Cercospora Cruenta Research Articles

Status of Common Bean (Phaseolus vulgaris L.) Diseases in Metekel Zone, North West Ethiopia

Common bean has versatile benefits such as nutritional, environmental and economic benefits for the producers and consumers. However, its production has been affected and threatened by a number of biotic factors. Survey was conducted in 2018/19 cropping season within three woredas of Metekel Zone, Benshangul-Gumz region, Ethiopia, with the objective of identifying and prioritizing haricot bean diseases.The result revealed that haricot bean production in the Zone is affected by eleven diseases which are caused by fungi, bacteria and virus. Based on the disease severity, incidence and prevalence scores, the diseases are categorized in to Major, intermediate and Minor disease. Angular Leaf Spot (Pseudocercospora griseola), Anthracnose (Colletotrichum lindemuthianum), Floury leaf spot (Mycovellosiella phaseoli), and Cercospora leaf spot (Cercospora cruenta are grouped in to major diseases. Rust (i), Web blight Rhizoctonia solani Kuhn (teleomorph Thanatephorus cucumeris (Frank) Donk), Ascochyta blight (Phomaexigua var. exigua/Ascochyta phaseolorum acc) and Bean common mosaic virus (potyvirus) are categorized as Intermediate and the remaining three diseases: Halo blight (Pseudomonas syringaepv. phaseolicola), Common Bacterial Blight (Xanthomonas axonopodis pv phaseoli) and Downy Mildew (Phytophthora phaseoli Thaxt) are grouped under minor diseases. The survey revealed, the common bean production and disease management practices and variety development efforts for the Zone, onwards, should focus on those major disease (such as Angular Leaf Spot, Anthracnose, Floury leaf spot, and Frog Eye leaf spot) in order to sustain production and productivity of common bean cultivars.

Biosynthesis of Abscisic Acid by the Direct PathwayviaIonylideneethane in a Fungus,Cercospora cruenta

We examined the biosynthetic pathway of abscisic acid (ABA) after isopentenyl diphosphate in a fungus, Cercospora cruenta. All oxygen atoms at C-1, -1, -1', and -4' of ABA produced by this fungus were labeled with (18)O from (18)O(2). The fungus did not produce the 9Z-carotenoid possessing gamma-ring that is likely a precursor for the carotenoid pathway, but produced new sesquiterpenoids, 2E,4E-gamma-ionylideneethane and 2Z,4E-gamma-ionylideneethane, along with 2E,4E,6E-allofarnesene. The fungus converted these sesquiterpenoids labeled with (13)C to ABA, and the incorporation ratio of 2Z,4E-gamma-ionylideneethane was higher than that of 2E,4E-gamma-ionylideneethane. From these results, we concluded that C. cruenta biosynthesized ABA by the direct pathway via oxidation of ionylideneethane with molecular oxygen following cyclization of allofarnesene. This direct pathway via ionylideneethane in the fungus is consistent with that in Botrytis cinerea, except for the positions of double bonds in the rings of biosynthetic intermediates, suggesting that the pathway is common among ABA-producing fungi.

Herança da resistência genética do caupi à cercosporiose

A cercosporiose do caupi (Vigna unguiculata), causada por Cercospora cruenta, constitui importante problema sanitário para a cultura e o seu controle é mais eficiente com o uso da resistência genética. Portanto, o conhecimento do tipo de herança é essencial para o melhoramento visando resistência a esta doença. O trabalho foi realizado em condições de campo, utilizando-se a linhagem resistente L101000-1 e a cultivar suscetível IPA 206. A hibridação foi efetuada entre plantas dos dois genótipos e através da técnica de emasculação de flores, foram obtidas as populações F1, F2 e F3. As gerações paternais e segregantes foram plantadas e inoculadas três vezes, as inoculações foram realizadas aos 20, 27 e 34 dias do plantio. A suspensão contendo 4x10³ con/ml do fungo foi preparada a partir da coleta de conídios em lesões de folhas infetadas. A avaliação dos sintomas, em plantas individuais, foi realizado aos 75 dias após o plantio, com base na reação de resistência ou suscetibilidade. As plantas da linhagem L101000-1 e a população F1 comportaram-se como resistentes, enquanto que as da cultivar IPA 206 apresentaram sintomas típicos da cercosporiose. Na geração F2, das 132 plantas observadas, 105 foram resistentes e 27 suscetíveis e na geração F3, das 90 plantas avaliadas, 70 foram resistentes e 20 suscetíveis. Estes resultados foram analisados pelo teste do Qui-quadrado e sugerem que a herança da resistência a C. cruenta, na cultivar L101000-1, é do tipo monogênica e dominante.

Identification of 2,3-dihydro-gamma-ionylideneethanol in Cercospora cruenta.

During our scrutiny of GC-EI-MS date for C15 alcohols as putative intermediates on the ABA biosynthetic pathway in Cercospora cruenta, a trace amount of 5-[2',2'-dimethyl-6'-methylene-1'-cyclohexyl]-3-methyl-4-penten-1-ol (2,3-dihydro-gamma-ionylideneethanol) was identified. Feeding experiments indicated that this compound was not an intermediate to ABA, but a catabolite that originated from gamma-ionylideneacetaldehyde. The stereochemistry of 2,3-dihydro-gamma-ionylideneethanol was deduced to be (3R,1'S) from a comparison with an authentic specimen prepared via baker's yeast asymmetric reduction.

Incorporation of Farnesyl Pyrophosphate Derivertives into Abscisic Acid and Its Biosynthetic Intermediates in Cevcospova cruenta.

To investigate the transformation from (2E,6E)-farnesyl pyrophosphate to (2Z,4E)-γ-ionylideneethanol in the abscisic acid-producing fungi, Cercospora cruenta, plausible [2-14C]-C15 intermediates were prepared and fed. Substrates such as (2E,6E)-farnesyl pyrophosphate, (2Z,4E)-γ-ionylideneethanol and its pyrophosphate were incorporated into ABA and its known biosynthetic precursors. It is suggested that (2E,6E>farnesyl pyrophosphate is converted to (2Z,4E)-γ-ionylideneethanol in four consecutive steps: dehydrogenation, isomerization, cyclization and hydrolysis.

Conformational Analysis of Abscisic Acid Analogs Produced by Cercospora cruenta.

The conformation of hydroxy-γ-ionylideneacetic acids produced by Cercospora cruenta was examined by 'H-NMR analysis. (1)H-(1)H COSY and NOE data indicated that (2Z,4E,1'R,4'#)-4'-hydroxy-(γ)- ionylideneacetic acid has a cyclohexane ring of chair form furnishing a hydroxyl group and a 2,4-pentadienoic acid moiety, each with equatorial orientation, while (2Z,4E,1'S,3'S)-3'-hydroxy-γ-ionylideneacetic acid has a flexible twisted-boat form of cyclohexane ring. It is suggested that the structure of another (2Z,4E,1'S,4'R)-isomer of 4'-hydroxy-γ-ionylideneacetic acid with an equatorial hydrogen at the l'-position is the key for further oxygenation to abscisic acid.

Chiral synthesis and stomatal closure activities of γ- pseudo- and dihydro-abscisic acids

Analogues of abscisic acid (ABA) were prepared from chiral cyclohexanone building blocks. Synthetic (1′ R, 3′ S)-1′, 3′- γ-dihydroxy- γ-ionylideneacetic acids and ( R)-1′-hydroxy-3′-oxo- γ-ionylideneacetic acid (tentatively named γ- pseudo-ABA) provided authentic data for new metabolities isolated from Cercospora cruenta. Both enantiomers of 2′, 3′-dihydroABA were also prepared. Only the (1′ S, 2′ S)-isomer of 2′, 3′-dihydroABA induced substantial closure of stomata on the epidermal strips of Commelina communis.

Biosynthesis of Abscisic Acid in the Fungus <italic>Cercospora cruenta</italic>: Stimulation of Biosynthesis by Water Stress and Isolation of a Transgenic Mutant with Reduced Biosynthetic Capacity

Biosynthesis of Abscisic Acid in the Fungus <italic>Cercospora cruenta</italic>: Stimulation of Biosynthesis by Water Stress and Isolation of a Transgenic Mutant with Reduced Biosynthetic Capacity

Isolation and metabolism of 3′-hydroxy-γ-ionylideneacetic acids in Cercospora cruenta

Four isomers of 3′-hydroxy-γ-ionylideneacetic acid were isolated from Cercospora cruenta cultures. The ratio of isomers was found to be 44:24:21:11 for (2 Z,4 E)-(1′ S,3′ S)-, (2 Z,4 E)-(1′ S,3′ R)-, (2 E,4 E)-(1′ S,3′ S)- and (2 E,4 E)-(1′ S,3′ R)-3′-hydroxy-γ-acid, respectively. Feeding experiments with [ 14C] labelled (2 Z,4 E)-(1′ S,3′ S)-3′-hydroxy-γ-acid showed high incorporation into 1′,3′-dihydroxy-γ-acid and 1′-hydroxy-3′-oxo-γ-acid, but not into 4′-hydroxy-γ-acids. This result suggested that 3′-hydroxy-γ-acids were not involved in the ABA biosynthetic pathway. The biological activities of these new metabolites were compared with those of known ABA biosynthetic intermediates.

BETTERSNAP: A NEW, EDIBLE PODDED SOUTHERNPEA

Bettersnap southernpea (Vigna unguiculata) was developed as a replacement for the popular cultivar Snapea. The new cultivar is well adapted for production throughout the southern United States where it can be expected to produce excellent yields of edible pods or snaps. Bettersnap is resistant to root knot, a severe root disease incited by several species of the root-knot nematode (Meloidogyne spp.), and blackeye cowpea mosaic virus, the major pathogen of southernpea in the United States. Observations of natural epiphytotics indicate that the cultivar is also resistant to scab (Cladosporium vignae) and cercospora leaf spot (Cercospora cruenta). The new cultivar has the same maturity and high yield potential as Snapea. Bettersnap is recommended for use as a home garden cultivar for spring, mid-season, and fall plantings. It is particularly recommended for trial as a commercial processing cultivar for the production of the immature green pods used for the ``snap” component of the popular mixed packs of fresh peas and green snaps.

Syntheses of chiral 4'-hydroxy and 1',4'-dihydroxy-.GAMMA.-ionylideneacetic acids, fungal biosynthetic intermediates of abscisic acid.

Both chiral 4'-hydroxy and 1', 4'-dihydroxy-γ-ionylideneacetic acids (3, 4 and 5), biosynthetic intermediates of abscisic acid produced by Cercospora cruenta, were synthesized from a chiral starting material, (R)- or (S)-4-hydroxy-2, 2-dimethyl-1-cyclohexanone (7). [2.3]-Sigmatropic rearrangement of (S)-1-chloromethyl-3, 3-dimethyl-5-tetrahydropyranyl(THP)oxy-1-cyclohexene (8), followed by the Reformatsky reaction with 4-bromo-3-methyl-2-butenoate (10) gave (l'R, 4S)-4. The diastereomeric isomer, (l'R, 4'R)-3, was synthesized in the same manner. The reaction of (S)-2, 2-dimethyl-5-methylene-4-THPoxy-1-cyclohexanone (14) with a Grignard reagent prepared from (Z)-3-methyl-2-penten-4-ynyI THP ether (15) and subsequent conversion of the side chain gave (1'S, 4'S)-5. These synthetic compounds confirmed the stereochemistry of natural 3, 4 and 5.

Metabolism of (2Z,4E)-.GAMMA.-ionylideneethanol and (2Z,4E)-.GAMMA.-ionylideneacetic acid in Cercospora cruenta.

[2–14C]-(2Z,4E)-γ-Ionylideneethanol and [2–14C]-(2Z,4E)-γ-ionylideneacetic acid were converted by Cercospora cruenta to [2–14C]-(2Z,4E)-1′,4′-dihydroxy-γ-ionylideneacetic acid and [2-14C]-(2Z,4E)-4′-hydroxy-γ-ionylideneacetic acid, which are intermediates of ABA biosynthesis in C. cruenta.

Conversion of (2 Z,4 E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid to xanthoxin acid by Cercospora cruenta, a fungus producing (+)-abscisic acid

(±)-(2 Z,4 E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid was metabolized by Cercospora cruenta, which has the ability to produce (+)-abscisic acid (ABA), to give (±)-(2 Z,4 E)-xanthoxin acid, (±)-(2 Z,4 E)-5′-hydroxy-1′,2′-epoxy-1′,2′-dihydro-β-ionylideneacetic acid, (±)-1′,2′-epoxy-1′,2′-dihydro-β-ionone and trace amounts of ABA.

‘Carolina Cream’ Southernpea

Abstract ‘Carolina Cream’ is a new southernpea [Vigna unguiculata (L.) Walp.] cultivar that was approved for release in July 1982 by the Agricultural Research Service of the USDA. It is well-adapted for production throughout the southeastern United States, where it can be expected to produce excellent yields of high quality, cream-type peas. Major attributes of the new cultivar are its excellent culinary quality and its resistances to the cowpea curculio (Chalcodermus aeneus Boehman), the major insect pest of the southernpea, and Cercospora leaf spot [Cercospora cruenta Sacc. (= Mycosphaerella cruenta Latham)], a major foliage disease of the crop. Cercospora leaf spot on southernpea also can be incited by Cercospora canescens Ell. & Martin.

‘Colossus 80’ Southernpea1

Abstract ‘Colossus 80’ southernpea [Vigna unguiculata (L.) Walp] has been released by the U.S. Department of Agriculture and Clemson University as a replacement for ‘Colossus’, a widely adapted and popular home garden and fresh-market cultivar that was released by Clemson University in 1972 (8). ‘Colossus 80’ is highly resistant to Cercospora leaf spot (CLS), a disease incited by Cercospora cruenta Sacc. (= Mycosphaerella cruenta Latham)5. CLS is one of the most serious foliage diseases of southernpeas in the southeastern United States and infection of susceptible cultivars results in premature defoliation and reduced yields. The original ‘Colossus’ is highly susceptible to this disease. Fery et al. (7) reported reductions of 36, 25, 10, and 3% in total seed yield, pod number, seed number per pod, and average weight per 100 seed, respectively, in a naturally infected ‘Colossus’ planting.

Influence of Chlorothalonil, Nitrogen, and Tillage Practices on Cercospora Leafspots and Rust in Southernpea (Vigna unguiculata (L.) Walp)1

Abstract Nitrogen did not influence the severity of leafspots (Cercospora cruenta and C. canescens) or rust (Uromyces phaseoli var. vigna), but these foliage disease were more severe on southernpea plants grown in disk-harrowed treatments than in treatments deep-turned with a moldboard plow. Three applications of chlorothalonil reduced the severity of Cercospora leafspots and rust, but did not effectively control the diseases in all tests. Foliage diseases were less severe on ‘White Acre’ than on ‘Purpose Hull Pinkeye’ southernpea. ‘White Acre’ produced the most foliage in disk-harrowed treatments, and ‘Purple Hull Pinkeye’ was superior in deepturned treatments.

An Assessment of Two Genes for Cercospora Leaf Spot Resistance in the Southernpea (Vigna unguiculata (L.) Walp.)1

Abstract The gene Cls1 and the recessive gene cls2 each conditions a high level of resistance to a leaf spot incited by Cercospora cruenta Sacc. Two Cercospora leaf spot (CLS) resistant breeding lines, CR 17-1-34 (homozygous for Cls1) and Ala. 963.8 (homozygous for cls2), were crossed with each other and with each of 3 susceptible cultivars. The F1 and F2 progenies of these crosses, the backcrosses of the CR 17-1-34 × Ala. 963.8 cross, and the parental lines were grown in a field experiment in which a natural CLS epiphytotic was allowed to develop. Cls1 was completely dominant in all crosses; no evidence was found that either modifying factors or environment had any significant impact on its expression. The cls2 allele was found not to be a complete recessive under weak epiphytotic conditions, but an incomplete dominant that was highly influenced by the environment when in the heterozygous condition. Cls1 and cls2 were neither allelic nor linked.

Factors affecting Spore Germination in Cowpea Isolate of Cercospora cruenta Sacc.

Factors affecting Spore Germination in Cowpea Isolate of Cercospora cruenta Sacc.

The Inheritance of Cercospora Leaf Spot Resistance in the Southernpea (Vigna unguiculata (L.) Walp.)1

Abstract Two southernpea breeding lines, CR 17-1-34 and Ala. 963.8, highly resistant to a leaf spot incited by Cercospora cruenta Sacc. were crossed with susceptible cultivars. The F1 and F2 progenies of these crosses, the F1 of the backcrosses, and the parental lines were grown in field experiments in which natural Cercospora leaf spot epiphytotics were allowed to develop. The resistances in the two breeding lines were found to be conditioned by different genetic factors. Resistance in CR 17-1-34 was controlled by a single dominant gene and that in Ala. 963.8 by a single recessive gene. We propose that the dominant and recessive genes to be designated Cls1 and cls2, respectively.

CR 17-1-34, Cercospora Leaf Spot Resistant Southernpea Germplasm1

Abstract Cercospora leaf spot, a disease incited by Cercospora cruenta Sacc., is one of the major foliage diseases of southernpeas (Vigna unguiculata (L.) Walp.) in several important U.S. production areas3. The disease is frequently a problem on fall crops where severe losses are occasionally observed. Cercospora leaf spot spreads very rapidly on susceptible cultivars, resulting in premature defoliation and reduced yields. Schneider4 reported that C. cruenta caused yield reductions of 42% in Nigeria. Accessions of V. unguiculata resistant to C. cruenta have been reported by Verma and Patel (3) and Vakin4. Schneider (3) used resistant cultivars in his work. The lack of information about the inheritance of resistance and the agronomic or exotic nature of many of these lines limit their value as sources of Cercospora leaf spot resistances in horticultural breeding programs. The breeding line CR 17-1-34 has been released for use as a resistant parent in such programs. It is a horticultural type that carries one of the genes reported by Fery et al. (2) to condition a high level of resistance to Cercospora leaf spot.