Association of a monopartite begomovirus and associated betasatellite with yellow vein disease of a weed host, Senna italica Mill. In Oman.

Senna italica Mill. plants exhibiting yellowing and stunting symptoms typical of begomovirus infection were collected in Oman. Molecular characterization using begomovirus and betasatellite primers in polymerase chain reaction followed by rolling circle amplification, cloning and analysis of sequences revealed the S. italica plants were infected by an isolate of Chilli leaf curl virus and tomato leaf curl betasatellite. The study describes the etiology of a yellow vein disease, identified for the first time, affecting a common weed in Oman.

Witches' Broom Disease of Lime Contributes to Phytoplasma Epidemics and Attracts Insect Vectors.

An insect-transmitted phytoplasma causing Witches' Broom Disease of Lime (WBDL) is responsible for the drastic decline in lime production in several countries. However, it is unclear how WBDL phytoplasma (WBDLp) induces witches' broom symptoms and if these symptoms contribute to the spread of phytoplasma. Here we show that the gene encoding SAP11 of WBDLp (SAP11WBDL) is present in all WBDLp isolates collected from diseased trees. SAP11WBDL interacts with acid lime (Citrus aurantifolia) TCP transcription factors, specifically members of the TB1/CYC class that have a role in suppressing axillary branching in plants. Sampling of WBDLp-infected lime trees revealed that WBDLp titers and SAP11WBDL expression levels were higher in symptomatic leaves compared with asymptomatic sections of the same trees. Moreover, the witches' brooms were found to attract the vector leafhopper. Defense genes that have a role in plant defense responses to bacteria and insects are more downregulated in witches' brooms compared with asymptomatic sections of trees. These findings suggest that witches' broom-affected parts of the trees contribute to WBDL epidemics by supporting higher phytoplasma titers and attracting insect vectors.

Frequent occurrence of Mungbean yellow mosaic India virus in tomato leaf curl disease affected tomato in Oman.

Next generation sequencing (NGS) of DNAs amplified by rolling circle amplification from 6 tomato (Solanum lycopersicum) plants with leaf curl symptoms identified a number of monopartite begomoviruses, including Tomato yellow leaf curl virus (TYLCV), and a betasatellite (Tomato leaf curl betasatellite [ToLCB]). Both TYLCV and ToLCB have previously been identified infecting tomato in Oman. Surprisingly the NGS results also suggested the presence of the bipartite, legume-adapted begomovirus Mungbean yellow mosaic Indian virus (MYMIV). The presence of MYMIV was confirmed by cloning and Sanger sequencing from four of the six plants. A wider analysis by PCR showed MYMIV infection of tomato in Oman to be widespread. Inoculation of plants with full-length clones showed the host range of MYMIV not to extend to Nicotiana benthamiana or tomato. Inoculation to N. benthamiana showed TYLCV to be capable of maintaining MYMIV in both the presence and absence of the betasatellite. In tomato MYMIV was only maintained by TYLCV in the presence of the betasatellite and then only at low titre and efficiency. This is the first identification of TYLCV with ToLCB and the legume adapted bipartite begomovirus MYMIV co-infecting tomato. This finding has far reaching implications. TYLCV has spread around the World from its origins in the Mediterranean/Middle East, in some instances, in live tomato planting material. The results here may suggest that begomoviruses which do not commonly infect tomato, such as MYMIV, could be spread as a passenger of TYLCV in tomato.

Families of Diaporthales based on morphological and phylogenetic evidence.

Diaporthales is an important ascomycetous order comprising phytopathogenic, saprobic, and endophytic fungi, but interfamilial taxonomic relationships are still ambiguous. Despite its cosmopolitan distribution and high diversity with distinctive morphologies, this order has received relativelyiaceae, Macrohilaceae, Melanconidaceae, Pseudoplagiostomaceae, Schizoparmaceae, Stilbosporaceae and Sydowiellaceae. Taxonomic uncertainties among genera are also clarified and recurrent discrepancies in the taxonomic position of families within the Diaporthales are discussed. An updated outline and key to families and genera of the order is presented.

Analysis of bacterial communities associated with potting media.

BACKGROUND: Potting media are commonly used by growers in different parts of the world for potted plants, raising seedlings and for improving soil characteristics. This study was conducted to characterize bacterial communities occurring in 13 commercial potting media products originating from seven countries. FINDINGS: Bacteria were isolated using serial dilution. Identification to the species level was based on phylogenetic analysis of the 16S rRNA gene. The analysis showed the association of 13 bacterial species with the different potting media samples, namely Arthrobacter livingstonensis, Kocuria flava, Leifsonia lichenia, Bacillus vallismortis, Bacillus pumilus, Staphylococcus warneri, Burkholderia phenazinium, Burkholderia sp., Ralstonia pickettii, Rhodanobacter spathiphylli, Rhodanobacter sp., Pseudomonas thivervalensis and Chryseobacterium gallinarum. Bacterial densities in the samples ranged from 8 × 10(7) to 1.2 × 10(9) colony forming units per gram of substrate. CONCLUSIONS: The study shows the isolation of some potential plant and human bacterial pathogens. However, most of the isolated species were either biocontrol species or saprophytes. The study questions the ways by which these bacterial species were introduced into potting media. To the best of our knowledge, this appears to be the first report of most of the isolated bacteria from potting media, except B. pumilus.

Evaluation of culture-based techniques and 454 pyrosequencing for the analysis of fungal diversity in potting media and organic fertilizers.

AIMS: Potting media and organic fertilizers (OFs) are commonly used in agricultural systems. However, there is a lack of studies on the efficiency of culture-based techniques in assessing the level of fungal diversity in these products. A study was conducted to investigate the efficiency of seven culture-based techniques and pyrosequencing for characterizing fungal diversity in potting media and OFs. METHODS AND RESULTS: Fungal diversity was evaluated using serial dilution, direct plating and baiting with carrot slices, potato slices, radish seeds, cucumber seeds and cucumber cotyledons. Identity of all the isolates was confirmed on the basis of the internal transcribed spacer region of the ribosomal RNA (ITS rRNA) sequence data. The direct plating technique was found to be superior over other culture-based techniques in the number of fungal species detected. It was also found to be simple and the least time consuming technique. Comparing the efficiency of direct plating with 454 pyrosequencing revealed that pyrosequencing detected 12 and 15 times more fungal species from potting media and OFs respectively. Analysis revealed that there were differences between potting media and OFs in the dominant phyla, classes, orders, families, genera and species detected. Zygomycota (52%) and Chytridiomycota (60%) were the predominant phyla in potting media and OFs respectively. CONCLUSIONS: The superiority of pyrosequencing over cultural methods could be related to the ability to detect obligate fungi, slow growing fungi and fungi that exist at low population densities. SIGNIFICANCE AND IMPACT OF THE STUDY: The evaluated methods in this study, especially direct plating and pyrosequencing, may be used as tools to help detect and reduce movement of unwanted fungi between countries and regions.

First Report of Tomato leaf curl Albatinah virus (ToLCABV) and its Associated Betasatellite Infecting Papaya in Oman.

Leaf curl disease with severe curling, vein darkening, and vein thickening was observed on papaya plants in a field in Qurayat district of Oman during December 2013. Disease incidence ranged from 50 to 70%, particularly in young papaya plants. The presence of a large population of whiteflies and symptoms observed on papaya plants suggested that the causal agent could be begomoviruses (family Geminiviridae) and associated satellites. Four leaf samples with mild and severe leaf curling were collected from the field. Total nucleic acid extracted from symptomatic and healthy plants using the CTAB method were used as a template to amplify circular DNAs using Φ29 DNA polymerase, and products were digested with restriction enzymes to identify fragments of 2.6 to 2.8 kb typical of geminiviruses. BamHI yielded fragments of ~2.8 and 1.4 kb when the digested products were resolved by electrophoresis on a 1% agarose gel. These fragments were cloned and sequenced using a primer walking strategy in both directions. Sequencing results confirmed the exact sizes of 1,303, 1,358, and 2,765 bp; the sequences were deposited in GenBank under the accession numbers HG969296, HG969297, and HG969260, respectively. BLAST results showed that the first two sequences are Tomato leaf curl betasatellite (ToLCB; isolates Pap-2 and Pap-3) showing 97% sequence identity with a previously reported ToLCB sequence (Accession No. KF229728). Both satellites encode a single gene in the complementary sense strand referred to as ßC1, which showed 97% sequence identity to ToLCB (HE800551). The viral sequence (isolate Pap-6) showed four genes in the complementary sense (the replication-associated protein [Rep] gene, the transcription-activator protein [TrAP] gene, the replication-enhancer protein [REn] gene, and the C4 gene) and two genes (pre-coat protein [V2] and coat protein [CP]) in virion-sense (2). BLAST analysis showed 95.2% sequence identity to Tomato leaf curl Albatinah virus (ToLCABV; FJ956700), reported earlier to infect tomato in Oman (3). Amino acid sequence comparison of the four predicted proteins (Rep, TrAP, Ren, and C4) encoded by Pap-6 shared 95, 96, 100, and 100% sequence identity, whereas virion-sense proteins (V1 and V2) shared 99% sequence identity with ToLCABV (FJ956700). According to the recommendations of the International Committee on Taxonomy of Viruses, these results indicate that the virus identified in association with papaya leaf curl disease in Oman is a variant of ToLCABV (1). All infected samples showed the presence of ToLCABV, while no hybridization was observed in healthy control DNA using ToLCABV probe. These findings are indicative of the rapid spread of diseases involving Begomovirus and betasatellites, which often result in increased host range, as is evident from this study. References: (1) C. M. Fauquet et al. Arch. Virol. 148:405, 2003. (2) L. Hanley-Bowdoin et al. Crit. Rev. Plant Sci. 18:71, 1999. (3) A. J. Khan et al. Arch. Virol. 159:445, 2013.

First Report of Root Rot and Crown Necrosis Caused by Pythium aphanidermatum on Phaseolus vulgaris in Oman.

In March 2013, 90% of mature bean plants (Phaseolus vulgaris L. cv. Kendo) grown on a commercial farm in the north of Oman (Barka) developed symptoms of root rot and necrotic streaks on the crown area of the stem and wilted. A Pythium spp. was isolated consistently from roots and basal stems on 2.5% potato dextrose agar (PDA) and V8 (100% vegetable juice) plus 1.5% agar technical. Colonies of Pythium spp. on PDA and V8 plus agar developed abundant aerial mycelia, with the main hyphae being up to 10 µm wide. Zoosporangia were made up of terminal complexes of swollen hyphal branches of different lengths and up to 22 µm wide. Oogonia were terminal, globose, and smooth with a 26-µm diameter (average of 20). Antheridia were mostly intercalary, sometimes terminal, and broadly sac-shaped, 15 µm long and 11 µm wide (average of 20). Oospores were aplerotic, 23 µm in diameter (average of 24), with walls 1 to 2 µm thick at 25°C (ambient temperature). The internal transcribed spacer of the ribosomal DNA (ITS1 and ITS4) sequence of the isolates matched the sequence of Pythium aphanidermatum (Edson) Fitzp. in GenBank. The sequence of isolate Py1 was deposited in GenBank as Accession No. KM102739. This isolate was identified as P. aphanidermatum on the basis of morphological and cultural characteristics (1) and the ITS rDNA sequence. The ITS was found to share 100% nucleotide similarity to previously published sequences of the ITS (KJ755088). To fulfill Koch's postulate, a 5-mm plug of 5-day-old mycelium of isolate Py1 grown on 2.5% PDA was used to inoculate healthy seedlings of beans cv. Kendo. The plug was placed adjacent to the bean stem; PDA served as a control. Five replicate plants were used for the treatment and the control. The plants were maintained in a glasshouse at a temperature of 23 to 25°C. The plants were watered every day. The irrigation water had an electrical conductivity value of 0.2 dSm-1. Eleven days after inoculation, 90% of the plants developed root rot, crown necrosis, and wilt symptoms similar to those observed in the field. On the other hand, control plants did not show any symptoms. The pathogen was re-isolated from roots and basal stems of symptomatic plants. To our knowledge, this is the first report of P. aphanidermatum as the causal agent of root and crown necrosis of mature bean plants in Oman. Future studies should focus on evaluating management options for this disease to avoid possible losses in a crop that has a high export value in Oman. Reference: (1) Y. Serrano et al. Plant Dis. 92:174, 2008.

Intraspecific and intragenomic variability of ITS rDNA sequences reveals taxonomic problems in Ceratocystis fimbriata sensu stricto.

Fourteen new species in the Latin American Clade (LAC) of the Ceratocystis fimbriata complex recently were distinguished from C. fimbriata sensu stricto largely based on variation in ITS rDNA sequences. Among the 116 isolates representing the LAC, there were 41 ITS haplotypes. Maximum parsimony (MP) analysis of ITS sequences produced poorly resolved trees. In contrast, analyses of mating-type genes (MAT1-1-2 and MAT1-2-1) resolved a single MP tree with branches of high bootstrap and posterior probability support. Four isolates showed intragenomic variation in ITS sequences. Cloning and sequencing of PCR products from a single haploid strain identified two or more ITS sequences differing at up to 16 base positions and representing two described species. Isolates from introduced populations that appeared to be clonal based on microsatellite markers varied at up to 14 bp in ITS sequence. Strains of seven Brazilian ITS haplotypes and an isolate from Ipomoea batatas (on which the species name C. fimbriata was based) were fully interfertile in sexual crosses. These analyses support three phylogenetic species that differ in pathogenicity: C. platani, C. cacaofunesta and C. colombiana. Five ITS species (C. manginecans, C. mangicola, C. mangivora, C. acaciivora, C. eucalypticola) appear to be ITS haplotypes that have been moved from or within Brazil on nursery stock. The taxonomic status of other species delineated primarily by ITS sequences (C. diversiconidia, C. papillata, C. neglecta, C. ecuadoriana, C. fimbriatomima, C. curvata) needs further study, but they are considered doubtful species.

First Report of a 16SrII-C Phytoplasma Associated with Asymptomatic Acid Lime (Citrus aurantifolia) in Brazil.

At present, the principal bacterial disease of citrus in Brazil is Huanglongbing, caused by the alpha-proteobacterium 'Candidatus Liberibacter spp.' (although a phytoplasma of the 16SrIX group is also associated with this disease [4]). While there is a wide diversity of phytoplasmas in crop species in Brazil (3), there have been no reports of symptoms associated with phytoplasma in Brazilian citrus. Asymptomatic infections of citrus cannot be excluded as a possibility and such plants could serve as a reservoir of phytoplasma inoculum. The aim of this study was to assess the presence of phytoplasma in asymptomatic Citrus aurantifolia (acid lime) in Brazil. Thirty-three leaf samples (young leaves from the upper canopies) were randomly collected from different plants in the states of Minas Gerais (n = 23), Santa Catarina (n = 2), and São Paulo (n = 8). Two additional samples of C. limonia ('Rangpur' lime) and one of C. latifolia ('Persian' or 'Tahiti' lime) were collected in Minas Gerais. Total DNA extraction was performed using NucleoSpin Plant II Kit (Macherey-Nagel) according to the manufacturer's recommendations. PCR was carried out with a universal P1/P7 primer set followed by nested primers R16F2n/R16R2 (2). Additionally, direct PCR was performed using primers specific for phytoplasma immune-dominant membrane protein IMP3F/IMP3R (1). 'Rangpur' and 'Tahiti' lime were not infected with phytoplasma. Of the C. aurantifolia samples, 52% were positive for phytoplasma in the direct and nested PCR assays. The numbers of positive samples in Minas Gerais, Santa Catarina, and São Paulo states were 12, 1, and 4, respectively. Of these, five were selected for DNA purification and 1,246-bp fragments were ligated to the pGEM T-easy vector (Promega) and partial 16Sr DNA was sequenced. Nucleotide sequences of Brazilian phytoplasma strains BR:MG:FNS10:2011, BR:MG:FNS53:2011, BR:SP:FNS73:2011, BR:SC:FNS86:2011, and BR:MG:FNS126:2012 (GenBank Accession Nos. KJ158173, KJ158174, KJ158175, KJ158176, and KJ158177, respectively) were subjected to RFLP analyses. The 16S rDNA RFLP in silico patterns for the five strains were identical to each other and to Cactus witches'-broom phytoplasma (16SrII-C subgroup, AJ293216). In addition, the highest similarity coefficient (5) and nucleotide sequence identity of Brazilian phytoplasma strains were 0.99 and 99%, respectively, with Cactus witches'-broom phytoplasma. PCR-RFLP analyses using the enzymes Bstu I, EcoR I, and Hpa II were consistent with RFLP in silico results, showing the same pattern as the 16SrII-C subgroup. Phylogenetic analyses based on 16S rDNA sequences (1,246 bp) demonstrated that all the Brazilian strains grouped in the same clade with other representative sequences from the 16S rDNAII group. To confirm the absence of any macroscopic symptoms, morphological characteristics of 10 uninfected and 10 phytoplasma-infected plants randomly selected from a single field in Minas Gerais were analyzed. There were no significant differences in leaf area, stalk diameter, or numbers of leaves, flowers, or fruits per branch. To our knowledge, this is the first report of the 16SrII-C subgroup phytoplasma associated with C. aurantifolia in Brazil, and the first report of asymptomatic citrus plants infected with phytoplasma. References: (1) N. Askari et al. J. Microbiol. Biotechnol. 21:81, 2011. (2) I. M. Lee et al. Phytopathology 84:559, 1994. (3) H. G. Montano et al. Bull. Insectol. 60:129, 2007. (4) D. C. Teixeira et al. Phytopathology 98:977, 2008. (5) Y. Zhao et al. Meth. Mol. Biol. 938:329, 2013.

Population Genetic Analysis Reveals Diversity in Lasiodiplodia Species Infecting Date Palm, Citrus, and Mango in Oman and the UAE.

Lasiodiplodia is a common pathogen causing dieback, gummosis, or root necrosis on the three most important fruit crops in Oman and the United Arab Emirates (UAE): date palm (Phoenix dactylifera), Citrus spp., and mango (Mangifera indica). A study was conducted to examine diversity in 64 Lasiodiplodia isolates infecting date palm (24), Citrus (11), and mango (29) in Oman and the UAE. Identification based on sequences of the internal transcribed spacer (ITS) rDNA and EF1α gene showed that date palm isolates belonged to L. hormozganensis (75% of isolates) and L. theobromae (25%); Citrus isolates belonged to L. hormozganensis (45%), L. theobromae (45%), and L. iraniensis (10%); and mango isolates belonged to L. theobromae (59%), L. iraniensis (34%), and L. hormozganensis (7%). Amplified fragment length polymorphism (AFLP) fingerprinting of the 64 isolates using four primer pair combinations produced 64 genotypes and 972 polymorphic alleles. Cluster analysis separated the isolates into four clusters representing the three species. A higher level of genetic diversity was observed in L. iraniensis (0.3105) compared to L. hormozganensis (0.2503) and L. theobromae (0.2331) in Oman. Analysis of molecular variance (AMOVA) indicated the existence of low levels of genetic differentiation among date palm populations of L. hormozganensis obtained from Oman and the UAE (FST = 0.025) and among populations of L. hormozganensis (0.0485) and L. theobromae (0.0703) from date palm, Citrus, and mango. These findings imply a high rate of movement of L. hormozganensis and L. theobromae isolates among date palm, Citrus, and mango and between the two countries. Findings from the pathogenicity test supported the AMOVA analysis and suggested a lack of host specialization in L. hormozganensis, L. iraniensis, and L. theobromae on date palm, acid lime, and mango. Although this is the first record of L. hormozganensis and L. iraniensis in Oman, the relatively moderate level of genetic diversity in the two species compared to L. theobromae suggests that the two species have been in Oman for a long time but misidentified by morphology and ITS rDNA sequences as L. theobromae. This study is also the first record of date palm and acid lime as natural hosts for L. hormozganensis and the first record of L. hormozganensis in the UAE. The diversity in Lasiodiplodia species affecting date palm, Citrus, and mango in Oman and the UAE should be taken into consideration when planning future management programs for diseases caused by these pathogens.

First Report of Euphorbia larica Dieback Caused by Fusarium brachygibbosum in Oman.

Euphorbia larica Boiss. (Arabic = Isbaq) is a dominant and common component of the native desert flora of northern Oman. Traditional ethnobotanical uses have included use of the latex for treating camels with parasites. In February 2011, E. larica plants showing stem lesions up to several cm long and in many cases with stem dieback were collected from Al-Khoudh 50 km west of Muscat. The disease appeared widespread within the location where several dead specimens were also recorded, although the cause was unclear. Sections (5 mm) of five diseased branches taken from different plants and placed on potato dextrose agar (PDA) in all cases yielded Fusarium-like colonies. Colonies recovered were initially white becoming rose to medium red in color with abundant aerial mycelium. Macroconidia were scarce and scattered (mean of 20 spores: 26.83 × 4.73 µm) with three to four septa per spore; microconidia were slightly curved, ovoid, and fusiform (mean of 20 spores: 11.64 × 4.03 µm) with zero to two septa per spore. Spherical chlamydospores (mean of 20 spores: 11.05 µm) were terminal and intercalary, single, and in chains. In vitro characters and spores measurements conformed to previously described features of Fusarium brachygibbosum Padwick (1). Mycelial plugs (5 mm) were taken from 7-day-old cultures of the fungus grown on 2.5% PDA and applied to a small incision (3 mm) on the stems of healthy E. larica grown in situ and protected with wet cotton and Parafilm. The residual agar, mycelium, cotton, and Parafilm were removed after 7 days and symptoms were recorded. Control stems were inoculated using PDA (5 mm) plugs alone and inoculations were repeated twice. Artificial inoculations resulted in dieback of all stems within 11 days and fungal colonies identical to initial isolations were recovered from artificially infected surface-sterilized stem pieces. Identification of F. brachygibbosum was confirmed by comparing sequences generated from the internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1 and ITS4 primers) and the intron region of translation elongation factor alpha (EF1-α) (EF-1-986 and EF-728 primers). The ITS and EF1-α sequences were found to share 100% and 99% nucleotide similarity to previously published sequences of the ITS (HQ443206) and EF1-α (JQ429370) regions of F. brachygibbosum in GenBank. The accession number of ITS sequence of one isolate assigned to EMBL-Bank was HF562936. The EF sequence was assigned to EMBL-Bank accession (submission number Hx2000027017; number will be sent later). This pathogen has previously been reported on date palm (2) in Oman but, to our knowledge, this is the first report of this pathogen on E. larica. References: (1) A. M. Al-Sadi et al. Crop Prot. 37:1, 2012. (2) G. W. Padwick. Mycol. Pap. 12:11, 1945.

Analysis of Diversity in Pythium aphanidermatum Populations from a Single Greenhouse Reveals Phenotypic and Genotypic Changes over 2006 to 2011.

A study was conducted to investigate phenotypic and genotypic changes within Pythium aphanidermatum populations during the period 2006 to 2011. In total, 92 isolates of P. aphanidermatum (59 in 2006 and 33 in 2011) were obtained from different planting sites (soil) of cucumber from a single greenhouse. Generated sequences of the internal transcribed spacer (ITS) ribosomal DNA showed that all, except one isolate, share an identical sequence of the ITS region. Most (89%) P. aphanidermatum isolates were found to be aggressive on cucumber seedlings, with no significant differences in the aggressiveness level between populations obtained from different planting rows or different years. Sensitivity to metalaxyl among populations of P. aphanidermatum increased significantly from concentration resulting in 50% growth inhibition levels of 0.070 to 1.823 (average 0.824 µg ml-1) in 2006 to 0.002 to 0.564 (average 0.160 µg ml-1) in 2011. Amplified fragment length polymorphism analysis of the 92 isolates produced 92 different genotypes and 985 polymorphic loci. P. aphanidermatum populations from 2006 and 2011 were found to have low levels of genetic diversity (H = 0.1425), which implies introduction of the isolates into the greenhouse via common sources. Results from analysis of molecular variance (FST = 0.0307 in 2006 and 0.0222 in 2011) provided evidence for frequent exchange of Pythium inoculum between different planting locations within the same year. However, the analysis showed moderate levels (FST = 0.1731) of genetic differentiation among populations from the 2 years. This was supported by unweighted pair group method with arithmetic means analysis, which showed clustering of many of the 2006 isolates in separate clusters. The change in the metalaxyl sensitivity of the populations from 2006 to 2011 accompanied by the genetic differences among these two populations may suggest that many of the isolates from 2006 were lost and were replaced by new and highly sensitive P. aphanidermatum isolates by 2011.

First Report of Rust Caused by Puccinia carthami on Safflower in Oman.

Safflower (Carthamus tinctorius L.) is a minor, but culturally important crop in Oman; the dried flowers produce a pigment used in facial ornamentation. Although Oman is not a commercial producer of safflower, the region is a center of diversity and a source of genetic material for breeding programs. Production of oil from safflower has potential in Oman, where plant growth is prolific. In April 2004, leaf samples showing rust symptoms were collected from Mudhaibi, 100 km south of Muscat. Chestnut brown pustules covered both sides of the leaves, but not the stems, and yielded urediniospores and teliospores typical of the pathogen. Urediniospores were globose, 25 µm in diameter with three germ pores. Two-celled teliospores were chestnut brown, minutely verrucose, with a single, depressed germ pore in each cell. The pathogen was identified as Puccinia carthami Corda (voucher specimen deposited in the U.S. National Fungus Collections, BPI863557; nuclear ribosomal large subunit DNA voucher sequence deposited in GenBank, Accession No. AY787782). On the basis of phylogenetic analyses, the rust from Oman belongs to a complex of closely related Puccinia spp. that infects members of the Cardueae. Elsewhere, in addition to leaf infections, P. carthami causes foot and root disease of safflower (1) with teliospores surviving in the soil and on seed to initiate new infections. Germplasm is now being collected and will be screened for variation in response to rust infection. Reference: (1) M. L. Schuster et al. Phytopathology 42:211, 1952.