Cryptic diversity, multilocus phylogeny, and pathogenicity of cercosporoid fungi associated with common bean and cowpea

Yardlong bean (Vigna unguiculata ssp. unguiculata cv-gr. sesquipedalis) is a type of cowpea (Vigna unguiculata). It is an important vegetable legume crop of Asia. One of the problems in yardlong bean production is the devastation of Cercospora leaf spot (CLS) disease caused by the fungi Cercospora canescens and Pseudocercospora cruenta which can cause yield loss from 35 to 40 %. Breeding for resistance cultivar(s) takes a long time and yet evaluating for the resistance is difficult and laborious. The objective of this research is to locate major gene/quantitative trait locus (QTL) controlling CLS resistance in yardlong bean with the ultimate goal to identify SSR markers closely linked to the resistance gene for marker-assisted selection. An F2 population of 190 plants was developed from a cross between yardlong bean breeding line “CSR12906” (susceptible) and cowpea (Vigna unguiculata ssp. unguiculata) breeding line “IT90K-59-120” (resistant). The F2 plants and F2:3 families were evaluated for the CLS resistance caused by C. canescens and/or P. cruenta using a visual scoring method. Bulked segregant analysis (BSA) was conducted using simple sequence repeat (SSR) markers. Location of the QTL controlling the resistance was determined by inclusive composite interval mapping (ICIM). Disease evaluation revealed that the disease scores were continuously distributed, suggested that the resistance in IT90K-59-120 is a quantitative trait. BSA showed that SSR marker CEDG304 on linkage group 9 (LG9) of yardlong bean associated with the resistance. ICIM identified a major QTL, coined as qCLS9.1, for the resistance on LG9. qCLS9.1 accounted for 25.40–89.26 % of the disease score variation depending on environment and population. Linkage and genome comparison revealed that qCLS9.1 is likely the same as QTL ALS10.1 conferring resistance to angular leaf spot disease caused by P. cruenta in common bean (Phaseolus vulgaris).

Aim of the current study was to evaluate soya bean genotypes for yield and yield traits and cercospora (Cercosporasojina) leaf spot disease under field condition. Field experiment was conducted at Humera district during 2018 cropping season using 16soya bean genotypes. Treatments were evaluated with RCBD and replicated three times. Number of days from planting to days of flowering and days of maturity, number of pod per plant, pod shattering, seed yield and cercospora leaf spot disease were showed a significant (P<0.01) variation among genotypes. All varieties were moderately resistance to pod shattering except PN13-1 (3.1) was moderately susceptible and Parc-3, Parc-5 and PN13-10were resistance. Highest yields were recorded from genotypes PN13-2 at 20.32q/ha and PN13-9 at 19.77q/ha. On the other hand, the lowest yields were recorded from genotypes PN13-3 at 7.49q/ha and PN13-1 at 9.95q/ha. Genotypes PN13-2 and PN13-7 have been identified as displaying resistance to Cercospora leaf spot. Highest disease severity recorded in genotypes Awassa 04 and PN13-1. Further research is needed in future to cover a wide range of environments and genotypes to screen high yielder and cercospora leaf spot disease resistance.

Acceleration of histopathological and biochemical defense patterns in mung bean with biopriming of Amycolatopsis sp. SND-1 against Cercospora leaf spot disease

Six populations (Parent 1, Parent 2, F1, F2, BC1 and BC2) generated from each of four crosses involving four resistant and two susceptible varieties of cowpea (Vigna unguiculata L. Walp) were evaluated for resistance to Cercospora leaf spot (CLS) disease caused by Pseudocercospora cruenta under induced epiphytotic conditions, in four separate field experiments. Climatic conditions determined the onset of CLS disease in the susceptible cultivar and varied in the four experiments from 35 to 48 days after planting (DAP). Genetic analysis revealed that the mode of inheritance of resistance to P. cruenta can be oligogenic or polygenic depending upon the cross. This is the first report of polygenic inheritance of CLS resistance. Number of nodes infected fitted a simple additive dominance model with predominance of additive effects based on generation mean analysis. Oligogenic resistance was observed for the other three crosses, with the most plausible models being: a single gene model with incomplete dominance in CB27 × IT87D-939-1; a single gene model with complete dominance in CB27 × VRB-10; and a triger model in Los Banos Bush Sitao × IT86D-792, based on segregation analysis of symptomatic : non-symptomatic plants. The role of minor genes was also indicated in the above crosses. Suggested approaches to breeding for resistance to CLS are discussed.

Cryptic diversity, pathogenicity, and evolutionary species boundaries in Cercospora populations associated with Cercospora leaf spot of Beta vulgaris

The genus Cercospora includes many important plant pathogenic fungi associated with leaf spot diseases on a wide range of hosts. The mainland of Iran covers various climatic regions with a great biodiversity of vascular plants, and a correspondingly high diversity of cercosporoid fungi. However, most of the cercosporoid species found to date have been identified on the basis of morphological characteristics and there are no cultures that support these identifications. In this study the Consolidated Species Concept was applied to differentiate Cercospora species collected from Iran. A total of 161 Cercospora isolates recovered from 74 host species in northern Iran were studied by molecular phylogenetic analysis. Our results revealed a rich diversity of Cercospora species in northern Iran. Twenty species were identified based on sequence data of five genomic loci (ITS, TEF1-α, actin, calmodulin and histone H3), host, cultural and morphological data. Six novel species, viz. C. convolvulicola, C. conyzae-canadensis, C. cylindracea, C. iranica, C. pseudochenopodii and C. sorghicola, are introduced. The most common taxon was Cercospora cf. flagellaris, which remains an unresolved species complex with a wide host range. New hosts were recorded for previously known Cercospora species, including C. apii, C. armoraciae, C. beticola, C. cf. richardiicola, C. rumicis, Cercospora sp. G and C. zebrina.

Groundnut (Arachis hypogaea L.) is an important crop both in subsistence and commercial agriculture in arid and semi-arid regions of the world. Leaf spot diseases caused by fungus have been a major destructive disease of groundnut and could cause a yield loss of up to 50 % or more. A two-year experiment was conducted during the cropping seasons of 2002 and 2003 at the Faculty of Agriculture Research Farm, University of Maiduguri, Nigeria. The objective of the study was to determine the reaction of different groundnut varieties to cercospora leaf spot disease to create basis for selection for cercospora leaf spot disease tolerance. The experiment consisted of twenty-four groundnut varieties, laid out in a randomized complete block design (RCBD) with three replications. The analysis of variance (ANOVA) indicated highly significant difference among the groundnut varieties in all the characters studied. The results indicated that ICGV-SM-93531, ICGV-IS-96802, ICGV-IS-96827 and ICGV-IS-96808 had the lowest cercospora leaf spot incidence. The variety ICGV-IS-96808 that produced the highest kernel yield also had the lowest days to 50% flowering and incidentally is among varieties that recorded the lowest leaf spot incidence. The study found tremendous level of variability existing among the groundnut varieties that is essential in crop improvement. This study recommends that development or selection of tolerant varieties to leaf spot should be based on their level of incidence. This will be the only effective measure in decreasing production costs and protect the environment from pollution. Potential therefore exist for selection among the groundnut varieties evaluated for cercospora leaf spot disease tolerance. There is however, a need to undertake further studies in order to determine the type and the number of genes controlling cercospora leaf spot disease tolerance in groundnuts for enhanced breeding strategies.

Identify the sources of resistance to Cercospora leaf spot and Fusarium wilt diseases in Cotton under natural field conditions with artificial inoculation at Regional Agricultural Research Station, Warangal of the Telangana State in India. The experimental material consisted of Fifty two cotton germplasms and 13 Bt cotton hybrids with a check. They were tested against Cercospora leaf spot and Fusarium wilt diseases during Kharif 2016. Out of 52 cotton germplasms,14 entries viz.,HYPS-152,H-1250,SA-434,KH-2244N,KH-134,MRK-38,LH-2170,AKH-2822,LH-900,JK-2764,NH-615, GBHU-164,RAH-100 and HOC-5 were found resistant to Cercospora leaf spot and nine entries namely MCU-13, HYPS-152, H-1250, RAH-4, RCH-2, JK-2764, CCH1071, SCS-101, CCH-11 were found resistant to Fusarium wilt disease.Out of screened 13 Bt cotton hybrids, one entry Ankur-3224 was found resistant to Cercospora leaf spot disease and three entries namely First class, Ankur-3224 and RCH-812 were found moderately resistant to Fusarium wilt disease.

Niger (Guizotia abyssinica Cass.) is an important minor oil seed crop grown in dry areas grown mostly by tribal and interior places as life line of tribal segment. Tribal people mainly use its oil for cooking purpose, above than that there were also other uses. Hence, the niger crop should be protected from the infection. The crop is affected by number of fungal diseases. Therefore, a field experiment was formulated for three years with the four replications at the Niger Research Station (NRS) at Navsari Agricultural University (NAU), Vanarasi, Navsari (Gujarat) on the foliar diseases of GN-1 variety of niger crop. In this experiment, six different fungicides along with one control have been evaluated to control the Alternaria and Cercospora leaf spot diseases, out of which all the fungicidal treatments were significantly superior over the control. Here, foliar spray on the incidence of diseases was compared with the control (without any treatment). All the fungicidal treatments were significantly superior over the control to reduce Alternaria and Cercospora leaf spot diseases of Niger crop. Treatment of Carbendazim + Mancozeb (0.2 %) with two sprays first from the initiation of the disease and second after the interval of 15 days recorded the lowest incidence of Alternaria (14.56) and Cercospora (14.94) leaf spot diseases of niger and recorded the highest seed yield 337 seed yield kg/ha along with the net return with cost benefit ratio graph.

Naturally, under field conditions, plants are regularly experienced by a mixture of two or more stress factors. Drought is a major abiotic stress, and fungal pathogens characterize a main biotic stress challenge faced by plants and impact negatively on plant development and productivity. We propose that foliar application of nitric oxide (NO) donors can have positive effects on the induction of tolerance to biotic and abiotic stress on groundnut plants. This investigation was carried out to study the changes in growth, some biochemical aspects, and yield and quality of groundnut plants as well as induction of resistance to Cercospora leaf spot disease in response to nitric oxide (NO) donors, sodium nitroprusside (SNP), and arginine (Arg) (2.5, 5.0, and 7.5 mM) under two water irrigation levels 100% and 75% of water irrigation requirements (WIR), in two field experiments through two successive growing seasons of 2021 and 2022. Decreasing irrigation water significantly reduced shoot length, branches numberplant-1, shoot fresh and dry weight, photosynthetic pigments components, endogenous indole acetic acid (IAA) contents, and yield components. Furthermore, root fresh and dry weight, phenols, total soluble sugars (TSS), proline contents, and the accumulation of hydrogen peroxide (H2O2) and lipid peroxidation of groundnut leaves increased significantly. Contrarily, foliar application with Arg and SNP alleviated the negative influences of drought on growth and productivity of groundnut plants via enhancing photosynthetic pigments, IAA, phenolic compounds, TSS, and proline contents. Additionally, SNP and Arg significantly decreased oxidative damage through decreasing H2O2 and lipid peroxidation by the induction of antioxidant enzymes. Remarkably, the increase of drought level led to a reduction in Cercospora leaf spot (CLS) disease with the use of high concentrations of both Arg and SNP. Interestingly, in both stressed and unstressed plants, SNP treatment at 7.5 mM was the most effective in reducing the incidence and severity of disease, while Arg at 2.5 mM recorded the lowest reduction compared to other treatments. In conclusion, foliar treatment of either SNP or Arg is a profound effect on modulating the drought stress and induction of resistance to Cercospora leaf spot disease of groundnut plants throughout regulating physiological and biochemical processes associated with photosynthesis and oxidative responses.

Two members of the Araceae broadly cultivated as ornamentals, namely Epipremnum aureum (common name golden pothos or, in Brazil, jiboia) and Zantedeschia aethiopica (common name arum lily or, in Brazil, copo‐de‐leite), were observed bearing Cercospora leaf spots. The former is a very common garden plant, whereas the latter is an important crop for the flower industry. An examination of the fungus associated with the disease on each plant revealed a very similar morphology which suggested that those might be conspecific. A polyphasic taxonomic study, including phylogenetic analyses based on act, cal and his3 sequences, was conducted. Both isolates from the two aroids were found to belong to the Cercospora apii complex, but were genetically distinct. Cercospora sp. Q was identified as the etiological agent of the leaf spots on E. aureum, whereas the fungus on Z. aethiopica was found to belong to Cercospora sp. G. Inoculations confirmed the pathogenicity of both isolates to their original hosts, and cross‐pathogenicity assessments revealed that both isolates were capable of infecting both E. aureum and Z. aethiopica. The limited morphological and pathological distinction between the fungi on these two hosts reflects the continued difficulty in the taxonomic treatment and species delimitation for Cercospora sp. G, Cercospora sp. Q, as well as other provisional code‐based Cercospora spp., and other components of the broad C. apii s. lat. complex. The name Cercospora richardiicola (as C. richardiaecola) was mistakenly used for the fungus on Z. aethiopica in earlier publications and this has been corrected herein.

BIOSYNTHESIS of Zn nanoparticles(NPs) from 32 various plant samples were tested and subjected to 11 samples of ZnONPs from plant aqueous extracts, wherever, ZnNo3(1mmole) was used as precursor to synthesizing of ZnONPs. The UV-Vis spectral analysis of Morus nigra and Grevillea robusta plant leaves mix extracts (reaction mixture) were confirmed and showed performance of Zn NPs and exhibited as new sources for clean production and could be explored in various fields. During two tested seasons 2015/2016 and 2016/2017 and field conditions showed that, NPs of Ti followed by Zn caused to reducing of cercospora leaf spot (CLS) disease severity percentage of sugar beet plants and enhancement of TSS and sucrose contents, especially under high disease severity stress in season 2015/2016 compared to protected plants by eminent fungicide and control. NPs led to activation and recorded high enzymes activity values of enzymes of peroxidase up to 6 min and polyphenoloxidase up to 4 min estimation periods compared to control, so exhibited as mechanism in defense against CLS disease. Unseasonable weather conditions of temperature degrees, relative humidity percentage, wind velocity, pan evaporation and rain played an essential role in changement of CLS disease severity and susceptibility under field conditions during two tested seasons. The results recorded high percentages with first date of planting in September month in the first season of 2015/2016 with seven sugar beet genotypes than the second ones of October month and season of 2016/2017.

Association of cropping practices, cropping areas, and foliar diseases of common bean (Phaseolus vulgaris L.) in Ethiopia

Crapemyrtle ( Lagerstroemia sp.) is a top-selling deciduous flowering tree in the United States, and its salability is often compromised by cercospora ( Cercospora lythracearum Heald & F. A. Wolf) leaf spot. To compare cercospora leaf spot resistance, 32 crapemyrtle cultivars belonging to Lagerstroemia indica , Lagerstroemia fauriei , L. indica × L. fauriei, and L. indica × L. fauriei × Lagerstroemia limii and 12 cultivars or unnamed selections belonging to L. indica , L. indica × L. fauriei , L indica × L. fauriei × L. limii, L. limii , and Lagerstroemia subcostata were planted in field plots in 2004 and 2011, respectively. The experiment was a completely randomized block design with three and four replications in the 2004 and 2011 plantings, respectively. Plants were evaluated for cercospora leaf spot disease severity and defoliation using a scale of 0% to 100% foliage affected from August to October of 2015, 2016, and 2017. Area under the disease progress curve (AUDPC) was calculated for the evaluation period of each year. L. fauriei cultivars Fantasy, Kiowa, Townhouse, and Woodlander’s Chocolate Soldier and L. indica × L. fauriei Apalachee from the 2004 planting, and the L. subcostata and L. limii selections from the 2011 planting had lowest cercospora leaf spot disease severity ratings, AUDPC, and defoliation. L. indica × L. fauriei cultivars Choctaw, Miami, Natchez, Osage, Sarah’s Favorite, Tonto, Tuscarora, and Tuskegee, and L. indica × L. fauriei × L. limii Arapaho were moderately resistant to cercospora leaf spot, whereas cultivars belonging to L. indica and L. indica × L. fauriei × L. limii Cheyenne were highly susceptible to cercospora leaf spot. Results from this research may aid breeders, nursery producers, and landscapers in selecting crapemyrtle species and cultivars with cercospora leaf spot resistance.

Studies on the inheritance pattern of bacterial leaf spot (BLS), yellow mosaic (YM) and Cercospora leaf spot (CLS) reactions in crosses of BLS and YM resistant/tolerant but CLS susceptible × CLS resistant but BLS and YM susceptible parents indicated that resistances to BLS and CLS were governed by single dominant genes, whereas YM tolerance was a monogenic recessive character. The studies also indicated that these three genes were inherited independently. The simple inheritance pattern and independent assortment of the genes governing resistance/tolerance to these diseases suggest that the usual breeding methods will be adequate to develop multi-disease resistant mungbean cultivars.