Petiole Bases Research Articles

A correlation between leaf shape and its related key genes in Viola albida complex

Simple to compound leaves occur in the Viola albida complex, which comprises the simple, finely serrate leaves of V. albida Palib., the deeply lobed leaves of V. albida var. takahashii (Nakai) Nakai, and the compound leaves of Viola chaerophylloides (Regel) W. Becker. To identify a correlation between the different leaf forms and the expression of several key genes with roles in leaf morphogenesis, the distinct leaf forms occurring within these species were generated by tissue culture of the V. chaerophylloides petiole, for comparison with wild-type leaves. Compound leaves were generally formed from a petiole explant taken close to the leaf blade, whereas simple leaves resulted from petiole explants taken close to the petiole base. KNOTTED-1 (VaKN1), SHOOTMERISTEMLESS (VaSTM), CUP-SHAPED COTYLEDON-2 (VaCUC2), and ASYMMETRIC LEAVES 1 (VaAS1), which are known to play key roles during compound leaf patterning and morphogenesis, were isolated and multiple sequence alignment revealed that there was no sequence variation at the amino acid level within each gene and between the three varieties. Phylogenetic analysis confirmed that the isolated genes were homologous to KN, STM, CUC2, and AS1. The expression of VaKN1, VaSTM, and VaCUC2 was significantly elevated in the in vitro-cultured deeply lobed and compound leaves, as well as in V. chaerophylloides and V. albida var. takahashii plants, but was very low in the in vitro-cultured simple leaves and V. albida plants. These findings demonstrated that elevated transcripts of VaKN1, VaSTM, and VaCUC2 lead to the development of compound and deeply lobed leaves in the V. albida complex.

Primulina lianchengensis (Gesneriaceae), a new species from Danxia landform of Fujian, China: Evidence from morphological and molecular analyses

Primulina lianchengensis B.J.Ye & S.P.Chen (Gesneriaceae) is described and illustrated from Fujian Province in the Southeast of China. Then phylogenetic analyses of the genus were presented using nuclear ribosomal ITS and two plastid markers (atpB-rbcL and rpL32-trnL). Morphological analysis indicates that P. lianchengensis is similar to P. danxiaensis, P. depressa, P. lechangensis and P. yangshanensis, but it differs in the base and margin of leaf, petiole, bract, length and shape of corolla, numbers of staminodes and stigma lobe. Molecular analysis reveals that P. lianchengensis is genetically similar to P. danxiaensis and P. yangshanensis.

Phylogenetic relationships of Neotropical lady ferns (Athyriaceae), with a description of Ephemeropteris, gen. nov.

We carried out a molecular phylogenetic analysis of Neotropical lady ferns (Athyrium s.str. and Anisocampium) using five plastid markers. We found two major results. First, three Neotropical species (Anisocampium skinneri, Athyrium palmense, A. tejeroi) formed a clade, and this clade was sister to the rest of Athyrium. The three members of this clade differ from Athyrium s.l. by creeping rhizomes with internodes 1–2 mm long, and rhizome apices that protrude beyond the current season's cluster of leaves. Also, the leaves are distichously arranged, lack trophopods, have petiole bases broadly U‐shaped in transverse section, and bear thin, membranous laminae. We recognize this clade as a new genus, Ephemeropteris, and provide three new combinations: E. palmensis, E. skinneri, and E. tejeroi. The name of the new genus is derived from the seasonal production of its leaves, which are produced during the wet season and die back (i.e., are ephemeral) at the beginning of the dry season. Ephemeropteris is largely restricted to the Pacific side of Central America, a region that exhibits a marked dry season from November to May. We provide a key to the seven genera (including Ephemeropteris) we now recognize in the Athyriaceae, and a taxonomic treatment of the three species of Ephemeropteris. The treatment includes descriptions, illustrations, nomenclatural data, specimens cited, and a dot‐distribution map. Our second major result from the phylogenetic analysis is that the remaining three Neotropical species of Athyrium s.str. are polyphyletic. One of our seven samples was resolved in the A. filix‐femina clade (sect. Athyrium), to which all species of Neotropical Athyrium were previously assumed to belong to. Our six other samples of Neotropical Athyrium were resolved in A. sect. Mackinnoniana, previously construed as entirely Asian.

First Report of Root Rot on Strawberry Caused by Binucleate Rhizoctonia AG-A in Spain

Strawberry (Fragaria × ananassa Duch.) is an important crop in Spain. In January 2018, ‘Florida Fortuna’ strawberry plants exhibiting poor growth were observed in a fruit production field in Palos de la Frontera, Huelva (southwestern Spain). These plants were from nurseries in Avila Province (Spain) that had soils with a high clay content. Affected plants showed varying degrees of stunting, black necrosis on basal petioles, brown to dark-brown discoloration in roots, and few new roots emerging from the crown. Two foci were found and surveyed (six plants per focus). Petiole, crown, and root pieces of symptomatic plants were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed in sterile distilled water, and air-dried in a laminar flow cabinet. Disinfested pieces were transferred to Petri dishes containing potato dextrose agar (PDA) and incubated for 7 days at 25°C. Five fungal isolates were recovered. Colonies were white to pale brown and had floccose aerial mycelia. Two isolates were purified by cutting hyphal tips from their margins. Microscopic examination showed morphological characters coinciding with Rhizoctonia (Sneh et al. 1991). Nuclear staining with acridine orange solution (20 μl/ml), prepared in acetic acid buffer, pH 7.2, for 15 min (Seema et al. 2012) showed two nuclei per cell in the hyphae of the two isolates. Mean hyphal diameter was 4.79 µm. No sclerotia were formed after 20 days on PDA at 25°C. The morphological characteristics of the isolates resembled those of binucleate Rhizoctonia (BNR). Species identity was confirmed for one isolate by sequencing the intergenic spacer (ITS) region of ribosomal DNA with the primers ITS1 and ITS4 (White et al. 1990). Identities of the resulting sequences were confirmed by BLAST analysis. The sequences were 100% identical to those of Ceratobasidium sp. AG-A KC782943 and were deposited as MH666073 in GenBank. Hyphal anastomosis tests were conducted by paring isolates with seven known tester isolates of BNR AG on 2% water agar. Anastomosis was observed with AG-A tester isolate. The isolates were identified as a BNR AG-A. To confirm the pathogenicity of the isolate, five runner strawberry plants ‘Rociera FNM’ and five ‘Rabida FNM’ were inoculated with PDA colonized plugs 1 cm in diameter located at the crown base. Five noninoculated plants were used as negative controls. Plants were grown in 200-ml pots with peat in a growth chamber at 25/22°C (day/night) with a 12-h photoperiod. Symptoms started appearing on inoculated plants 18 days after inoculation. All inoculated plants showed the same symptoms described above. Disease severity was scored as proportion of affected or senescent leaves. Inoculated ‘Rociera FNM’ plants showed 36% more affected leaves than noninoculated ones, while this difference in ‘Rabida FNM’ plants was 29%. Inoculated ‘Rociera FNM’ plants also had significantly lower dry weights (mean value: 3.91 g) than control plants (mean value: 8.02 g). The fungus was reisolated and confirmed to be Rhizoctonia sp. The BNR AG-A is one of the most common groups associated with root rot and a serious threat to strawberry production worldwide (Fang et al. 2013). To our knowledge, this is the first report of BNR AG-A causing root rot of strawberry in Spain. From now, growers will have to consider this pathogen for soil health management and for diseased plant diagnosis.

Development of a model to predict soybean yield loss from dicamba exposure

AbstractAlthough dicamba-resistant crops can provide an effective weed management option, risk of dicamba off-site movement to sensitive crops is a concern. Previous research with indeterminate soybean identified 14 injury criteria associated with dicamba applied at V3/V4 or R1/R2 at 0.6 to 280 g ae ha−1. Injury criteria rated on a 0 to 5 scale (none to severe), along with percent visible injury and plant height reduction, and canopy height collected 7 and 15 d after treatment (DAT) were analyzed using multiple regression with a forward-selection procedure to develop yield prediction models. Variables included in the 15 DAT models (in order of selection) for V3/V4 were lower stem base lesions/cracking, plant height reduction, terminal leaf epinasty, leaf petiole droop, leaf petiole base swelling, and stem epinasty, whereas for R1/R2 variables were lower stem base lesions/cracking, terminal leaf chlorosis, leaf petiole base swelling, stem epinasty, terminal leaf necrosis, and terminal leaf cupping. To validate the models, experiments including the same dicamba rates and application timings used in previous research were conducted at two locations. For the variables specific to each model, data collected for the dicamba rates were used to predict yield. For the V3/V4 15 DAT model, predicted yield reduction (compared with the nontreated control for dicamba at 0.6 to 4.4 g ha−1) underestimated or overestimated observed yield reduction by an average of 1 and 3 percentage points. For 8.8 g ha−1, predicted yield reduction overestimated observed yield reduction by 8 points and for 17.5 g ha−1 by 20 points. For the R1/R2 15 DAT model, predicted yield reduction for 0.6 to 4.4 g ha−1 overestimated observed yield reduction by an average of 3 to 5 percentage points. For dicamba at 8.8 g ha−1, predicted yield reduction underestimated observed yield reduction by 8 points and for 17.5 g ha−1 overestimated by 6 points.

First Report of Root Rot on Strawberry Caused by Binucleate Rhizoctonia AG-K in Spain

Strawberry (Fragaria × ananassa Duch.) is an important crop in Spain. In January 2018, ‘Florida Fortuna’ strawberry plants exhibiting poor growth were observed in a fruit production field in Palos de la Frontera, Huelva (southwestern Spain). These plants were from nurseries in Avila Province (Spain) that had soils with a high clay content. Affected plants showed varying degrees of stunting, black necrosis on basal petioles, brown to dark-brown discoloration in roots, and few new roots emerging from the crown. Two foci were found and surveyed (six plants per focus). Petiole, crown, and root pieces of symptomatic plants were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed in sterile distilled water, and air-dried in a laminar flow cabinet. Disinfested pieces were transferred to Petri dishes containing potato dextrose agar (PDA) and incubated for 7 days at 25°C. Five fungal isolates were recovered. Colonies were white to pale brown and had floccose aerial mycelia. Two isolates were purified by cutting hyphal tips from their margins. Microscopic examination showed morphological characters coinciding with Rhizoctonia (Sneh et al. 1991). Nuclear staining with acridine orange solution (20 μl/ml), prepared in acetic acid buffer, pH 7.2, for 15 min (Seema et al. 2012) showed two nuclei per cell in the hyphae of the two isolates. Mean hyphal diameter was 4.79 µm. No sclerotia were formed after 20 days on PDA at 25°C. The morphological characteristics of the isolates resembled those of binucleate Rhizoctonia (BNR). Species identity was confirmed for one isolate by sequencing the intergenic spacer (ITS) region of ribosomal DNA with the primers ITS1 and ITS4 (White et al. 1990). Identities of the resulting sequences were confirmed by BLAST analysis. The sequences were 100% identical to those of Ceratobasidium sp. AG-A KC782943 and were deposited as MH666073 in GenBank. Hyphal anastomosis tests were conducted by paring isolates with seven known tester isolates of BNR AG on 2% water agar. Anastomosis was observed with AG-A tester isolate. The isolates were identified as a BNR AG-A. To confirm the pathogenicity of the isolate, five runner strawberry plants ‘Rociera FNM’ and five ‘Rabida FNM’ were inoculated with PDA colonized plugs 1 cm in diameter located at the crown base. Five noninoculated plants were used as negative controls. Plants were grown in 200-ml pots with peat in a growth chamber at 25/22°C (day/night) with a 12-h photoperiod. Symptoms started appearing on inoculated plants 18 days after inoculation. All inoculated plants showed the same symptoms described above. Disease severity was scored as proportion of affected or senescent leaves. Inoculated ‘Rociera FNM’ plants showed 36% more affected leaves than noninoculated ones, while this difference in ‘Rabida FNM’ plants was 29%. Inoculated ‘Rociera FNM’ plants also had significantly lower dry weights (mean value: 3.91 g) than control plants (mean value: 8.02 g). The fungus was reisolated and confirmed to be Rhizoctonia sp. The BNR AG-A is one of the most common groups associated with root rot and a serious threat to strawberry production worldwide (Fang et al. 2013). To our knowledge, this is the first report of BNR AG-A causing root rot of strawberry in Spain. From now, growers will have to consider this pathogen for soil health management and for diseased plant diagnosis.

Simultaneous silencing of two target genes using virus-induced gene silencing technology in Nicotiana benthamiana.

Virus-induced gene silencing (VIGS) is an effective strategy for rapid gene function analysis. It is well established that the NAC transcription factor and salicylic acid (SA) signal pathway play essential roles in response to biotic stresses. However, simultaneous silencing of two target genes using VIGS in plants has been rarely reported. Therefore, in this report, we performed VIGS to silence simultaneously the SA-binding protein 2 (NbSABP2) and NbNAC1 in Nicotiana benthamiana to investigate the gene silencing efficiency of simultaneous silencing of two genes. We first cloned the full-length NbNAC1 gene, and the characterization of NbNAC1 was also analysed. Overlap extension polymerase chain reaction (PCR) analysis showed that the combination of NbSABP2 and NbNAC1 was successfully amplified. Bacteria liquid PCR confirmed that the combination of NbSABP2 and NbNAC1 was successfully inserted into the tobacco rattle virus vector. The results showed that the leaves from the NbSABP2 and NbNAC1 gene-silenced plants collapsed slightly, with browning at the base of petiole or veina. Quantitative real-time PCR results showed that the expression of NbSABP2 and NbNAC1 were significantly reduced in 12 days post silenced plants after tobacco rattle virus infiltration compared with the control plants. Overall, our results suggest that VIGS can be used to silence simultaneously two target genes.

Molecular identification and pathogenicity of Phytophthora nicotianae-caused bud rot disease of Washingtonia palms in Saudi Arabia and use of Lysobacter enzymogenes as a bioagent in an in vitro study

Severe terminal bud rot disease symptoms of Washingtonia, Washingtonia robusta, palms were observed in the 5-year-old trees in a farm located at the north of Al Shehia governorate, Qassim region, Saudi Arabia. The fungus found associated with the diseased palm buds was isolated in the laboratory, and pathogenicity tests were conducted on healthy 1-year-old Washingtonia palms, at an experimental station, Agriculture and Veterinary Medicine. Pathogenicity tests showed that a single fungus caused typical symptoms of bud rot on the inoculated trees. Petiole bases and terminal buds were rotted after 5–6 weeks of inoculation. The pathogen was identified through microscopy and characterized molecularly, using internal transcribed spacer (ITS) regions of ribosomal DNA, as a fungal-like organism Phytophthora nicotianae (synonym = P. parasitica). Experiments were conducted on the biological control of the pathogen in the laboratory, and a promising RN13 isolate of Lysobacter enzymogenes was selected for further study. This study seems to be the first report of bud rot disease of Washingtonian palms caused by P. nicotianae in Saudi Arabia. Great attention should be given to this disease because it is soil borne and may be transmitted to the date palm crop.

An efficient callus-based in vitro regeneration protocol for Warburgia Ugandensis Sprague, an important medicinal plant in Africa

Warburgia ugandensis Sprague is a woody species in the family Canellaceae and an important source of medicines in Africa. Natural propagation of W. ugandensis is problematic due to its recalcitrant seeds and lack of an efficient in vitro regeneration system for this species. This study describes an efficient regeneration protocol. Petiole bases and shoot tips were used as explants. Callus tissue developed when the explants were cultured on Murashige and Skoog medium containing 30 g L−1 sucrose and 7 g L−1 agar (MS30 medium), supplemented with 1.0 mg L−1 indole-3-butyric acid (IBA), 1.6 mg L−1 6-benzylaminopurine (BA), and 0.1 mg L−1 thidiazuron (TDZ). Adventitious buds were efficiently induced from the callus when the MS30 medium was supplemented with 0.8 mg L−1 BA and 0.2 mg L−1 IBA. Root induction occurred within 7–10 d on half-strength MS30 medium supplemented with 0.8–1.0 mg L−1 1-napthalene acetic acid (NAA), 0.2 mg L−1 IBA, and 0.03% (w/v) activated charcoal (AC). Roots were followed by root elongation on the same medium but lacking NAA and IBA. Approximately 50% of the plantlets cultured produced roots, while more than 80% of the plantlets survived and successfully grew to maturity.

<p><strong><em>Microtropis</em></strong><strong> <em>cerocarpa</em> (Celastraceae), a new species from southern Vietnam</strong></p>

Microtropis cerocarpa, a new species of Celastraceae, is described and illustrated. The species was discovered in 2012 during a botanical survey of the Chu Yang Sin National Park (Dak Lak province, southern Vietnam); additional collections were obtained there in 2018. Microtropis cerocarpa possesses dense glomerate sessile inflorescence with sessile flowers which allows placing this species into sect. Microtropis. Within this section it is most similar to M. obscurinervia, M. rhynchocarpa and M. wui. The new species differs from related species mainly by large thick leaves 23.5–39 cm long and 13–22 cm wide with very short petiole (subsessile) and cordate base, fruit with short rostrum of 1–2 mm long at apex, and immature fruit surface with a pronounced white wax coating in the form of granules. Microtropis cerocarpa is an easily recognized tree with remarkable robust habit and large leaves. A description of the vegetation in the area inhabited by M. cerocarpa is provided. The data on species diversity of Microtropis in Vietnam are summarized and an identification key is compiled.

Effects of ethylene and 1-MCP on quality maintenance of fresh cut celery

Ethylene is accepted to be a key player in the regulation of climacteric fruit ripening and senescence of leafy vegetables. In contrast, there is still disparity in the literature on the role it may have on quality deterioration of edible petioles. In this work, we evaluated the influence of the ethylene generator 2-chloroethylphosphonic acid (Ethephon) and the ethylene action inhibitor 1-methylcyclopropene (1-MCP) on quality maintenance of fresh cut celery. Commercially mature stalks from self-blanching celery cv. Golden Clause were cut into 2 cm-long slices. Samples from the apical and basal petiole zones were segregated and treated with 2000 mg L−1 2-chloroethylphosphonic acid or with 1 μL L−1 1-MCP. Corresponding slices without any treatment were used as control. Samples were packed and stored for 0, 6, 13 and 20 d at 4 °C and during this period celery visual deterioration (VD), respiration, weight loss and aerobic mesophilic bacteria, yeasts and molds counts were determined. Carotenoids, chlorophylls, phenolics, ascorbic acid, polyphenol oxidase (PPO), sugars, acidity, cell wall content and consumer acceptability were also evaluated. Ethylene had no major effects on weight loss, PPO, phenolic, sugars, acidity, and ascorbic acid. Instead, it increased respiration and accelerated chlorophyll degradation and surface yellowing. These changes were delayed in 1-MCP treated celery, which also maintained lower mesophilic bacteria and yeast counts, showed lower incidence of soft rots. 1-MCP treated celery received higher consumer acceptability scores. The effects were more marked on the samples obtained from the apical region of the petioles. Overall, results reassess the role of ethylene on celery petiole metabolism and indicate that 1-MCP treatments may be useful to supplement the benefits of refrigeration and extend the shelf life of fresh cut self-blanching celery.

Injury Criteria Associated with Soybean Exposure to Dicamba

AbstractResearch conducted in the field identified 14 injury criteria associated with dicamba (Clarity® diglycolamine salt) applied at 0.6 to 280 g ae ha–1(1/1,000 to 1/2 of 560 g ha–1use rate) to indeterminate soybean at V3/V4 or R1/R2. For each criterion, injury was rated using a scale of 0=no injury, 1=slight, 2=slight to moderate, 3=moderate, 4=moderate to severe, and 5=severe. Greatest crop injury 15 d after treatment (DAT) was observed for dicamba rates of 0.6 to 4.4 g ha–1for upper canopy pale leaf margins (3.8 to 4.2) at V3/V4 and for terminal leaf cupping (4.1 to 5.0) at R1/R2, and for rates of 0.6 to 8.8 g ha–1for upper canopy leaf cupping (3.8 to 4.8) and upper canopy leaf surface crinkling (3.4 to 4.4) at V3/V4. Injury 15 DAT was equivalent to the nontreated control for dicamba rates as high as 4.4 g ha–1for lower stem base swelling at V3/V4 and for upper canopy leaf rollover/inversion and terminal leaf necrosis at R1/R2; for rates as high as 8.8 g ha–1for leaf petiole base swelling and stem epinasty at R1/R2, and lower stem base lesions/cracking (V3/V4 and R1/R2 average); and for rates as high as 17.5 g ha–1for lower leaf soil contact at V3/V4 and leaf petiole droop at R1/R2. The response to increasing dicamba rate observed for the injury criteria was in contrast to the steady increase in visual injury and plant height reduction rated as 0 to 100%. The moderate to severe upper canopy leaf cupping, pale leaf margins, and leaf surface crinkling, and terminal leaf cupping 15 DAT with dicamba at 0.6 to 4.4 g ha–1corresponded to soybean yield loss of 1% to 9% for application at V3/V4 and 2% to 17% at R1/R2.

Foliar secretory structures in Melia azedarach (Meliaceae), a widely cultivated and often invasive tree

ABSTRACTMelia azedarach (chinaberry; syringa), a tree with bipinnately compound leaves, is one of the most widely cultivated of all tropical trees, but has become naturalised in several parts of the world. New observations are presented on the morphology and anatomy of extrafloral nectaries (EFNs). These should serve as baseline information in ecological studies on the invasiveness of the species, as well as its potential biocontrol. We report, for the first time, extrafloral nectaries (EFNs) on the leaflet lamina, as well as capitate glands on very young leaflets. A sugar analysis of the exudate of the former confirmed it to be nectar. In addition, known EFNs occurring in paired recesses at the petiole base were studied anatomically and developmentally. These so-called paired glands were found to be groups of individual and separate EFNs, for which the new term ‘compound EFN’ is suggested. Each EFN making up a compound EFN is similar in structure to the laminar EFNs except that they tend to protrude beyond the epidermal surface to a greater degree and to be composed of cells which differ slightly in shape. The secretory tissue of both petiolar and laminar EFNs originates from protoderm and ground tissues, albeit with slightly different initial cell divisions. Capitate glands were found on very young leaflets. Ants were frequent visitors to mainly the petiolar EFNs, less often the laminar ones. Members of the Meliaceae (including M. azedarach) are well known sources of limonoids, compounds with insect antifeedant properties. It is suggested that petiolar and laminar EFNs may attract different preferential nectar feeders, thus providing a first line of indirect defence, resulting in the removal or deterring of potential herbivores even before any damage is inflicted on the plant. Additionally, nectar from the EFNs may protect against co-evolved or other herbivores tolerant of limonoids.

Permineralized osmundaceous and gleicheniaceous ferns from the Jurassic of Inner Mongolia, NE China

Structurally preserved fossil ferns are extremely significant for exploring the origin and evolution of this plant clade; however, they are quite scarce and limited in the Mesozoic. Here, we report some well-preserved fern rhizomes and rachides with anatomical details from the Upper Jurassic Manketouebo Formation in Inner Mongolia, NE China. Two taxa, including Ashicaulis liaoningensis (Zhang et Zheng) Tidwell referred to Osmundaceae and Gleicheniorachis sinensis sp. nov. referred to Gleicheniaceae, are recognized. Anatomically, Ashicaulis liaoningensis consists of a heterogeneous pith, an ectophloic dictyoxylic siphonostele, a two-layered cortex, C-shaped leaf traces, and a mantle of petiole bases. The petiole base is characterized by a heterogeneous sclerotic ring with an abaxial thick-walled fiber arc. Gleicheniorachis sinensis sp. nov. consists of a C-shaped vascular bundle with two incurved adaxial hooks, a distinct sclerenchyma sheath, an endodermis, and a heterogeneous cortex. In particular, the finding of Gleicheniorachis sinensis sp. nov. represents the first report of unequivocal Jurassic record of Gleicheniaceae in northern China, as well as the first record of a Jurassic permineralized gleicheniaceous fern in the Northern Hemisphere. This study provides new data and evidence for exploring the anatomical diversity and evolution of Mesozoic ferns, and contributes to further understanding the floral composition of Late Jurassic flora in Northeast China.

Do we have infraspecific taxa of Salvia multicaulis Vahl. (Lamiaceae) in Iran?

<p><em>Salvia multicaulis</em> is a widespread species of Lamiaceae family in Iran. There are many discussions about its infraspecific variations. Although some varieties were definite for this species in various parts of the world, no infraspecific taxon was reported in Iran and all samples of this species were named as S. multicaulis. In this study, morphological characteristics of S. multicaulis populations, naturally growing in Iran, was examined. Twenty-two traits were examined in 94 individuals of this species to<br />identify their phenotypic difference. Most of the investigated features were showing a high degree of variability, but it was highly pronounced for some characteristics such as basal leaf shape, basal leaf width, basal leaf length/ width ratio and basal petiole length. Significant positive/negative correlations were observed between some morphological variables. Furthermore, significant negative correlations were found between the eastern distribution of populations with basal leaf petiole length and basal leaf length/ width ratio. Based on the UPGMA cluster analysis, populations were divided into two main branches. The first branch contained four populations, while the second branch was bigger and clustered in two sub-branches. In one of them,<br />three populations and in another one the rest populations arranged in two groups. CA joined plot confirmed that each of studied populations or group of populations had distinct morphological trait(s), which were useful in identification of them. Our findings supported population no. 13 had unique morphological traits such as the largest bracts and basal leaf petiole, highest flower number of each inflorescence cycle, widest and largest calyx. The conservation of the highly diverse populations of<br />Iranian S. multicaulis is recommended.</p>

First Report of Chrysanthemum Stem Blight and Dieback Caused by Tomato spotted wilt virus in China

Cultivated chrysanthemum (Chrysanthemum morifolium) is a popular flower species from China, where it is widely planted for use as tea and in medicines, as well as for ornamental purposes. In July 2016, a serious stem necrotic disease was observed on chrysanthemum in a commercial greenhouse in Beijing, China. Most chrysanthemum varieties were infected, with a total disease incidence above 50%, rising to over 90% in some sensitive cultivars. Infected chrysanthemum plants exhibited two main symptoms: (i) irregular chlorotic spots on the upper leaves with shortened internodes (cultivar Silvia), or (ii) discontiguous black streaks on stems near the base of the upper petioles, followed by eventual dieback (cultivars Dante, Radost, Stellini, and Olive). These symptoms are very similar to those of chrysanthemum infected with the tospoviruses Tomato spotted wilt virus (TSWV) or Chrysanthemum stem necrotic virus (CSNV). To identify the pathogen, infected chrysanthemum leaves were analyzed using reverse-transcription polymerase chain reaction (RT-PCR) with tospovirus universal primers (Hassani-Mehraban et al. 2016). After extracting the total RNA with a Plant RNA kit (Tiangen, Beijing, China), RT-PCR was performed using an RT-PCR kit (Vazyme, Nanjing, China), with infected chrysanthemum showing black streaks on stems as positive controls and virus-free plantlets as negative controls. RT-PCR products were bidirectionally sequenced by Sangon Biotech (Shanghai, China) and aligned in DNAstar. Three clones of 10 infected leaf samples (two of each cultivar) were collected from different sections of the greenhouse and sequenced, revealing high sequence similarity with fewer than 2-bp difference between them. The most conserved sequence, isolated from sample BLZ01, was deposited in GenBank under accession number MF196915. This sequence was 99% identical to TSWV S RNA segments in GenBank and distinctly different from CSNV RNAs, indicating that the devastating disease was caused by TSWV, not CSNV. This diagnosis was further confirmed using commercial ELISA kits (Luyuan Bode Biological, Beijing, China), which revealed TSWV but not CSNV in all symptomatic tissue. Additional RT-PCRs were performed using TSWV-specific (Chung et al. 2006; Qiu et al. 1998) and CSNV-specific (Takeshita et al. 2011) primers complementing the RNA-dependence RNA polymerase gene (L RNA), Gn/Gc gene (M RNA), and nucleocapsid protein gene (NP, S RNA), respectively, and the results confirmed those of the ELISA. Finally, the virus isolated from BLZ01 was mechanically transmitted from infected cultivar Olive collected from the original greenhouse to 1-month-old virus-free chrysanthemum seedlings using chilled 0.01 M phosphate buffer (pH 7.2) containing 0.1% sodium sulfite. After 2 weeks, most inoculated plants (13 of 18) exhibited localized necrotic spots and black streaks on their stems. RT-PCR and sequencing revealed that the partial sequence of the TSWV NP gene from the inoculated chrysanthemum was identical to the virus from the greenhouse materials. TSWV has spread and is causing epidemics on chrysanthemum in many countries. To our knowledge, this is the first report of TSWV detected on chrysanthemum in China, and this article will act as a warning to prevent the spread of TSWV in Beijing.

A New Species and Two First Records of Eriophyoid Mites (Trombidiformis: Eriophyoidea: Eriophyidae), From Egypt

A new vagrant eriophyoid mite species, Aculus polygonumnis sp. nov. collected from the weed Polygonum salicifolium Brouss. Ex Willd (Polygonaceae) was described and illustrated from Egypt. Redescription of two first record species, Aceria salicina (Nalepa, 1911), rec. n. collected from Salix babylonica L. and S. mucronata Thunb (Salicaceae), causing leaf rolling and buds, petiole bases, collected on malformed catkins; Anthocoptes salicis Nalepa, 1894, rec. n. collected from S. babylonica and S. mucronata (Salicaceae), vagrant on leaves. The genus Anthocoptes is recorded for the first time for the Egyptian fauna.

First Report of Phomopsis longicolla Causing Stem Necrosis on Soybean in Arkansas

Soybean plants (Glycine max (L.) Merr.) with stem necrosis symptoms were observed in several fields across southeast Arkansas, USA in 2016. Symptoms included reddish-brown elliptical lesions that progressed to slightly sunken cankers of varied lengths on stems with pycnidia sometimes observed in the area of necrotic tissue (Mathew et al. 2015; Vidic et al. 2013). Cankers girdling the stems 5-8 cm above the soil line were often found. Severely impacted plants were aggregated in approximately 3-10 m patches with a disease incidence >95% and <10% incidence more widespread in fields. In severely affected areas, symptoms advanced up the plant with necrosis occurring at petiole bases resulting in leaf and petiole pruning and pod abortions. Approximately 50 symptomatic plants were sampled from 5 fields in Desha (33.797790°, -91.278337°; 33.809550°, -91.278975°; and 33.946060°, -91.412891°), Lincoln (33.950424°, -91.902375°), and Jefferson (34.193164°, -91.902375°) counties. Forty fungal isolations from 3 cm piec...

First Report of Pectobacterium aroidearum Causing Soft Rot of Chinese Cabbage in China

HomePlant DiseaseVol. 102, No. 3First Report of Pectobacterium aroidearum Causing Soft Rot of Chinese Cabbage in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Pectobacterium aroidearum Causing Soft Rot of Chinese Cabbage in ChinaH. Xie, X. Y. Li, Y. L. Ma, and Y. TianH. Xie†Corresponding author: H. Xie; E-mail: E-mail Address: xiehua@baafs.net.cnSearch for more papers by this author, X. Y. LiSearch for more papers by this author, Y. L. MaSearch for more papers by this author, and Y. TianSearch for more papers by this authorAffiliationsAuthors and Affiliations H. Xie † X. Y. Li Y. L. Ma Y. Tian , Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, and Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing 100097, P. R. China. Published Online:19 Jan 2018https://doi.org/10.1094/PDIS-07-17-1059-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In June to October 2015, we surveyed Chinese cabbage (Brassica rapa subsp. pekinensis) exhibiting soft rot symptoms in a commercial field in Beijing, China. The lesions initiated at the petiole base, expanded, and rapidly covered the entire plant. Analysis of 30 isolates from infected plants revealed that one of them, KC20, was an isolate of Pectobacterium aroidearum, whereas the other 29 isolates were the common Chinese cabbage pathogen P. carotovorum. Bacterial strain KC20 was tested for pathogenicity by dropping a bacterial suspension (10 μl/inoculation site, 2 × 108 CFU/ml) onto sterilized Chinese cabbage petiole surfaces with sterile distilled water as a control. Water-soaked lesions appeared on inoculated petioles in 24 h after incubation in a growth chamber at 28°C, and strains were reisolated successfully from symptomatic Chinese cabbages to complete Koch’s postulates. In a PCR assay, strain KC20 produced a 434-bp product with pel gene-specific primers Y1/Y2 for Pectobacterium spp. (Darrasse et al. 1994). Analysis of 16S-23S intergenic transcribed spacer PCR (ITS-PCR) amplified by universal primers G1/L1 (Toth et al. 2001) and restriction fragment length polymorphisms generated by digestion with restriction enzymes Rsa I and Cfo I further demonstrated that KC20 isolate differed from P. carotovorum. BLASTn analysis of KC20 16S rDNA (GenBank accession no. MF155025) showed 99% nucleotide identity to that of P. aroidearum strain SCRI 109 (JN600323). Maximum likelihood phylogenetic trees based on 16S rDNA, pmrA sequences (KY021016)(Kettani-Halabi et al. 2013), and multilocus sequence analysis (Nabhan et al. 2012) of housekeeping genes (acnA, icd, gapA, mdh, mtlD, pgi, proA, and rpoS) (MF443741 to MF443748), all clustered KC20 into a clade containing other confirmed strains of P. aroidearum. Physiological tests, including 19 traditional physiological and biochemical tests and 94 phenotypes screened using the Biolog GN2 microplate system (Biolog, Haywood, CA), further confirmed our finding that the KC20 isolate was P. aroidearum (Nabhan et al. 2013). P. aroidearum exhibited a preference for monocotyledonous plants (Nabhan et al. 2013). This is the first report on occurrence of P. aroidearum in Chinese cabbage, which expanded the known host range for it, and also the first official report of the presence of P. aroidearum in Chinese territory.

Accessible Morphological and Genetic Markers for Identification of Taioba and Taro, Two Forgotten Human Foods

Some tropical species—such as the domesticated Xanthosoma sagittifolium (L.) Schott (Taioba) and Colocasia esculenta (L.) Schott (Taro)—have similar phenotypic characteristics, especially in the shape and color of the leaves and petioles which generate uncertainty in their identification for use in human food. This study aimed to analyze the morphological and molecular characteristics of X. sagittifolium and C. esculenta that may help in the popular and scientific identification of these species. The principal morphological characteristics of X. sagittifolium were as follows: leaves with subcoriaceous textures, basal insertion of the petiole, green pseudo-stem in the basal portion with exudate being white and the presence of two collector veins. Distinctive morphological characteristics of C. esculenta were as follows: leaves with velvety textures, peltate insertion of the petiole, pink pseudo-stem in the basal portion with pink exudate and presence of one collector vein. The morphological characteristics that can be used to distinguish Taioba from Taro are the basal petiole insertion of the first, against the petiole insertion near the center of the blade of the latter. Molecular analyses using eight Inter-Simple Sequence Repeat (ISSR) molecular markers simultaneously showed distinctive fingerprints for each of the species. These results contribute to the proper identification of the species used as a food source.