Novel Insights into Anthocyanin Metabolism and Molecular Characterization of Associated Genes in Sugarcane Rinds Using the Metabolome and Transcriptome.

Saccharum officinarum (sugarcane) is the fifth major cultivated crop around the world. Sugarcane rind is a promising source for anthocyanin pigments; however, limited information is available on the anthocyanin and its biosynthesis in sugarcane rinds. In this study, we have quantified 49 compounds including 6 flavonoids and 43 anthocyanins in the rind of 6 sugarcane cultivars by using LCMS/MS approach. Thirty of them were quantified for the first time in sugarcane. The 43 anthocyanins included 10 cyanidin (Cya), 11 pelargonidin (Pel), 9 peonidin (Peo), 5 malvidin (Mal), 4 delphinidin (Del), and 4 petunidin (Pet) metabolites. High contents of Cya derivatives were observed in the rind of YT71/210 (dark purple rind), such as cya-3-O-(6-O-malonyl)-glu 1283.3 µg/g and cya-3-O-glu 482.67 µg/g followed by ROC22 (red rind) 821.3 µg/g and 409 µg/g, respectively, whereas the YT93/159 (green rind) showed a minimum level of these compounds. Among six cultivars, ROC22 rind has high levels of Peo derivatives such as peo-3-O-glu (197 µg/g), peo-3-O-(6-O-malonyl)-glu (69 µg/g) and peo-3-O-(6-O-p-coumaryl)-glu (55.17 µg/g). The gene expression analysis revealed that some genes, including a MYB(t) gene, were highly associated with the color phenotype. Thus, we cloned and overexpressed the gene in Arabidopsis and found the pinkish brown color in the hypocotyl of all transgenic lines compared with the wild type. Hence, we have quantified a wide range of anthocyanins in major sugarcane cultivars, reported many new anthocyanins for the first time, and concluded that Cya and Peo derivatives are the major contributing factor of dissimilar colors in sugarcane. The finding and the verification of a novel MYB gene involved in anthocyanin biosynthesis have demonstrated that our study was very valuable for gene discovery and genetic improvement of sugarcane cultivars to harvest high anthocyanin contents.

Revisiting the physical mutagenesis for sugarcane improvement: a stomatal prospective.

This study was conducted to investigate the influence of gamma rays on stomatal parameters and the interaction of these traits with agronomy of the sugarcane crop. Three genotypes of sugarcane (NIA-0819, NIA-98, and BL4) were exposed to four doses of gamma radiation (10, 20, 30, and 40 Gy) and then subjected to field trials. Stomatal length, width, and density were observed using scanning electron microscopy. Moreover, agronomic and sugar-related characteristics of the crop were determined at maturity. The stomatal parameters augmented at two lower doses of gamma radiation (10 and 20 Gy) and declined under higher doses (30 and 40 Gy). The maximum stomatal length was observed in NIA-0819 at 10 Gy (63.71 µm), whereas NIA-98 and BL4 demonstrated highest stomatal length under 20 Gy (54.11 and 57.40 µm, respectively), indicating a role of genetic factors in varietal response. Similar trend was noticed for stomatal width and density as well. The lowermost treatment (10 Gy) of NIA-0819 produced maximum stomatal density (115.31 stomata mm-2 on the abaxial surface). Adaxial stomatal density was significantly lower than the abaxial one. Sugar quality attributes revealed a different tendency. Sucrose contents of BL4 increased gradually from 12.33% at control to 14.54% at 40 Gy. Yield and yield-contributing traits of genotypes indicated a strong positive correlation with the stomatal parameters. The present study suggested that gamma radiations cause variations in stomatal characteristics of sugarcane. These changes further influence the photosynthetic activity and instigate a direct impact on the agronomic performance of the crop.

Evaluation of the cold tolerance of Saccharum spontaneum L. clones with different ploidy levels on the basis of morphological and physiological indices.

Saccharum spontaneum L. is one of the most important germplasm resources for modern sugarcane breeding. Exploring the cold tolerance of S. spontaneum clones with different ploidy levels and screening for cold-tolerant material can be helpful in parent selection for breeding cold-tolerant sugarcane. Morphological indices, leaf ultrastructure and physiological indices were used to evaluate the cold tolerance of 36 S. spontaneum clones with different ploidy levels (2n = 40, 48, 54, 60, 64, 78, 80, 88, 92 and 96). The morphological indices of S. spontaneum clones with different ploidy levels were positively correlated with ploidy. Under low-temperature stress, the chloroplast and mitochondrial structures of the clones with high ploidy were more severely damaged than were those of clones with low ploidy. A comprehensive evaluation of the physiological indices showed that the 36 S. spontaneum clones could be divided into four categories: strongly cold tolerant, cold tolerant, moderately cold tolerant and cold sensitive. Correlation analysis of the morphological indices and cold tolerance revealed a significant negative correlation between cold tolerance and ploidy. On the basis of the morphological and physiological indices, optimal stepwise regression equations that can be used for the selection of cold-tolerant S. spontaneum resources were established. The S. spontaneum clones with low ploidy are more cold tolerant than those with high ploidy. Clones 12-37, 13-10 and 12-23 are strongly cold-tolerant germplasm resources, which suggests these germplasm sources have high potential for use in breeding cold-tolerant sugarcane.

Saccharum angustifolium (Nees) Trin. (Poales: Poaceae) as hibernacle for stink bugs during the soybean and corn off-season in Southern Brazil / Saccharum angustifolium (Nees) Trin. (Poales: Poaceae) como hibernáculo para percevejos durante a entressafra de soja e milho no sul do Brasil

Host plants are key factors in the survival of true bugs during unfavorable periods. The objective of this study was to evaluate the composition, diversity and abundance of pentatomid bugs in Saccharum angustifolium (Nees) Trin. (Poales: Poaceae). Plants were evaluated during the soybean and corn off--season for five years. A total of 250 plants were sampled, the true bug population was counted and used for statistical and faunistic analysis. We observed the occurrence of the species: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.), and Edessa ruformaginata (De Geer). Among the species, the highest population density was verified for E. meditabunda, E. heros, and D. furcatus. We also observed a direct effect of the clump diameter on the population density of E. heros, D. furcatus, and E. meditabunda. Finally, we conclude that S. angustifolium plants serve as adequate hibernacles for the survival of true bugs of economic importance during the soybean and corn off-season.(AU)

Plantas hospedeiras são fatores fundamentais na sobrevivência de percevejos durante períodos desfavoráveis. O objetivo deste trabalho foi avaliar a composição, diversidade e abundância de espécies de percevejos pentatomídeos ocorrentes em plantas de Saccharum angustifolium (Nees) Trin (Poales: Poaceae). As plantas foram avaliadas durante a entressafra de soja e milho por cinco anos. Foram amostradas 250 plantas, sendo a população de percevejos contabilizada e utilizada para a análise estatística e faunística. Observamos a ocorrência das espécies: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.) e Edessa ruformaginata (De Geer). Entre as espécies, foi verificada uma maior densidade populacional para E. meditabunda, E. heros e D. furcatus. Observamos, também, o efeito direto do diâmetro de touceira sobre a densidade populacional de E. heros, D. furcatus e E. meditabunda. Por fim, concluímos que plantas de S. angustifolium servem como hibernáculos adequados para a sobrevivência de percevejos de importância econômica durante a entressafra de soja e milho.(AU)

Drought tolerance of sugarcane is improved by previous exposure to water deficit.

Under field conditions, plants are exposed to cycles of dehydration and rehydration during their lifespan. In this study, we hypothesized that sugarcane plants previously exposed to cycles of water deficits will perform better than plants that have never faced water deficits when both are subjected to low water availability. Sugarcane plants were grown in a nutrient solution and exposed to one (1WD), two (2WD) or three (3WD) water deficit cycles. As the reference, plants were grown in a nutrient solution without adding polyethylene glycol. Under water deficits, leaf gas exchange was significantly reduced in 1WD and 2WD plants. However, 3WD plants showed similar CO2 assimilation and lower stomatal conductance compared to the reference plants, with increases in intrinsic water-use efficiency. Abscisic acid concentrations were lower in 3WD plants than in 1WD plants. Our data revealed root H2O2 concentration as an important chemical signal, with the highest root H2O2 concentrations found in 3WD plants. These plants presented higher root dry matter and root:shoot ratios compared to the reference plants, as well as higher biomass production when water was available. Our data suggest that sugarcane plants were able to store information from previous stressful events, with plant performance improving under water deficits. In addition, our findings provide a new perspective for increasing drought tolerance in sugarcane plants under nursery conditions.

Roles of auxin and ethylene in aerenchyma formation in sugarcane roots.

Although the cross-talk between auxin and ethylene has been described during plant development, the role played by auxin upon gene expression during aerenchyma formation is poorly understood. Root aerenchyma formation results from the opening of gas spaces in the cortex. It is part of a developmental program (constitutive) or due to ethylene treatment or abiotic stress (induced) such as flooding and nutrient starvation. This process relies on programmed cell death and cell wall modifications. Here we followed development of aerenchyma formation in sugarcane along 5 cm from the root apex. As a constitutive process, the aerenchyma formation was observed in the cortex from the 3rd cm onwards. This occurred despite 1-methylcyclepropene (1-MCP) treatment, an inhibitor of ethylene perception. However, this process occurred while ethylene (and auxin) levels decreased. Within the aerenchyma formation zone, the concentration of ethylene is lower in comparison to the concentration in maize. Besides, the ratio between both hormones (ethylene and auxin) was around 1:1. These pieces of evidence suggest that ethylene sensitivity and ethylene-auxin balance may play a role in the formation of aerenchyma. Furthermore, the transcriptional analysis showed that genes related to cell expansion are up-regulated due to 1-MCP treatment. Our results help explaining the regulation of the formation constitutive aerenchyma in sugarcane.

Anatomical, morphological, and physiological responses of two sugarcane genotypes of contrasting susceptibility to Mahanarva fimbriolata (Hemiptera: Cercopidae).

The purpose of this study was to investigate and compare root morpho-anatomical traits and physiological responses of susceptible (SP81-3250) and resistant (H. Kawandang) sugarcane genotypes exposed to the attack by nymphs of spittlebug Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae). Two experiments were conducted to compare the damage caused by spittlebug nymphs on fresh and dry biomass weight; lignin content in stalks; root anatomy; chlorophyll content; photosynthetic rate (A); carboxylation efficiency (A/Ci); stomatal conductance (gS) and transpiration rate (E) of these genotypes. SP81-3250 consistently obtained significantly higher damage scores than H. Kawandang in both experiments, confirming the previously observed level of resistance in each genotype. Attack by spittlebug nymphs had a much higher effect on both fresh and dry biomass weight, chlorophyll content, A, A/Ci, gs and E of SP81-3250, than that on H. Kawandang. Anatomical studies indicated the presence of aerenchyma tissue in the root cortex of SP81-3250, a feature which may facilitate penetration of the nymph's stylet into the vascular cylinder. In contrast, roots of H. Kawandang are characterized by having more dense and compact parenchyma cells. In addition, infested plants of this genotype contained an unidentified mucilaginous compound in the vascular cylinder of the roots. We conclude that resistance of H. Kawandang to spittlebug is related to the ability of this genotype to maintain normal chlorophyll content, as well as stomatal conductance and photosynthesis, thus, allowing for biomass accumulation under spittlebug attack, in contrast to SP81-3250. In addition, the presence of more compact and denser parenchymal cells, as well as that of an induced mucilaginous compound in the root's vascular cylinder, are likely to hinder host-feeding activity in nymphs, causing higher nymph mortality and therefore, reduced damage in plants of this genotype.

Analysis of a Modern Hybrid and an Ancient Sugarcane Implicates a Complex Interplay of Factors in Affecting Recalcitrance to Cellulosic Ethanol Production.

Abundant evidence exists to support a role for lignin as an important element in biomass recalcitrance. However, several independent studies have also shown that factors apart from lignin are also relevant and overall, the relative importance of different recalcitrance traits remains in dispute. In this study we used two genetically distant sugarcane genotypes, and performed a correlational study with the variation in anatomical parameters, cell wall composition, and recalcitrance factors between these genotypes. In addition we also tracked alterations in these characteristics in internodes at different stages of development. Significant differences in the development of the culm between the genotypes were associated with clear differential distributions of lignin content and composition that were not correlated with saccharification and fermentation yield. Given the strong influence of the environment on lignin content and composition, we hypothesized that sampling within a single plant could allow us to more easily interpret recalcitrance and changes in lignin biosynthesis than analysing variations between different genotypes with extensive changes in plant morphology and culm anatomy. The syringyl/guaiacyl (S/G) ratio was higher in the oldest internode of the modern genotype, but S/G ratio was not correlated with enzymatic hydrolysis yield nor fermentation efficiency. Curiously we observed a strong positive correlation between ferulate ester level and cellulose conversion efficiency. Together, these data support the hypothesis that biomass enzymatic hydrolysis recalcitrance is governed by a quantitative heritage rather than a single trait.

Transcriptome profiling of sugarcane roots in response to low potassium stress.

Sugarcane is the most important crop for supplying sugar. Due to its high biomass, sugarcane needs to absorb a large amount of potassium (K) throughout its lifecycle. In South China, a deficiency of K available in soil restricts the production of sugarcane. Increasing the tolerance of sugarcane to low-K will be an effective approach for improving survival of the crop in this area. However, there is little information regarding the mechanism of tolerance to low-K stress in sugarcane. In this study, a customized microarray was used to analyze the changes in the level of transcripts of sugarcane genes 8 h, 24 h and 72 h after exposure to low-K conditions. We identified a total of 4153 genes that were differentially expressed in at least one of the three time points. The number of genes responding to low-K stress at 72 h was almost 2-fold more than the numbers at 8 h and 24 h. Gene ontology (GO) analysis revealed that many genes involved in metabolic, developmental and biological regulatory processes displayed changes in the level of transcripts in response to low-K stress. Additionally, we detected differential expression of transcription factors, transporters, kinases, oxidative stress-related genes and genes in Ca+ and ethylene signaling pathways; these proteins might play crucial roles in improving the tolerance of sugarcane to low-K stress. The results of this study will help to better understand the molecular mechanisms of sugarcane tolerance to low-K.

Phylogenetic analysis of Saccharum s.l. (Poaceae; Andropogoneae), with emphasis on the circumscription of the South American species.

PREMISE OF THE STUDY: Polyploidy and reticulate evolution are often a complication for discovering phylogenetic relationships between genera and species. Despite the huge economic importance of sugarcane (Saccharum officinarum-Poaceae, Andropogoneae), the limits of the genus Saccharum and its species are complex and largely unresolved, involving both polyploidy and reticulate evolution. This study aimed to assess the phylogenetic relationships of Saccharum s.l., including Erianthus and Tripidium, as well as investigate the taxonomic circumscription of the South American species of the genus. METHODS: Molecular cloning and sequencing of five regions of four low-copy nuclear loci were performed, including Aberrant panicle organization1 (apo1), Dwarf8 (d8), two exons of Erect panicle2 (ep2-ex7 and ep2-ex8), and Retarded palea1 (rep1). Concatenated trees were reconstructed using Maximum Parsimony, Maximum Likelihood, and Bayesian Inference analyses. KEY RESULTS: The allopolyploid origin of Saccharum was demonstrated using evidence from nuclear genes. The samples of Saccharum s.l. grouped in two distinct clades, with S. arundinaceum and S. ravennae (= Tripidium, or Erianthus sect. Ripidium) apart from all other species analyzed of the genus. Saccharum angustifolium, S. asperum, and S. villosum correspond to distinct clades (different species). The plants with intermediate morphology between S. angustifolium and S. villosum presented a pattern of paralogues consistent with a hybrid origin. CONCLUSIONS: Saccharum s.l. is polyphyletic and Tripidium should be recognized as a distinct genus. However, no strong evidence was found to support the segregation of Erianthus. The taxonomic circumscription of the South American species of the genus was resolved and the occurrence of natural hybrids was documented. Better understanding of the phylogenetic relationships of Saccharum and relatives may be useful for sugarcane breeders to identify potential taxa for interspecific and intergeneric crosses in the genetic improvement of sugarcane.

Photosynthetic and canopy characteristics of different varieties at the early elongation stage and their relationships with the cane yield in sugarcane.

During sugarcane growth, the Early Elongation stage is critical to cane yield formation. In this study, parameters of 17 sugarcane varieties were determined at the Early Elongation stage using CI-301 photosynthesis measuring system and CI-100 digital plant canopy imager. The data analysis showed highly significant differences in leaf area index (LAI), mean foliage inclination angle (MFIA), transmission coefficient for diffused light penetration (TD), transmission coefficient for solar beam radiation penetration (TR), leaf distribution (LD), net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (GS) among sugarcane varieties. Based on the photosynthetic or canopy parameters, the 17 sugarcane varieties were classified into four categories. Through the factor analysis, nine parameters were represented by three principal factors, of which the cumulative rate of variance contributions reached 85.77%. A regression for sugarcane yield, with relative error of yield fitting less than 0.05, was successfully established: sugarcane yield = -27.19 - 1.69 × PN + 0.17 × E + 90.43 × LAI - 408.81 × LD + 0.0015 × NSH + 101.38 × D (R(2) = 0.928**). This study helps provide a theoretical basis and technical guidance for the screening of new sugarcane varieties with high net photosynthetic rate and ideal canopy structure.

Accumulation pattern of dehydrins during sugarcane (var. SP80.3280) somatic embryogenesis.

UNLABELLED: The objective of the present study was to determine dehydrin protein levels in sugarcane var. SP80-3280 during somatic embryogenesis. Dehydrins from embryogenic and non-embryogenic cell cultures were analyzed using western blot and in situ immunolocalization microscopy. Both techniques employ antibodies raised against a highly conserved lysine-rich 15-amino acid sequence termed the K-domain, which is extensively used to recognize proteins immunologically related to the dehydrin family. In embryogenic cultures, western blot analysis of the heat-stable protein fraction revealed eleven major bands ranging from 52 to 17 kDa. They were already visible on the first days, gradually increasing until reaching peak values around day 14, when organogenesis begins, to later decrease in concurrence with the appearance of green plantlets (around day 28). These fluctuations indicate that this pattern of accumulation is under developmental control. Dehydrins were mainly immunolocalized in the nuclei. A phosphatase treatment of protein extracts caused a mobility shift of the 52, 49, and 43 kDa dehydrin bands suggesting a putative modulation mechanism based on protein phosphorylation. In sugarcane embryogenic cultures, presence of dehydrins is a novel finding. Dehydrins were absent in non-embryogenic cultures. The novel findings regarding accumulation, nuclear localization, and phosphorylation of dehydrins provide a starting point for further research on the role of these proteins in the induction and/or maintenance of embryogenesis. KEY MESSAGE: The novel findings regarding accumulation, nuclear localization, and phosphorylation of dehydrins provide a starting point for further research on the role of these proteins in the induction and/or maintenance of embryogenesis.

Genetic control of yield related stalk traits in sugarcane.

A major focus of sugarcane variety improvement programs is to increase sugar yield, which can be accomplished by either increasing the sugar content of the cane or by increasing cane yield, as the correlation between these traits is low. We used a cross between an Australian sugarcane variety Q165, and a Saccharum officinarum accession, IJ76-514, to dissect the inheritance of yield-related traits in the complex polyploid sugarcane. A population of 227 individuals was grown in a replicated field trial and evaluated over 3 years for stalk weight, stalk diameter, stalk number, stalk length and total biomass. Over 1,000 AFLP and SSR markers were scored across the population and used to identify quantitative trait loci (QTL). In total, 27 regions were found that were significant at the 5% threshold using permutation tests with at least one trait; individually, they explained from 4 to 10% of the phenotypic variation and up to 46% were consistent across years. With the inclusion of digeneic interactions, from 28 to 60% of the variation was explained for these traits. The 27 genomic regions were located on 22 linkage groups (LGs) in six of the eight homology groups (HGs) indicating that a number of alleles or quantitative trait alleles (QTA) at each QTL contribute to the trait; from one to three alleles had an effect on the traits for each QTL identified. Alleles of a candidate gene, TEOSINTE BRANCHED 1 (TB1), the major gene controlling branching in maize, were mapped in this population using either an SSR or SNP markers. Two alleles showed some association with stalk number, but unlike maize, TB1 is not a major gene controlling branching in sugarcane but only has a minor and variable effect.

Water stress augments silicon-mediated resistance of susceptible sugarcane cultivars to the stalk borer Eldana saccharina (Lepidoptera: Pyralidae).

Silicon (Si) can improve resistance of plants to insect attack and may also enhance tolerance of water stress. This study tested if Si-mediated host plant resistance to insect attack was augmented by water stress. Four sugarcane cultivars, two resistant (N21, N33) and two susceptible (N26, N11) to Eldana saccharina Walker were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si-) calcium silicate. To induce water stress, irrigation to half the trial was reduced after 8.5 months. The trial was artificially infested with E. saccharina eggs after water reduction and harvested 66 days later. Silicon treated, stressed and non-stressed plants of the same cultivar did not differ appreciably in Si content. Decreases in numbers of borers recovered and stalk damage were not associated with comparable increases in rind hardness in Si+ cane, particularly in water-stressed susceptible cultivars. Overall, Si+ plants displayed increased resistance to E. saccharina attack compared with Si- plants. Borer recoveries were significantly lower in stressed Si+ cane compared with either stressed Si- or non-stressed Si- and Si+ cane. Generally, fewer borers were recovered from resistant cultivars than susceptible cultivars. Stalk damage was significantly lower in Si+ cane than in Si- cane, for N21, N11 and N26. Stalk damage was significantly less in Si+ combined susceptible cultivars than in Si- combined susceptible cultivars under non-stressed and especially stressed conditions. In general, the reduction in borer numbers and stalk damage in Si+ plants was greater for water-stressed cane than non-stressed cane, particularly for susceptible sugarcane cultivars. The hypothesis that Si affords greater protection against E. saccharina borer attack in water-stressed sugarcane than in non-stressed cane and that this benefit is greatly enhanced in susceptible cultivars is supported. A possible active role for soluble Si in defence against E. saccharina is proposed.

Genetic analysis for brix weight per stool and its component traits in sugarcane (Saccharum officinarum).

Brix weight per stool (BW) of sugarcane is a complex trait, which is the final product of a combination of many components. Diallel cross experiments were conducted during a period of two years for BW and its five component traits, including stalk diameter (SD), stalk length (SL), stalk number (SN), stalk weight (SW), and brix scale (BS) of sugarcane. Phenotypic data of all the six traits were analyzed by mixed linear model and their phenotype variances were portioned into additive (A), dominance (D), additive x environment interaction (AE) and dominance x environment interaction (DE) effects, and the correlations of A, D, AE and DE effects between BW and its components were estimated. Conditional analysis was employed to investigate the contribution of the components traits to the variances of A, D, AE and DE effects of BW. It was observed that the heritabilities of BW were significantly attributed to A, D and DE by 23.9%, 30.9% and 28.5%, respectively. The variance of A effect for BW was significantly affected by SL, SN and BS by 25.3%, 93.7% and 17.4%, respectively. The variances of D and DE effects for BW were also significantly influenced by all the five components by 5.1%(85.5%. These determinants might be helpful in sugarcane breeding and provide valuable information for multiple-trait improvement of BW.

Sugarcane (Saccharum spp.).

We describe the procedures for recovering transgenic sugarcane from co-cultivation of both calli and in vitro plants with Agrobacterium tumefaciens. The correct tissue culture strategies and the use of super-binary vector or super-virulent strain are crucial for the successful sugarcane transformation. Both plant regeneration via calli culture and micropropagation strategies can be optimized to a wide spectrum of sugarcane genotypes, thus the procedures presented here could be applied to genetic engineering of Saccharum spp. after minor modifications. For the case of sugarcane transformation using in vitro plants, four selective micropropagation steps must be sufficient to eliminate chimera plants.

Comparative analysis of QTLs affecting plant height and flowering among closely-related diploid and polyploid genomes.

Quantitative trait loci (QTLs) affecting plant height and flowering were studied in the two Saccharum species from which modern sugarcane cultivars are derived. Two segregating populations derived from interspecific crosses between Saccharum officinarum and Saccharum spontaneum were genotyped with 735 DNA markers. Among the 65 significant associations found between these two traits and DNA markers, 35 of the loci were linked to sugarcane genetic maps and 30 were unlinked DNA markers. Twenty-one of the 35 mapped QTLs were clustered in eight genomic regions of six sugarcane homologous groups. Some of these could be divergent alleles at homologous loci, making the actual number of genes implicated in these traits much less than 35. Four QTL clusters controlling plant height in sugarcane corresponded closely to four of the six plant-height QTLs previously mapped in sorghum. One QTL controlling flowering in sugarcane corresponded to one of three flowering QTLs mapped in sorghum. The correspondence in locations of QTLs affecting plant height and flowering in sugarcane and sorghum reinforce the notion that the simple sorghum genome is a valuable "template" for molecular dissection of the much more complex sugarcane genome.