Leaf Scald Research Articles

Silicon alleviates mesophyll limitations of photosynthesis on rice leaves infected by Monographella albescens

Leaf scald, caused by Monographella albescens, is a key disease affecting rice production worldwide. Alternative methods for leaf scald management are demanded by the growers and silicon (Si) application emerges as a promising way to decrease severity not only of leaf scald but also of other relevant rice diseases. Some evidence suggests that Si may preserve the photosynthetic performance of plants upon pathogen infection but the mechanistic basis for this remain unresolved. In the present study, mesophyll conductance (gm) was calculated to suitably parameterize the responses of net carbon assimilation rate (A) to chloroplastidic CO2 concentration (Cc) and to resolve the relative contributions of stomatal, mesophyll, and biochemical drawbacks to photosynthesis in rice plants challenged with M. albescens and how all of these facts may be influenced by Si application. Rice plants (cultivar “Primavera”) were hydroponically grown with 0 or 2 mM Si (− Si and + Si plants) and inoculated with M. albescens. Leaf scald-induced decreases in A were associated with roughly proportional decreases in CO2 diffusion (lower stomatal conductance and gm) and impaired photochemistry (e.g. reduced maximum electron transport rate) and biochemistry (e.g. RuBisCO activity) regardless of Si supply. The magnitude of these decreases were, overall, greater in − Si plants than in their + Si counterparts, and therefore a mitigating effect of Si on the preservation of the photosynthetic activity on diseased plants is evident. On infected leaves, gm was not scaled with maximum carboxylation rate (Vcmax) − Cc and, as a consequence, Cc increased accordingly, but only in + Si plants. In conclusion, the supply of Si to rice plants played a central role in decreasing leaf scald symptoms and, as such, preserving to a certain extent their photosynthetic performance. This preservation was not linked to differential impairments on the stomatal function or biochemical steps of photosynthesis but rather with increased CO2 diffusion throughout the mesophyll. This ultimately led to a lower photorespiration-to-gross photosynthesis ratio and less mesophyll limitations of photosynthesis in + Si plants than in their − Si counterparts during the infection process of M. albescens on rice leaves.

Detection of QTL and QTL × environment interaction for scald resistance in a two-row × six-row cross of barley

Leaf scald caused by Rhynchosporium secalis, is a serious disease of barley (Hordeum vulgare L.) in Tunisia. A doubled-haploid barley population, from a cross between the two-rowed ‘Roho’ and the six-rowed ‘L90’ cultivars, was evaluated for its reaction to scald under natural infection in replicated field trials for two years. Phenotypic variation among doubled-haploid lines was significant for disease reaction in both environments (cropping seasons) and genotype × environment interaction was also significant. Heritability estimates were high in both seasons and significant correlation was noted between scald reactions recorded in the two seasons. Segregation of 34 single sequence repeat markers was used for quantitative trait loci mapping. Single-marker analysis was applied for individual and for combined environments to determine the effect of each molecular marker on scald resistance. In total, six QTLs with additive effects were mapped on chromosomes 2H, 3H, 4H, 6H and 7H which explained from 4.4 to 11.7% of the phenotypic variance. Among these, only QTLs linked to WMS6 (4H) and to HVM31 (6H) showed significant QTL × environment interactions. QTLs associated to HVM36 (2H) and to Bmag0571 (7H) were the most significant for scald resistance and the most insensitive to the environment. Another stable QTL was identified, for the first time, in the vicinity of the Vrs1 locus on the 2H chromosome. For this QTL, the two-rowed parental allele reduced disease severity. These chromosomal regions that affect scald resistance independently of the environment would be of great interest in marker-assisted selection.

Complete Genome Sequence Reveals Evolutionary and Comparative Genomic Features of Xanthomonas albilineans Causing Sugarcane Leaf Scald.

Leaf scald (caused by Xanthomonas albilineans) is an important bacterial disease affecting sugarcane in most sugarcane growing countries, including China. High genetic diversity exists among strains of X. albilineans from diverse geographic regions. To highlight the genomic features associated with X. albilineans from China, we sequenced the complete genome of a representative strain (Xa-FJ1) of this pathogen using the PacBio and Illumina platforms. The complete genome of strain Xa-FJ1 consists of a circular chromosome of 3,724,581 bp and a plasmid of 31,536 bp. Average nucleotide identity analysis revealed that Xa-FJ1 was closest to five strains from the French West Indies and the USA, particularly to the strain GPE PC73 from Guadeloupe. Comparative genomic analysis between Xa-FJ1 and GPE PC73 revealed prophage integration, homologous recombination, transposable elements, and a clustered regulatory interspaced short palindromic repeats (CRISPR) system that were linked with 16 insertions/deletions (InDels). Ten and 82 specific genes were found in Xa-FJ1 and GPE PC73, respectively, and some of these genes were subjected to phage-related proteins, zona occludens toxin, and DNA methyltransferases. Our findings highlight intra-species genetic variability of the leaf scald pathogen and provide additional genomic resources to investigate its fitness and virulence.

Identification of Differentially Expressed Proteins in Sugarcane in Response to Infection by Xanthomonas albilineans Using iTRAQ Quantitative Proteomics.

Sugarcane can suffer severe yield losses when affected by leaf scald, a disease caused by Xanthomonas albilineans. This bacterial pathogen colonizes the vascular system of sugarcane, which can result in reduced plant growth and plant death. In order to better understand the molecular mechanisms involved in the resistance of sugarcane to leaf scald, a comparative proteomic study was performed with two sugarcane cultivars inoculated with X. albilineans: one resistant (LCP 85-384) and one susceptible (ROC20) to leaf scald. The iTRAQ (isobaric tags for relative and absolute quantification) approach at 0 and 48 h post-inoculation (hpi) was used to identify and annotate differentially expressed proteins (DEPs). A total of 4295 proteins were associated with 1099 gene ontology (GO) terms by GO analysis. Among those, 285 were DEPs during X. albilineans infection in cultivars LCP 85-384 and ROC20. One hundred seventy-two DEPs were identified in resistant cultivar LCP 85-384, and 113 of these proteins were upregulated and 59 were downregulated. One hundred ninety-two DEPs were found in susceptible cultivar ROC20 and half of these (92) were upregulated, whereas the other half corresponded to downregulated proteins. The significantly upregulated DEPs in LCP 85-384 were involved in metabolic pathways, the biosynthesis of secondary metabolites, and the phenylpropanoid biosynthesis pathway. Additionally, the expression of seven candidate genes related to photosynthesis and glycolytic pathways, plant innate immune system, glycosylation process, plant cytochrome P450, and non-specific lipid transfer protein was verified based on transcription levels in sugarcane during infection by X. albilineans. Our findings shed new light on the differential expression of proteins in sugarcane cultivars in response to infection by X. albilineans. The identification of these genes provides important information for sugarcane variety improvement programs using molecular breeding strategies.

Comparative Transcriptome Profiling of Resistant and Susceptible Sugarcane Cultivars in Response to Infection by Xanthomonas albilineans.

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.

Comparison of Five DNA Extraction Methods for Detection of Leaf Scald in Sugarcane Through PCR

The sugarcane cultivation in Brazil is expanding. The production area has increased considerably in 2011, most significantly in the states of Minas Gerais...

Sugarcane Leaf Scald Disease in Côte d'Ivoire: Pathogenicity and Biocontrol of Xanthomonas albilineans Isolates

Aims: The present investigations describes bactericidal potential of essential oil for management of Xanthomonas albilineans (Ashby. 1929) Dowson 1943, pathogen responsible for sugarcane Leaf scald disease in Côte d'Ivoire.
 Study Design: the study was conducted at the Ferké 1 sugar mill and the Laboratory of Plant Physiology of Felix Houphouët BOIGNY University.
 Methodology: Diseased leaves specimens showing signs of X. albilineans presence were collected from sugarcane industrial plantations in Côte d'Ivoire. Pathogenicity was confirmed by observing Koch’s postulates under semi-controlled conditions. Asymptomatic leaves, obtained after 60 days of culture, were inoculated at three points by infiltration with bacterial suspension calibrated at 108 bacteria/ml. Apparition of small tan-brown necrotic lesions on the leaf blade, parallel to the veins and prolonged to the ends by a discolored vascular bundle confirmed that disease is caused by Xanthomonas albilineans. Three essential oils of aromatic plants whose antibacterial properties are recognized were used at 100; 300; 500; 1000 and 2000 ppm in comparison with Callicuivre (56% copper oxychloride) used as reference product.
 Results: The aqueous solutions based on these essential oils induced an inhibition zone of bacterial growth proportional to the dose applied and the incubation period. Thus, on day 5 of incubation, the essential oil solution of Ocimum gratissimum L. at 100 ppm induced an average inhibition zone diameter not significantly different from the one induced by the Cymbopogon citratus (DC.) Stapf solution at 300 ppm and the one of copper oxychloride at 1000 ppm. At 1000 ppm, Zingiber officinale Roscoe, Cymbopogon citratus (DC.) Stapf and Ocimum gratissimum L essential oils induced equivalent inhibition rates (6 mm) that were higher than that of the control (3.5 mm).
 Conclusion: sugarcane varieties cultivated at the Ferké 1 sugar mill complex, despite the selection for resistance are threatened by Leaf Scald Disease, which is significantly expressed on variety R585. Cymbopogon citratus (DC.) Stapf and Ocimum gratissimum L oils have the strongest antibacterial activity and may be useful to control Leaf Scald Disease.

Complete genome dynamics of a dominant-lineage strain of Xanthomonas oryzae pv. oryzae harbouring a novel plasmid encoding a type IV secretion system.

Xanthomonas oryzae pv. oryzae (Xoo) is a serious pathogen causing bacterial blight disease in rice. Population genomic studies have revealed that rampant inter-strain rather than inter-lineage differences are contributing to the evolutionary success of this pathogen. Here, we report the complete genome sequence of BXO1, a strain of Xoo belonging to a dominant lineage from India. A complete genome-based investigation revealed the presence of two plasmids, pBXO1-1 (66.7 kb) and pBXO1-2 (25.6 kb). The pBXO1-1 plasmid encodes 71 genes, 38 of which encode hypothetical proteins of unknown function. However, these hypothetical genes possess atypical GC content, pointing towards their acquisition and movement through horizontal gene transfer. Interestingly, pBXO1-2 encodes a type IV secretion system (T4SS), which is known to play an important role in the conjugative transfer of genetic material, and also provides fitness to pathogenic bacteria for their enhanced survival. Neither plasmid has been reported previously in any other complete Xoo genome published to date. Our analysis also revealed that the pBXO1-2 plasmid is present in Xanthomonas albilineans str. GPE PC73, which is known to cause leaf scald, a lethal disease in sugarcane. Our complete genome sequence analysis of BXO1 has provided us with detailed insights into the two novel strain-specific plasmids, in addition to decoding their functional capabilities, which were not assessable when using the draft genome sequence of the strain. Overall, our study has revealed the mobility of a novel T4SS in two pathogenic species of Xanthomonas that infect the vascular tissues of two economically important monocot plants, i.e. rice and sugarcane.

Registration of ‘CP 10‐1619’ Sugarcane for Use on Sand Soils

‘CP 10‐1619’ (Reg. no. CV‐191, PI 687220) sugarcane (a complex hybrid of Saccharum spp.) was developed and released (5 June 2017) through cooperative research conducted by the USDA‐ARS Sugarcane Field Station at Canal Point, the University of Florida, and the Florida Sugarcane League, Inc., for use on mineral (sand) soils. The cultivar was derived from polycross no. X08‐1197A (CP 97‐1777 × Poly 08‐19) and has high cane and sucrose yields, particularly in the plant cane, resulting in a high economic index on sand soils. Results of replicated trials on sand soils (2015–2017; three locations) were averaged over nine harvests from the three crops (i.e., plant cane, first ratoon, and second ratoon). Yield comparisons with check cultivars (‘CL 88‐4730’ and ‘CP 96‐1252’) indicated CP 10‐1619 had significantly higher means than CL 88‐4730 (P ≤ 0.10) for cane yield (131.6 Mg ha−1), sugar yield (16.5 Mg ha−1), and economic index (3037 $ ha−1). CP 10‐1619 had significantly (P ≤ 0.10) higher means than both check cultivars for stalk weight (0.9 kg stalk−1) and stalk count (134,350 stalks ha−1). CP 10‐1619 has demonstrated moderate resistance to both brown and orange rusts, as well as smut. CP 10‐1619 is resistant to mosaic and leaf scald on sand soils and is moderately susceptible to ratoon stunting disease. CP 10‐1619 is moderately resistant to freezing temperatures.

Selection of conilon coffee clones tolerant to pests and diseases in Minas Gerais

Abstract: In the northern Minas region, the dry-warm climate predisposes coffee plants to the occurrence of leaf miners, mites, cercosporiosis, and leaf scald. Aiming for the development of a cultivar adapted to these conditions, Coffea canephora Pierre ex A. Froehner clones were selected through genetic parameters under an irrigated system, without agrochemicals. Eighteen agronomic traits were evaluated. The survival rate, number of nodes per plagiotropic branch, leaf miner infestation and cercosporiosis incidence were chosen as characteristics for selection of Vitoria Incaper 8142 , once they have shown superiority of the genetic parameters. The survival rate variable was used to rank the EMCAPA 8141 Robustao Capixaba clones. Clones V2, V4, V6, V13, RC7, and RC9 were selected as more tolerant to pests and diseases and can provide genetic improvements in conilon breeding program for region. The genetic dissimilarity identified between clones allowed suitable clone combinations to be proposed for use in future crosses.

Registration of ‘CP 09‐4153’, ‘CPCL 09‐4160’, and ‘CP 09‐4758’ Sugarcane for Sand Soils in Florida

‘CP 09‐4153’ (Reg. no. CV‐189, PI 688442), ‘CPCL 09‐4160’ (Reg. no. CV‐188, PI 688443), and ‘CP 09‐4758’ (Reg. no. CV‐190, PI 688444) are new sugarcane (complex hybrids of Saccharum spp.) cultivars developed through cooperative research conducted by the USDA‐ARS, the University of Florida, and the Florida Sugar Cane League and released to be cultivated on mineral (sand) soils in Florida. Female and male parents, respectively are CPCL 97‐0393 and CPCL 02‐8021 for CP 09‐4153; ‘CP 80‐1743’ and Poly 01‐8 (a pollen mix) for CPCL 09‐4160; and CP 97‐2103 and CP 92‐1167 for CP 09‐4758. Averaged across three crop cycles, CP 09‐4153 and CP 09‐4758 had, respectively, 32.4 and 21.9% higher cane yield and 28.1 and 20.2% higher sucrose yield compared with ‘CL 88‐4730’, a commercial reference cultivar. CPCL 09‐4160 did not differ significantly from CL 88‐4730 in cane and sucrose yields, but it was resistant to major sugarcane diseases in the region except ratoon stunt. CP 09‐4153 and CP 09‐4758 were considered to have low to moderate freeze tolerance while CPCL 09‐4160 was considered to be moderate in freeze tolerance. Overall, these three cultivars were released by the Florida Sugarcane Variety Committee due to their high cane and sucrose yields, particularly in the ratoon crops, and their acceptable levels of resistance to brown rust, orange rust (except CP 09‐4758), smut, leaf scald (except CP 09‐4758), Sugarcane mosaic virus strain E, ratoon stunt (except CPCL 09‐4160), and Sugarcane yellow leaf virus.

English

Agriculture suffers considerable losses in its production caused by plant diseases. In the citrus culture some problems were associated with citrus canker caused by Xanthomonas citri subsp. citri. That same way, sugarcane plantations are impaired to leaf scald disease caused by Xanthomonas albilineans. One of the measures used to contain citrus canker is the spray of cupric bactericides; however for scalding leaves there are no satisfactory control. Due to the phytosanitary problem caused by Xanthomonas (X. citri and X. albilineans) and by the difficulty of its control, the search for new forms of defense, less harmful to the environment, has become increasingly required. Thus, the aim of this work was to obtain crude organic extracts from filamentous fungi isolated from Antarctic soil samples and assess its bioactivity potential against X. citri and X. albilineans. One hundred and twenty-two extracts were tested, seven extracts inhibited the cell growth of X. citri, one was bioactive only against X. albilineans and one extract inhibited the cell growth of both bacteria. The bioactive extracts had a mean inhibition value of 96% against both bacteria. The values of MIC90 and MBC of bioactive extracts were also determined; for X. citri the isolate 3.1 Fe presented the lowest values of MIC90 (0.28 mg/mL) and MBC (1.0 mg/mL) and the two bioactive isolates for X. albilineans (1.1-Fe and B-Fe) presented the same values of MIC90 (1.4 mg/mL) and MBC (1.5 mg/mL). The filamentous fungi that produced positive extracts were identified as belonging to the genus Pseudogymnoascus (n=8) and Cladosporium (n=1). The filamentous fungi isolated from Antarctic soil produced compounds with bioactivity against phytopathogens from the Xanthomonas genus. Key words: Antarctic fungi; antibacterial action; citrus canker; leaf scald; natural extracts.

Spring barley variety Laudis 550

Laudis 550 is a mid-late malting spring barley variety, medium resistant to lodging and medium resistant to stem brackling. It is resistant to powdery mildew, medium resistant to brown rust, leaf blotch complex and scald. The variety reached 7.2 points of the malting quality index (to the registration date) and it is recommended by the Research Institute of Brewing and Malting, Plc for production of beer with the protected geographical indication České pivo (Czech beer).

Identification and Phylogenetic Analysis of Xanthomonas albilineans (Ashby) Dowson Based on Multiple Gene Sequences in Yunnan Province, China

Sugarcane leaf scald caused by Xanthomonas albilineans (Ashby) Dowson is an extremely destructive disease. In 2017, suspected symptoms of sugarcane leaf scald was observed, in Baoshan, Mengding and Jinping, Yunnan Province, China. The bacteria was isolated from the symptomatic stalks and was subsequently identified as the causal agent using Koch’s postulates. BLASTN analysis showed that the amplified nucleotide sequences of 16S rRNA, gyrB and rpoD genes from all isolates shared 100% sequence identity with the nucleotide sequences of corresponding genes of X. albilineans strain GPE PC73 (Acc no. FP565176). Based on symptom diagnosis in the field, colony morphology, validation of Koch’s postulates and molecular identification of 16S rRNA, gyrB and rpoD genes, the disease was confirmed as sugarcane leaf scald caused by X. albilineans. Partial 16S rRNA, gyrB and rpoD gene sequence analysis of 36 X. albilineans strains from Yunnan and Guangxi provinces, China, was determined. The results revealed that the gyrB gene was the most sensitive in differentiating X. albilineans strains from Yunnan and Guangxi provinces.

Rhynchosporium leaf scald disease incidence: seed source and spatial pattern

A programme of field trials for the study of the winter barley–Rhynchosporium commune pathosystem is reported. The associated seedborne disease rhynchosporium leaf scald is regarded as having an important impact on barley yields. The analysis in this study relates to the impact of the seed source (commercial or farm‐saved seed) on disease incidence and to the spatial pattern of rhynchosporium leaf scald disease incidence. Disease incidence data were calculated from field data recorded as disease severity. Mean disease incidence was higher in the crops grown from farm‐saved seed than in those grown from commercial seed, although great agronomic significance cannot be attached to this result. The spatial pattern of rhynchosporium leaf scald disease incidence was characterized in terms of the binary power law (BPL) and was indicative of an aggregated pattern. Programme‐wide BPL results were described using a novel phytopathological application of a random coefficients model. These results have application in field sampling for rhynchosporium leaf scald disease.

Detection of sugarcane leaf scald from latent infections

Leaf scald is one of the major bacterial diseases affecting sugarcane crop. Previous studies have reported the difficulty detection of the pathogen by conventional PCR when applied in asymptomatic plant material, where the pathogen population level is find below the detectable limit by conventional PCR. Because of this factor and the resilience of Xanthomonas albilineans at latent stage, our study aimed to enhance protocols, both extraction pro­cedures of sugarcane juice and DNA extraction protocols from sugarcane juice for the detection of Xanthomonas albilineans even when the residual bacterial sample is minimal. We tested four techniques for sugarcane juice extraction: compressor, pressing, macerated and bacterial flow in water and four DNA extraction protocols, two of them considered quick or simple, a CTAB procedure and one commercial Kit. The results indicated that conven­tional PCR was not able to detect the pathogen in asymptomatic stalks. However, working on Nested-PCR, we could detect X. albilineans in latently infected plants in 100% of samples when the vascular fluid was extracted by bacterial water flow following a centrifugation, adding TAE and boiling as DNA extraction method.

Genome-wide Association Studies and Candidate Gene Identification for Leaf Scald and Net Blotch in Barley (Hordeum vulgare L.).

We report genomic regions that significantly control resistance to scald, net form (NFNB) and spot form net blotch (SFNB) in barley. Barley genotypes from Ethiopia, ICARDA, and the United States were evaluated in Ethiopia and North Dakota State University (NDSU). Genome-wide association studies (GWAS) were conducted using 23,549 single nucleotide polymorphism (SNP) markers for disease resistance in five environments in Ethiopia. For NFNB and SFNB, we assessed seedling resistance in a glasshouse at NDSU. A large proportion of the Ethiopian landraces and breeding genotypes were resistant to scald and NFNB. Most of genotypes resistant to SFNB were from NDSU. We identified 17, 26, 7, and 1 marker-trait associations (MTAs) for field-scored scald, field-scored net blotch, greenhouse-scored NFNB, and greenhouse-scored SFNB diseases, respectively. Using the genome sequence and the existing literature, we compared the MTAs with previously reported loci and genes for these diseases. For leaf scald, only a few of our MTAs overlap with previous reports. However, the MTAs found for field-scored net blotch as well as NFNB and SFNB mostly overlap with previous reports. We scanned the barley genome for identification of candidate genes within 250 kb of the MTAs, resulting in the identification of 307 barley genes for the 51 MTAs. Some of these genes are related to plant defense responses such as subtilisin-like protease, chalcone synthase, lipoxygenase, and defensin-like proteins.

Registration of ‘HoCP 09‐804’ Sugarcane

‘HoCP 09‐804’ (Reg. No. CV‐184, PI 688682) sugarcane (interspecific hybrid of Saccharum spp.) was selected and evaluated by the USDA‐ARS, working cooperatively with the Louisiana State University AgCenter and the American Sugarcane League, Inc. HoCP 09‐804 was selected from a cross between ‘HoCP 02‐625’ and ‘HoCP 01‐523’ made at the USDA‐ARS, Sugarcane Field Station, Canal Point, FL, in 2004 and was released to growers in Louisiana in 2016 because of high cane and sucrose yields. Yields from three crops (plant, first‐, and second‐ratoon) at 12 outfield locations compared well with ‘L 01‐299’, the most widely grown cultivar in Louisiana. The plant‐cane sugar yield (Mg ha−1) of HoCP 09‐804 was significantly greater than L 01‐299. The sucrose content (g kg−1) was second only to ‘HoCP 00‐950’, the standard for high sucrose. HoCP 09‐804 was among the earliest maturing cultivars, ranking second only to HoCP 00‐950, and cold tolerant, similar to ‘HoCP 04‐838’. HoCP 09‐804 is mildly susceptible to smut, leaf scald, and ratoon stunt. HoCP 09‐804 is susceptible to brown rust and mosaic caused by Sorghum mosaic virus. It is moderately susceptible to sugarcane borer. This cultivar's high yield potential, ratooning ability, and cold tolerance make it a useful addition to existing commercial sugarcane cultivars in Louisiana.

Registration of ‘CP 09‐2392’ Sugarcane

‘CP 09‐2392’ (Reg. No. CV‐182; PI 688299) sugarcane, a complex hybrid of Saccharum spp., was developed through cooperative research conducted by the USDA–ARS, the University of Florida, and the Florida Sugarcane League, Inc., and was released to growers in June 2016. CP 09‐2392 was selected from a cross made at the USDA–ARS Sugarcane Field Station in Canal Point, FL, in December 2007. The female parent was ‘CP 01‐2390’; the identity of the male parent is difficult to determine as the cross included multiple potential male parents, i.e., a polycross. CP 09‐2392 was superior to the reference cultivar ‘CL 88‐4730’ on sand soils with regard to stalk weight, cane yield, commercial recoverable sucrose (a measure of sucrose content), sucrose yield, and economic index (i.e., overall profitability). CP 09‐2392 is resistant to brown rust, leaf scald, ratoon stunt, Sugarcane mosaic virus strain E (mosaic), smut, and Sugarcane yellow leaf virus and is moderately resistant to orange rust. In addition, CP 09‐2392 has good freeze tolerance. This cultivar is recommended for mineral (sand) soils in Florida.

Analysis of Analysis of Agronomic Traits and Quarantine Diseases of Sugarcane Germplasms Newly Introduced from USA and Vietnem

The purpose of this study was to detect the status of Fiji disease virus (FDV) and leaf scald ( Xanthomonas albilineans ) in the newly introduced sugarcane germplasms from USA and Vietnam, and observe their agronomic performances in Guangxi sugarcane growing area, thus to provide references for screening healthy sugarcane germplasm. Following the quarantine procedure, 41 newly introduced sugarcane germplasm accessions were planted in isolated quarantine area for FDV and leaf scald detection. The PCR (RT-PCR) results showed the reaction to FDV and leaf scald were both negative and no quarantine disease occurred. Further, field experiments were conducted to observe their agronomic performance and resistance to commom diseases, like red rot, yellow spot, ring spot, pokkah boeng, mosaic, smut, rust and brown stripe diseases, and the results showed that 18 germplasm accessions were resistant to these diseases. Based on the experimental results, 8 accessions from USA and 4 accessions from Vietnam were selected for the next variety test. This study would provide excellent resistant germplasm materials and scientific references for further sugarcane disease resistance breeding.