and SUC09, occurred before that of SUC10. This study enriches our knowledge of the molecular basis for sugarcane response toU. scitamineainfection.

Lors de visite à Bambey, je n'ai trouvé aucun dysfonctionnement de la quarantaine. Actuellement, la plupart des diagnostics de maladies peuvent y être réalisés. J'ai émis quelques recommandations pour compléter et améliorer les équipements de la quarantaine. Les observations visuelles des variétés de canne à sucre en serre n'ont pas révélé de maladie d'origine parasitaire. Sur le casier de Richard Toll, l'enquête réalisée confirme la présence de l'agent causal de la maladie de la feuille jaune sur une parcelle cultivée avec la variété SP70 3370. D'autres enquêtes sont à envisager, car pour le moment, il n'est pas possible de conclure sur le niveau sanitaire de l'ensemble du périmètre pour cette maladie. Le charbon est toujours présent à Richard Toll. Le manque de données chiffrées, et ce depuis quelques années, ne permettent pas de statuer sur l'évolution de cette maladie.

Le charbon est une maladie présente dans toutes les zones de culture de la canne à sucre, à l'exception de la Papouasie-Nouvelle-Guinée, qui est pourtant le berceau de l'espèce ancestrale domestiquée, Saccharum officinarum. Des études permettent désormais de mieux cerner la diversité génétique de ce champignon et le déterminisme génétique de la résistance de la canne.

Le présent rapport expose les protocoles expérimentaux ainsi que l'interprétation des résultats des essais suivis en 2008/2009. Ces travaux ont été réalisés conjointement par les équipes de eRcane et du CIRAD. Les essais gommose et échaudure ont été plantés et son entretenus par les équipes de eRcane à la Mare sous la responsabilité de J. Bernard. Les souches bactériennes sont maintenues, évaluées, et multipliées par M. Payet. L'inoculation des essais et la lecture des symptômes sont réalisées par les équipes de eRcane (A.Thong Chane, C,Boisbineuf, F. Poiny, B. Sinama, et P. Dabreton) et du CIRAD (M. Payet, H. Télismart, I.Promi, C. calmes et C. Lallemand). L'essai charbon est entretenu par les équipes de eRcane au Gol sous la responsabilité de JP Dioflar. La plantation à été réalisée par les équipes de eRcane et du CIRAD. La collecte des spores de charbon, l'inoculation et la lecture des symptômes ont été faites par I.Promi, H. Télismart et C. Lallemand. (résumé d'auteur)

Ustilago scitaminea Sydow, which causes sugarcane smut disease, has been spreading throughout Africa and America since the 1950s. The objectives of the present study were (1) to confirm and further describe the global population structure of U. scitaminea on the basis of a larger number of isolates and (2) to infer its reproduction system. Microsatellite markers, that present the advantage of being highly polymorphic, PCR-based, reproducible and codominant, were therefore developed for U. scitaminea and used to analyse a sample of single-teliospore isolates from various sugarcane-producing countries around the world. We surveyed 142 single-spore isolates of Ustilago scitaminea for genetic diversity. The fungal samples were teliospores from 77 single whips (sori) collected on various cultivars and at different locations in 15 sugarcane-growing countries throughout the world. The overall genetic structure of this fungus was investigated using 17 polymorphic microsattelite loci. All isolates but one were homozygous for all loci, indicating that selfing could be the highly preferential predominant reproductive mode of U. scitaminea. In America and Africa, genetic diversity was found to be extremely low and all isolates belonged to a single inbred lineage. This inbred lineage was also found in some parts of the Asian continent where most U. scitaminea genetic diversity was detected. These observations support the hypothesis that the fungus originated in Asia. The strong founder effect observed in the global genetic structure of U. scitaminea suggests that the fungus migrated from Asia to other continents on rare occasions. (Texte intégral)

Sugarcane smut, caused by Ustilago scitaminea Syd., is present in all sugarcane growing areas with the exception o f Papua New Guinea, Fiji and the eastern side of Australia. Breeding for smut resistance is efficient because this trait is fairly heritable but it requires complicated screenings. Moreover, the genetic control o f smut resistance is still unknown. With the objective to identify the mendelian factors involved in sugarcane resistance to smut, two strategies have been implemented (1) QTL mapping in a bi-parental progeny derived from a cross between a resistant cultivar 'R 570' and a highly susceptible clone 'MQ 76/53', evaluated in Reunion island for resistance to smut (2) Association study in a population of cultivars, evaluated in Burkina Faso for resistance to smut. First, the worldwide genetic structure of U. scitaminea was investigated. A total of 142 singleteliospore isolates from 15 countries worldwide were analysed using 17 polymorphic microsatellite loci. All isolates but one were homozygous for all loci, indicating that selfing is the highly preferential reproductive mode of U. scitaminea. In America and Africa, genetic diversity was found to be extremely low and all isolates belonged to a single inbred lineage. This inbred lineage was also found in some parts of the Asian continent where most U. scitaminea genetic diversity was detected. These observations support the hypothesis that the fungus originated in Asia. Thus, the bi-parental population and the population of cultivars used to study the genetic determinism of smut resistance have been evaluated towards isolates from the worldwide lineage. The genetic maps of the two parents o f the bi-parental progeny, 'R 570' and 'MQ 76/53', were constructed using a population o f 198 progeny. A total o f 1666 polymorphic markers were produced using 37 AFLP primer pairs combinations, 46 SSRs and 9 RFLP probes. Linkage analysis allowed the construction of 86 cosegregation groups for 'R 570' and 105 cosegregation groups for 'MQ 76/53' encompassing 424 and 536 single dose markers respectively. The cumulative length of 'R 570' map was 3144 cM. The cumulative length of 'MQ 76/53' map was 4329 cM. On 'MQ 76/53' map, a gene controlling the red colour of the stalks was identified at 6.5 cM of an AFLP marker and a new brown rust resistance gene was identified at 23.1 cM o f an AFLP marker. The structure of linkage disequilibrium in the population o f cultivars was investigated using 1626 AFLP markers, among which 408 have known positions on 'R 570' genetic map. Thus, it was possible to study the relationship between genetic distances and statistical associations between markers in the population of cultivars, calculated using the Fisher exact test. This analysis confirmed that linkage disequilibrium in sugarcane extends over distances o f tenth of centiMorgans but drops sharply for distances over 5 cM. This order of magnitude indicates that genome-wide association studies are achievable in sugarcane. Field trials and greenhouse trials using different inoculation methods were conducted in order to characterize the resistance o f the 198 progeny clones from the bi-parental population. The distribution of disease scores observed in all those trials were highly unbalanced toward the resistant parent indicating the segregation o f multiple dominant resistance factors. A QTL detection was performed using the 1666 available markers allowing the identification of a few genomic zones with small effects. Besides, the association study performed in the population of cultivars (constituted o f two subpopulation, one highly susceptible to smut and the other highly resistant to smut) revealed interesting haplotypes associated with resistance. Two QTLs have been detected through both approaches. The progress obtained toward a better understanding o f the genetic determinism of sugarcane resistance to smut are modest. The potential of association studies in sugarcane appeared interesting although much more markers would have to be used to make the most of it.

A Quantitative Trait Locus (QTL) mapping study is under way to analyse the genetic determinism underlying sugarcane smut resistance. A total of 1295 polymorphic AFLP markers have been generated on a population of 200 individuals derived from a cross between R 570 (resistant) and MQ 76/53 (highly susceptible). This population is under evaluation for its resistance to smut in the field over three successive crop cycles and in two different locations on Reunion island. Inoculation was performed by dipping three-bud cuttings in a spore suspension, and susceptible clones were regularly interspersed in the field to trigger the epidemy. Different inoculation methods were also compared in greenhouse trials. The bud puncture method appeared the most efficient and will be used for further greenhouse evaluations of the progeny. Detection of marker-trait associations has been performed and so far has indicated a complex determinism for smut resistance. Many markers are involved with little effects. Nevertheless, among other traits that were looked at, two putative major genes originating from MQ 76/53 have been tagged: a gene involved in the red color of the internode and a rust resistance gene. Locus specific markers, SSR markers from sugarcane and maize and sequences differentially expressed in response to challenge by smut (provided by the South African Sugar Association Experiment Station), will be mapped. This should help explain the genetic variation in smut resistance observed in the trials.

L'historique de l'aaparition du charbon de la canne à sucre causé par le champignon basidiomycète Ustilago scitaminea Sydow est decrite avec les symptomes de la maladie, les conditions favorables au développement, les hôtes naturels, l'importance économique, les méthodes de lutte et les conditions de transmission