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BACKGROUND: Herbivory risk is mediated by plant traits related to nutrition and defense that can vary within a species by genotype and age. Prior herbivore damage accrued by a plant can also interact with these traits to alter future herbivory potential by changing plant quantity or quality. Sugarcane (Saccharum spp.) is a perennial crop where aboveground biomass is harvested annually and with varieties differing in nutrition and defenses, making it conducive to evaluating varietal resistance mechanisms. Using data from 16 sugarcane varieties and 28 years, we assessed damage from the primary pest in Louisiana, the sugarcane borer (Diatraea saccharalis, SCB), relative to variety, crop year (ratoon), plant traits, and incidence of prior herbivory. RESULTS: SCB damage differed among varieties but not crop year, mostly following previously established classifications of SCB resistance, and correlated with select nutritional and defense traits. Within a crop year, the probability of SCB damage increased with prior conspecific damage on the same stalk. However, the strength of this prior damage effect did not match known resistance patterns but still differed with variety. CONCLUSIONS: Interactions of plant variety, traits, and prior pest damage but not age impacted sugarcane borer risk. Borer damage was associated with nutritional traits of fiber and sugar content, but not consistently with defensive traits like high stalk wax or hair density, indicating there may be additional resistance traits or indirect impacts of these traits on predators. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Sugarcane yellow leaf disease (YLD) caused by sugarcane yellow leaf virus (ScYLV) is a major threat for the sugarcane industry worldwide, and the aphid Melanaphis sacchari is its main vector. Breeding programs in Brazil have provided cultivars with intermediate resistance to ScYLV, whereas the incidence of ScYLV has been underestimated partly due to the complexity of YLD symptom expression and identification. Here, we evaluated YLD symptoms in a field assay using eight sugarcane genotypes comprising six well-established commercial high-sucrose cultivars, one biomass yield cultivar, and a susceptible reference under greenhouse conditions, along with estimation of virus titer through RT-qPCR from leaf samples. Additionally, a free-choice bioassay was used to determine the number of aphids feeding on the SCYLV-infected cultivars. Most of the cultivars showed some degree of resistance to YLD, while also revealing positive RT-qPCR results for ScYLV and virus titers with non-significant correlation with YLD severity. The cultivars IACSP01-5503 and IACBIO-266 were similar in terms of aphid preference and ScYLV resistance traits, whereas the least preferred cultivar by M. sacchari, IACSP96-7569, showed intermediate symptoms but similar virus titer to the susceptible reference, SP71-6163. We conclude that current genetic resistance incorporated into sugarcane commercial cultivars does not effectively prevent the spread of ScYLV by its main aphid vector. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anatomical adaptation is an important feature that allows plants to mitigate drought stress. A comparative leaf anatomy of two drought-tolerant sugarcane cultivars, KKU-1999-02 and KKU-1999-03, was studied in early drought stress between 30 and 90 days after planting using peeling and freehand sectioning methods. KKU-1999-02 and KKU-1999-03 showed different anatomical adaptation features, such as increase in cuticle thickness, bulliform cell size, vascular bundle, and stomatal density, and decreases in leaf thickness and stomatal size. KKU-1999-02 showed more remarkable anatomical changes than KKU-1999-03. The results provide important information that can be applied in combination with other agronomic traits in sugarcane breeding programs to expand the adaptation devices of tolerant cultivars under preliminary drought stress. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the progress in each of the stages of the selection program of sugarcane varieties that has been carried out at the Colegio de Postgraduados Campus Córdoba (Mexico) since 2009. Design/methodology/approach: The breeding program employed the methodology developed by the Institute for the Improvement of Sugar Production (Instituto para el Mejoramiento de la Producción de Azúcar, IMPA). For the varietal description, we employed the protocol of the International Union for the Protection of New Varieties of Plants (UPOV). Results: In 2009, the Colegio de Postgraduados Campus Córdoba started the varietal selection program with more than six thousand hybrids from 40 crosses, from which 4422 materials were selected after they showed resistance to the sugarcane mosaic virus. From the 4422 materials in the Seedling phase, 352 clones were selected and evaluated in the Furrow phase, selecting 57 varieties for the Plot phase. From those 57 varieties, 35 were selected in the Adaptability testing phase and 27 in the following Agroindustrial evaluation phase. Some of these 27 varieties show yields higher than 100 t ha-1, more than 18 °Brix in juices, and good adaptability to different environments. Study limitations/implications: The current challenges of the breeding program are environmental due to climate change, economical due to the global recession that affects our country with budget cuts, and sociopolitical as a result of the organizational structure of national the sugarcane sector. Findings/conclusions: This variety breeding and selection program started with 6000 individuals from 40 crosses, of which to date there are 27 in advanced stages of selection, with the possibility of adaptation and good yields for the area of influence of the Campus Córdoba. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the growth and yield of the sugarcane plant cultivars, and their correlation to soil mechanical penetration resistance in a Dystroferric Red Oxisol submitted to reduced tillage and, no-tillage systems. Eight sugarcane plant cultivars (RB965902, RB985476, RB966928, RB855156, RB975201, RB975242, RB036066 and RB855536) were in each soil preparation system, and the trial was conducted in a completely randomized design and eight treatments and four replications. The trial evaluated: number of tillers per meter, stalks height and diameter, and stalks yield and sugar content. Additionally, were evaluated the soil mechanical penetration resistance (PR) and soil moisture. The highest rates of daily elongation, yield of stalks and sugar content were observed under no - tillage, due to the lower soil mechanical penetration resistance and higher soil moisture. The cultivar RB966928 presented higher values for growth, yield of stalks and sugar content, while RB855536 and the medium to late maturity cultivars RB975201, RB975242, RB036066, which had either a lower stalk growth rate or presented lower number at the end of the cycle in both soil tillage. [ABSTRACT FROM AUTHOR]

Highlights • Mean stalk dry mass in Guadalupe, Brazil, at 8, 11.5 and 15 months was, respectively, 40, 51 and 70 t/ha. • The high sugarcane yields achieved in Guadalupe were explained mainly by high, but not excessive, air temperatures. • Substantial changes were required to enable APSIM-Sugar to simulate light interception and yield for Brazilian genotype. • A new feature to deal with growth slowdown was proposed. • Simulation studies in environments where stalk dry mass is likely to exceed 40 t/ha should include the new RGP. Abstract Sugarcane in field plot experiments in tropical Brazil (Guadalupe, Piauí State, 6.6 °S), produced very high yields under non-limiting water and nutrients. Mean stalk dry mass at 8, 11.5 and 15 months were 40, 51 and 70 t/ha respectively for six varieties and six planting dates. These yields were explained by high but not excessive temperatures allowing the canopy to close after 73 days on average. Substantial changes were required to enable the APSIM-Sugar model to simulate canopy and yield gain processes in Brazilian genotypes for the purpose of optimising variety, planting and harvest date options. A new modelling feature was proposed to deal with the observed growth slowdown when crop was about 7–8 months old and dry mass yields higher than 40 t/ha. All new parameters and features were validated with independent experiments as well as with the original dataset used for developing APSIM-Sugar. Future studies involving irrigation, yield gap analysis and climate change in environments where high yields are expected, should consider these modifications. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Sugarcane (Saccharum spp.) is the main raw material for sugar and ethanol production. Among the abiotic stress, drought is the main one that negatively impact sugarcane yield. Although gene expression analysis through quantitative PCR (qPCR) has increased our knowledge about biological processes related to drought, gene network that mediates sugarcane responses to water deficit remains elusive. In such scenario, validation of reference gene is a major requirement for successful analyzes involving qPCR. Results: In this study, candidate genes were tested for their suitable as reference genes for qPCR analyses in two sugarcane cultivars with varying drought tolerance. Eight candidate reference genes were evaluated in leaves sampled in plants subjected to water deficit in both field and greenhouse conditions. In addition, five genes were evaluated in shoot roots of plants subjected to water deficit by adding PEG8000 to the nutrient solution. NormFinder and Ref-Finder algorithms were used to identify the most stable gene(s) among genotypes and under different experimental conditions. Both algorithms revealed that in leaf samples, UBQ1 and GAPDH genes were more suitable as reference genes, whereas GAPDH was the best reference one in shoot roots. Conclusion: Reference genes suitable for sugarcane under water deficit were identified, which would lead to a more accurate and reliable analysis of qPCR. Thus, results obtained in this study may guide future research on gene expression in sugarcane under varying water conditions. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify superior parents for crosses and the best families to breed new clones of energy cane. The best-performing parents were RB867515, RB93509, KRAKATAU, IM76-228, IM76-229, and US85- 1008. The heritability (0.59 - 0.85)and accuracy values (0.76 - 0.92) for the traits tons of cane per hectare, fiber, and sucrose content indicate high correlation between the predicted genotypic means and observed values, enabling efficient selection of the best cane energy families. The extensive genetic variation detected and the presence of promising seedlings in the selected segregating population indicate the possibility of using new crosses in some clones and even in future commercial plantings. It was possible to identify the best parents involved in the evaluated crosses, and to select, in the best families, seedlings with a high fiber and good sucrose content, seedlings with high fiber and low sugar content, as well as seedlings with the same fiber and sucrose contents as the current cultivars. [ABSTRACT FROM AUTHOR]

The sugarcane varieties RB975201 and RB975242 were developed and released for harvest at the end of the season (late maturation) in the Central- South region of Brazil. In specific environments, these varieties were compared with commercial standards in sugar yield per area. They are resistant to major sugarcane diseases and present the Bru1 gene of resistance to brown rust. [ABSTRACT FROM AUTHOR]

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The Mexican rice borer, Eoreuma loftini (Dyar), is a major pest of sugarcane (hybrids of Saccharum spp.) in Louisiana and Texas. Resistance to E. loftini was evaluated in 51 commercial and experimental cultivars of sugarcane, energycane (hybrids of Saccharum spp.), and sorghum [Sorghum bicolor (L.) Moench and hybrids of Sorghum spp.] in four replicated small plot field experiments from 2009 to 2012. A relative resistance ratio was developed to compare levels of susceptibility among cultivars based on the percentage of bored internodes and survival to adulthood. This index was able to separate cultivars into five resistance categories and provides a new method for comparing levels of resistance among cultivars. E. loftini pest pressure in 2009 was among the highest recorded with injury ranging from 55 to 88% bored internodes. Commercial sugarcane cultivar HoCP 85-845 was identified as resistant in three of four experiments, whereas HoCP 04-838 was identified as susceptible in all experiments. Of the five sugarcane cultivars in commercial production in the Rio Grande Valley of Texas, only TCP 87-3388 was categorized as resistant. Of the cultivars with potential for bioenergy production, all of the energycane cultivars demonstrated higher levels of resistance than high-biomass and sweet sorghum cultivars. Continued evaluation of cultivar resistance to E. loftini is important to development of effective integrated pest management strategies for this pest. [ABSTRACT FROM AUTHOR]

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Considering that from 2014 will no longer be allowed fires in São Paulo sugarcane, soybean growers who lease these areas should adapt to the no-tillage system in order to enjoy the agronomic benefits that the straw sugarcane provides. The study was conducted in Araçatuba, SP, during crop year 2011/12, and Araçatuba, SP, Brazil and Américo de Campos, SP, Brazil in 2012/13 and aimed to evaluate the influence of nitrogen on the yield of different cultivars soybean grown no-till on straw sugarcane, and the influence on the degradation of straw. We used a randomized block design in split-bands split plot with three replications. In the crop year 2011/12 we used a 5 x 2 factorial design, with five soybean cultivars: P 98Y11 RR, RR CD 219, M-Soy 7908 RR, BRS Valiosa and RR SYN 9078 RR, and two nitrogen levels: 0 and 45 kg ha-1 in the form of urea. In the crop year 2012/13, the study was conducted on the cultivar M-Soy 7908 RR in Araçatuba, SP, Brazil and on the cultivar SYN 9078 RR in Américo de Campos, SP, Brazil using four treatments (nitrogen): 0, 30, 45 and 60 kg ha-1, in the form of ammonium nitrate (30 and 60 kg ha-1) and urea (45 kg ha-1). It was found that the use of urea and ammonium nitrate did not influence the straw decomposition of cane sugar and did not promote significant increases in grain yield soybean of the cultivars evaluated. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate sugarcane genotypes for the trait tons of sugar per hectare (TSH), stratifying five production environments in the state of Paraná. The performance of 20 genotypes and 2 standard cultivars was analyzed in three consecutive growing seasons by the statistical methods AMMI and GGE Biplot. The GGE Biplot grouped the locations into two megaenvironments and indicated the best-performing genotypes for each one, facilitating the selection of superior genotypes. Another advantage of GGEBiplot is the definition of an ideal genotype (G) and environment (E), serving as reference for the evaluation of genotypes and choice of environments with greater GE interaction. Both models indicated RB006970, RB855156 and RB855453 as the genotypes with highest TSH and São Pedro do Ivai as the environment with the greatest GE interaction. Both approaches explained a high percentage of the sum of squares, with a slight advantage of AMMI over GGE Biplot analysis. [ABSTRACT FROM AUTHOR]

Copyright of BIOAGRO is the property of Revista BIOAGRO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The sugarcane cultivar RB937570 is early to medium maturing. It should be grown preferably on medium texture soils with medium to high fertility. In central-southeastern Brazil, RB937570 should be harvested between May and August. It is tolerant to the major economically relevant crop diseases, has a good shoot development after mechanical harvesting and high sucrose yields. [ABSTRACT FROM AUTHOR]

Sugarcane is an important international commodity as a valuable agricultural crop especially in tropical and subtropical countries. Two bulked DNA used to screen polymorphic primers from commercial hybrids (varieties) with moderately resistant and highly susceptible to red rot disease. Among 145 simple sequence repeat and unigene primers screened, 37 (25%) were found to be highly robust and polymorphic with Polymorphism Information Content values ranging from 0.50 to 1.00 with the mean value of 0.82. Among these microsatellites, twenty one were used in the study of genetic relationships and marker identification in sugarcane varieties for red rot resistance. A total of 105 polymorphic DNA bands were identified, with their fragment size ranging from 54 to 1,280 bp. Jaccard's similarity coefficient value recorded between closely related hybrids was 0.986 while lowest coefficient value of 0.341 was detected with distantly related hybrids. The average similarity coefficient among these hybrids was 0.663. Cluster analysis resulted in a dendrogram with two major clusters separating the moderately resistant varieties from highly susceptible varieties. Three group specific fragments amplified by unigene Saccharum microsatellite primers viz; two markers UGSM316 and UGSM316 were closely associated with moderately resistant varieties by appearing bands in this region but the bands were absent in highly susceptible varieties. Similarly UGSM316 marker was tightly linked with highly susceptible varieties by amplifying uniformly in sugarcane varieties showing highly susceptible reaction to red rot but it was absent in moderately resistant varietal groups. Validation of red rot resistance/susceptibility associated markers on a group of different mapping populations for red rot resistant/susceptible traits is in progress. [ABSTRACT FROM AUTHOR]

This work was undertaken to evaluate the relationship between sugarcane (Saccharum spp.) culms basal cutting height and harvest period and their effects on bromatologic characteristics of two sugarcane cultivars under ratoon cycle. The research was carried out in the region of Jaú, SP, Brazil. The experiment was arranged in randomized blocks, in a 2 x 3 x 3 factorial design corresponding to two genotypes (IAC86-2480 and RB72454), three cutting heights (0, 10 and 20 cm above soil level) and three harvest periods (May, July and September 2006) with four replications. The results of the interaction between cultivar x cutting height x harvest period showed that sugarcane cultivars had better forage quality in terms of dry matter and crude protein by the cutting height at 0 and 10 cm and harvest period of the culms in September, and in terms of mineral matter, neutral detergent fiber, acid detergent fiber and lignin when the harvest season was in May. The cultivar IAC86-2480 has better chemical quality as forage, since the cutting height of the stalks is adjusted to the period of harvest. [ABSTRACT FROM AUTHOR]

The aim of this study was to estimate the variability and the genetic correlations between clones RB and the varieties of cane sugar. The experimental works were carried out during the 2005/2006 agricultural year in Central Olho D'Água Sugar Mill (North Forest of Pernambuco, Brazil) and Trapiche (South Coast of Pernambuco, Brazil). The experimental design was made in randomized blocks with four blocks and different treatments, one with sixteen genotypes conducted in North Forest, and another with eighteen other genotypes installed on the South Coast. The following characters were defined as production components: average culms number, average culms diameter, average culms weight, average internodes number, average culms height and average leaf area. Results indicated that the genetic variability in genotypes populations and the commercial varieties tested in the North Forest and South Coast of Pernambuco, can be effective in selecting genotypes through leaf area, and culms height and weight; determining characteristics of the production of sugarcane. The number of culms is negatively associated with culms diameter, height and weight, the number of internodes and the leaf area, thus preventing the simultaneous or indirect selection between the characters pairs. [ABSTRACT FROM AUTHOR]

RB966928 is an early to medium maturing sugarcane cultivar and in Central-Southern Brazil it is harvested between April and June; it is recommended for planting in environments with medium to high soil fertility. It stands out with a high ratoon yield and with excellent sprouting in both plant cane and ratoon cane. It is tolerant to the major diseases of economic importance of sugarcane. [ABSTRACT FROM AUTHOR]

This study aimed to compare the efficiency in the selection of genotypes and the quality of the estimates of the variance components and heritability using the augmented block designs (ABD), the duplicated augmented block designs (DABD) and the group of randomized blocks design experiments with common treatments (ERBCT). For comparison, it was imposed a condition that the number of genotypes under selection was greater than the number of units available for experimental designs with repetition. Four scenarios were composed of a combination of different values of heritability and parametric residual coefficient of variation. From the 2400 simulations per scenario the ABD had the highest selection efficiency. The designs with repetition (DABD and ERBCT) had similar selection efficiency between them. It is possible to conclude that not using repetitions, and therefore, evaluating a larger number of genotypes, can bring better results to the plant breeding program. [ABSTRACT FROM AUTHOR]

Many plants grown in soils amended with silicon (Si) display increased levels of resistance to attack by insect herbivores. This study aimed to determine if Si treatment impeded Eldana saccharina Walker (Lepidoptera: Pyralidae) stalk penetration and subsequent damage, as well as borer mass gain, on the node and internode of a susceptible (N11) and a resistant (N33) sugarcane cultivar. Sugarcane [ Saccharum spp. (Poaceae)] cultivars were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si–) calcium silicate. Sugarcane was infested with 2-week-old E. saccharina larvae and harvested at four times, 24, 48, 72, and 96 h after infestation. Silicon-treated plants showed significant increases in Si content compared to controls, and the external rind was significantly harder for Si+ cane than Si– cane. Silicon treatment significantly decreased borer penetration, stalk damage, and larval mass gain. The results are consistent with the hypothesis that Si contributes to sugarcane stalk borer resistance by impeding larval penetration. Silicon appears to contribute to the suppression of E. saccharina directly through reduced larval growth and feeding damage to the crop, and indirectly by delaying stalk penetration, resulting most likely in increased exposure time of young larvae to natural enemies, adverse climatic factors, or control measures that target young larvae (e.g., insecticides). [ABSTRACT FROM AUTHOR]

Extending duration of moderately used 1-day preharvest floods in sugarcane (Saccharum spp.) could improve Florida sugarcane insect control, freeze protection, and soil conservation, and reduce unwanted P discharge. The purpose of this study was to compare the effects of flood duration and month of flood application on theoretical recoverable sucrose (TRS), cane yield, and sucrose yield of four sugarcane cultivars. During the plant-cane and first-ratoon crop cycles, 0-, 10-, or 20-day floods were applied in November or January to lysimeters planted with cultivars CP 72-2086, CP 80-1827, CP 89-2143, and CP 92-1666. Cane and sucrose yields of flooded treatments were at least as much as those of non-flooded controls. These results warrant research to quantify the profitability of preharvest flooding of sugarcane, recognizing that these 10-20 day floods had minimal impact on yields while offering potential economic returns from other agronomic and ecologic benefits. [ABSTRACT FROM PUBLISHER]

Abstract: Sugarcane in an important crop due to the economic value of its products. Physiological characteristics and yield components of sugarcane were studied in three field-grown sugarcane cultivars B 63118, POJ 2878 and Ja 60-5. Three growth stages were identified: formative phase (until 140DAP), grand growth (140–300DAP) and maturity (after 300DAP). Results indicated that cultivars showed contrasting yield mainly after 300DAP. At ripening, the most productive cultivar (Ja 60-5) achieved higher leaf area, an optimum leaf area index for light interception, a high and stable net assimilation rate and an elevated leaf area and biomass duration. In addition, this cultivar showed the higher density and lower area of leaf sieve elements as compared with other, which could influence the high translocation rate (1.85cmmin−1) at 8MAP. The higher efficiency of this process in Ja 60-5 might also be supported by a higher (15–25%) apparent free space of stem parenchyma as compared with POJ 2878 and B 63118. Our results suggest that Ja 60-5 reduced carbon partitioned to foliar respiration which led to a higher partitioning of sucrose to stems evidenced by a higher Pol%. [Copyright &y& Elsevier]

Specific primer pairs were designed to distinguish four genotypes (BRA for Brazil, CUB for Cuba, PER for Peru, and REU for Réunion Island) of Sugarcane yellow leaf virus (SCYLV) by reverse transcription-polymerase chain reaction (RT-PCR). A unique genome fragment was amplified from each genotype, with the exception of genotypes BRA and PER that are phylogenetically relatively close and were designated genotype BRA-PER. These RT-PCR primers were then used to identify the SCYLV genotype(s) present in 18 different sugarcane growing locations in the world, and 245 leaf samples infected by the virus were analyzed. Most samples were infected by only one of the three genotypes, but mixed infections occurred. Genotype BRA-PER was found in all sugarcane growing locations, whereas genotypes CUB and REU were each found in four geographical locations only. Genotypes BRA-PER, CUB, and REU were all three detected in locally bred sugarcane cultivars in Guadeloupe, indicating local transmission of these genotypes. In contrast, only genotypes BRA-PER and CUB were found in locally bred cultivars in Brazil, whereas genotype REU was detected in this country in cultivar R570 imported from Réunion. Similarly, genotypes BRA-PER and REU are both present in Réunion, but genotype BRA-PER has not, as of yet, spread on this island. Presence of several SCYLV genotypes in Brazil, Colombia, Guadeloupe, Mauritius, and Réunion suggests different virus introductions and/or different evolution histories of the virus after its introduction into a new environment. [ABSTRACT FROM AUTHOR]

Three transgenic sugarcane populations produced byAgrobacterium tumefaciensinfection were analysed for the presence of genomic variability. Plants of the original cultivar, plants regenerated without transformation, as well as transformed and untransformed calli were used as control treatments. Amplified fragment length polymorphism (AFLP) of DNA extracted from leaves or calli assessed genomic profiling. The average DNA polymorphism within each population was determined by calculating the polymorphism index, while the extent of genomic dissimilarity among individual plants within transgenic populations was verified in unweighted pair group method using arithmetic averages dendrograms. The results showed that the production of transgenic sugarcane plants byA. tumefaciensinfection is accompanied by limited but detectable genomic changes and that, on average, these occur at the same rate in plant populations carrying different transgenes. Main factors contributing to somaclonal variation in transgenic sugarcane plants have been verified by pre-existing DNA polymorphism into the donor genotype andin vitroculture steps during the transformation procedure. The relevant practical conclusion from this finding is that the AFLP analysis may be effectively used to identify individual transgenic plants with the least genomic deviation from the parental ones. The selected genotype would be conserved as cultivated sugarcane is asexually propagated. [ABSTRACT FROM AUTHOR]

Despite the economical importance of sugar cane, until the present-date no studies have been carried out to determine the correlation of the molecular-based genetic similarity (GS) and the coefficient of parentage (f)-estimates generated for cultivars. A comprehensive knowledge of the amount of genetic diversity in parental cultivars, could improve the effectiveness of breeding programmes. In this study, amplified fragment length polymorphism (AFLP) and pedigree data were used to investigate the genetic relationship in a group of 79 cultivars (interspecific hybrids), used as parents in one of the Brazilian breeding programmes, and four species of Saccharum (Saccharum sinense, Saccharum barberi and two of Saccharum officinarum) . The objectives of this study were to assess the level of genetic similarity among the sugar-cane cultivars and to investigate the correlation between the AFLP-based GSand f, based on pedigree information. Twenty one primer combinations were used to obtain the AFLP molecular markers, generating a total of 2,331 bands, of which 1,121 were polymorphic, with a polymorphism rate, on average, of 50% per primer combination. GSs were determined using Jaccard’s similarity coefficient, and a final dendrogram was constructed using an unweighted pair-group method using arithmetic average (UPGMA). AFLP-based GS ranged from 0.28 to 0.89, with a mean of 0.47, whereas f ranged from 0 to 0.503, with a mean of 0.057. Cluster analysis using GS divided the genotypes into related subgroups suggesting that there is important genetic relationship among the cultivars. AFLP-based GS and f were significantly correlated (r = 0.42, P < 0.001), thus the significance of this r value suggests that the AFLP data may help to more-accurately quantify the degree of relationship among sugar-cane cultivars. [ABSTRACT FROM AUTHOR]

Traditional sugarcane breeding seeks for high sucrose content. However, with the increasing demand for renewable energy sources, there has been a shift in desired traits for sugarcane as an energy crop. Energy cane is a cultivar developed from Saccharum spp. with high fiber, higher biomass productivity and resilience, having great potential as a bioenergy feedstock. This work analyzed biomass content and chemical composition of two energy cane clones (VG1126 and VIGNIS 3) and one of its progenitors, S. spontaneum (VG spo), throughout distinct stages of internode development. VG1126 had a fiber and sucrose content closer to the ancestral, showing 24% more fiber than VIGNIS 3, being more suitable for industrial lignocellulose applications. Both energy canes showed an increase in lignin content, S/G ratio and p CA along internode development. Ancestral cane, however, showed similar composition across culm development, suggesting that it completes vegetative growth faster than energy cane. Although the three crops have different fiber contentconte, sucrose content, and morphology, their overall biomass composition (lignin, cell wall sugars, and hydroxycinnamates) was similar. These results represent a useful model to follow chemical cell wall composition during vegetative cell development and are expected to help breeding energy cane cultivars programs to use in biorefineries. • S. spontaneum has high fiber and low sucrose content, and it is used as a parental line to energy cane cultivars. • S. s pontaneum lignin S/G unit ratio is distinct among cultivars of the same species. • Distinct sugarcane crops have different fiber, sucrose, and morphology, but similar biomass composition. • The internodes from the top to the base of the culm revealed progressive maturation stages. • Sampling culm across the stages of development was a useful system to follow cell wall composition in energy cane varieties. [ABSTRACT FROM AUTHOR]

Red stripe disease in sugarcane caused by Acidovorax avenae subsp. avenae (Aaa) is related to serious global losses in yield. However, the underlying molecular mechanisms associated with responses of sugarcane plants to infection by this pathogen remain largely unknown. Here, we used Illumina RNA-sequencing (RNA-seq) to perform large-scale transcriptome sequencing of two sugarcane cultivars to contrast gene expression patterns of plants between Aaa and mock inoculations, and identify key genes and pathways involved in sugarcane defense responses to Aaa infection. At 0–72 hours post-inoculation (hpi) of the red stripe disease-resistant cultivar ROC22, a total of 18,689 genes were differentially expressed between Aaa-inoculated and mock-inoculated samples. Of these, 8498 and 10,196 genes were up- and downregulated, respectively. In MT11-610, which is susceptible to red stripe disease, 15,782 genes were differentially expressed between Aaa-inoculated and mock-inoculated samples and 8807 and 6984 genes were up- and downregulated, respectively. The genes that were differentially expressed following Aaa inoculation were mainly involved in photosynthesis and carbon metabolism, phenylpropanoid biosynthesis, plant hormone signal transduction, and plant–pathogen interaction pathways. Further, qRT-PCR and RNA-seq used for additional validation of 12 differentially expressed genes (DEGs) showed that eight genes in particular were highly expressed in ROC22. These eight genes participated in the biosynthesis of lignin and coumarin, as well as signal transduction by salicylic acid, jasmonic acid, ethylene, and mitogen-activated protein kinase (MAPK), suggesting that they play essential roles in sugarcane resistance to Aaa. Collectively, our results characterized the sugarcane transcriptome during early infection with Aaa, thereby providing insights into the molecular mechanisms responsible for bacterial tolerance. [ABSTRACT FROM AUTHOR]

Sugarcane (Saccharum spp. hybrids) is a major source of sugar and renewable bioenergy crop worldwide and suffers serious yield losses due to many pathogen infections. Leaf scald caused by Xanthomonas albilineans is a major bacterial disease of sugarcane in most sugarcane-planting countries. The molecular mechanisms of resistance to leaf scald in this plant are, however, still unclear. We performed a comparative transcriptome analysis between resistant (LCP 85-384) and susceptible (ROC20) sugarcane cultivars infected by X. albilineans using the RNA-seq platform. 24 cDNA libraries were generated with RNA isolated at four time points (0, 24, 48, and 72 h post inoculation) from the two cultivars with three biological replicates. A total of 105,783 differentially expressed genes (DEGs) were identified in both cultivars and the most upregulated and downregulated DEGs were annotated for the processes of the metabolic and single-organism categories, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the 7612 DEGs showed that plant–pathogen interaction, spliceosome, glutathione metabolism, protein processing in endoplasmic reticulum, and plant hormone signal transduction contributed to sugarcane's response to X. albilineans infection. Subsequently, relative expression levels of ten DEGs determined by quantitative reverse transcription-PCR (qRT-PCR), in addition to RNA-Seq data, indicated that different plant hormone (auxin and ethylene) signal transduction pathways play essential roles in sugarcane infected by X. albilineans. In conclusion, our results provide, for the first time, valuable information regarding the transcriptome changes in sugarcane in response to infection by X. albilineans, which contribute to the understanding of the molecular mechanisms underlying the interactions between sugarcane and this pathogen and provide important clues for further characterization of leaf scald resistance in sugarcane. [ABSTRACT FROM AUTHOR]

Objective: The selection of reference genes in sugarcane under Sugarcane mosaic virus (SCMV) infection has not been reported and is indispensable to get reliable reverse transcription quantitative PCR (RT-qPCR) results for validation of transcriptome analysis. In this regard, seven potential reference genes were tested by RT-qPCR and ranked according to their stability using BestKeeper, NormFinder and GeNorm algorithms, and RefFinder WEB-based software in an experiment performed with samples from two sugarcane cultivars contrasting for SCMV resistance, when mechanically inoculated with a severe SCMV strain and using mock inoculated plant controls. Results: The genes Uridylate kinase (UK) and Ubiquitin-conjugating enzyme 18 (UBC18) were the most stable according to GeNorm algorithm and the Pearson correlation coefficients with the BestKeeper index. On the other hand, ribosomal protein L35-4 (RPL1), Actin (ACT) and Ubiquitin1 (UBQ1) were the least stable genes for all algorithms tested. [ABSTRACT FROM AUTHOR]