QTL mapping of partial resistance to basal stem rot in sunflower using recombinant inbred lines

Basal stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in sunflower (Helianthus annuus L.). Quantitative trait loci (QTLs) implicated in partial resistance to basal stem rot disease was identified using the 116 recombinant inbred lines (RILs) from the cross between the sunflower parental lines PAC2 and RHA266. RILs and their parents were arranged in a completely randomized design with six replications and inoculated with a moderately aggressive isolate (SSU107) of S. sclerotiorum under controlled conditions. QTLs were mapped using a recently developed high-density single sequence repeat/ amplified fragment length polymorphism (SSR/AFLP) sunflower linkage map. Analysis of variance showed highly significant differences among the sunflower genotypes for susceptibility to basal stem rot. The frequency distribution of genotypes for susceptibility to disease showed continuous patterns, suggesting that resistance is controlled by a polygenic system. Transgressive segregation for resistance occurred in this cross. Composite interval mapping analysis revealed 7 QTLs for percentage necrotic area, localized on 7 linkage groups. The effects of QTLs were small to moderate indicating a polygenic control of the studied character. However, like any other quantitative trait, it is necessary to confirm the position of the QTLs and carry out fine-scale mapping before marker assisted selection (MAS). LG8 and LG16 are good candidates for further analysis to develop molecular markers for resistance to Sclerotinia disease

Apple crown and collar canker and necrosis caused by Cytospora balanejica sp. nov. in Iran

Abstract Apple is the most important fruit tree in West Azarbaijan province of Iran. In a survey of apple orchards, a disease with crown and collar canker and necrosis symptoms was observed in three young apple orchards in Urmia, affecting 15% and 1% of ‘Red Delicious’ and ‘Golden Delicious’ cultivars, respectively. A fungus with typical characteristics of the asexual morph of Cytospora was regularly isolated from the diseased tissues. Morphological characteristics and phylogenetic analyses inferred from the combined dataset of the ITS-rDNA, parts of LSU, tef1-α, rpb2, and act1 genes revealed that the isolates represent a new species of Cytospora, described herein as Cytospora balanejica sp. nov.. The pathogenicity of all isolates was confirmed on apple cv. ‘Red Delicious’ based on Koch’s postulates. Also, the reaction of 12 other apple cultivars was assessed against five selected isolates with the highest virulence. The results showed that except for cv. ‘Braeburn’, which did not produce any symptoms of the disease, the other 11 cultivars showed characteristic disease symptoms including sunken and discolored bark and wood. The mean length of the discolored area was different among the 11 so-called susceptible cultivars, hence cvs. ‘M4’ and ‘Golden Delicious’ showed the highest and the lowest lesion length, respectively. Moreover, the aggressiveness of the five tested isolates was different, and the isolates BA 2-4 and BA 3-1 had the highest and lowest aggressiveness, respectively. Based on our observations on the potential ability of the fungus to cause disease on young and actively growing apple trees, it will be a serious threat to apple cultivation and industry

Insekticidna aktivnost in subletalni učinki izolatov entomopatogene glive Beauveria bassiana (Bals.-Criv.) Vuill. in eteričnih olj na bombaževo uš (Aphis gossypii Glover, 1877, Hemiptera: Aphididae)

The cotton aphid, Aphis gossypii Glover, 1877, is a polyphagous species and one of the most important pests of cucumber crops in Iran. In this study, virulence of three Beauveria bassiana (Bals.-Criv.) Vuill isolates, IRAN 108, IRAN 429C and LRC 137, as well as insecticidal activity of two essential oils extracted from Matricaria chamomilla L. and Cuminum cyminum L. were evaluated against adult stage of A. gossypii under laboratory conditions. The data for life table were analyzed using the age-stage, two-sex life table theory. Results showed that all isolates were pathogenic on aphid, but their virulence was varied in different isolates. The lowest calculated LC50 was belonged to IRAN 429C (3.9 × 104conidia ml-1). The lowest LT50 was obtained at concentration of 108 and 107 conidia ml-1 for IRAN 429C (2.9 and 3.55 days, respectively). M. chamomilla essential oil had the lowest LC50 and LT50 values (19 µl l-1 air and 11.4 h), respectively. Longevity and population growth parameters, including the intrinsic rate of increase (rm), gross reproduction rate (GRR), net reproductive rate (R0), generation time (T) and finite rate of population increase (λ), were affected negatively by both agents. According to the results obtained in this study, both entomopathogenic fungi and essential oils could be used as an alternative to chemical insecticides in aphid IPM programs.Bombaževa uš (Aphis gossypii Glover, 1877) je polifagna vrsta in je eden izmed najpomembnejših škodljivcev kumar v Iranu. V raziskavi so bili preučevani virulenca izolatov entomopatogene glive (Beauveria bassiana (Bals.-Criv-) Vuill.) IRAN 108, IRAN 429C and LRC 137 in insekticidna aktivnost dveh eteričnih olj ekstrahiranih iz vrst Matricaria chamomilla L. in Cuminum cyminum L. na odrasle osebke bombaževe uši v laboratorijskih razmerah. Podatki preživetja so bili analizirali glede na starost, spol in razvojne faze škodljivca. Podatki so pokazali, da so bili vsi izolati patogeni za uši, vendar se je virulenca med izolati razlikovala. Najmanjša izračunana vrednost LC50 je pripadala izolatu IRAN 429C (3,9 × 104konidijev ml-1). Najmanjša vrednost LT50 je bila dosežena pri koncentracijah 108 in 107 konidijev ml-1 za izolat IRAN 429C (2,9 in 3,55 dni). Eterično olje prave kamilice je imelo najmanjše vrednosti LC50 in LT50 (19 µl l-1 zraka in 11,4 h). Preživetje in parametri rasti populacije kot so potencialna rast populacije (rm), bruto reprodukcija (GRR), neto reprodukcija (R0), čas med dvema zaporednima generacijama (T) in končna velikost povečanja populacije (λ) so bili negativno prizadeti pri obeh obravnavanjih. Glede na rezultate pridobljene v tej raziskavi, bi kot alternativo kemičnim insekticidom v programih intergriranega upravljanja z listnimi ušmi lahko uporabili oboje, entomopatogene glive in eterična olja

Entomopatogena gliva, Lecanicillium lecanii R. Zare & W. Gams, vključena v MCM-41: Novi učinkoviti bio-insekticid za zatiranje mokaste kapusove uši (Brevicoryne brassicae (Linnaeus, 1758) (Hom: Aphididae)) pri zaščiti zelja

Brevicoryne brassicae is a significant pest of cultivated cabbages and vegetable crops in the world. The present study was carried out to examine a potential strategy to enhance the insecticidal activity of Lecanicillium lecanii for cost-effective management of B. brassicae. The insecticidal efficacy of pure entomopathogenic fungus (PEF) and MCM-41 (Mobil Composition of Matter) L. lecanii were assessed against the cabbage aphid under laboratory and greenhouse conditions. The fungus was supported on MCM-41 and was completely characterized by Scanning Electron Microscope (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) techniques. LC50 values of PEF and MCM-41@fungus were 1.9×106 and 2.5×104 and 2.0×107 and 2.0×105 conidia/ml on adults of B. brassicae under laboratory and greenhouse conditions, respectively. Bioassays demonstrated that MCM-41@fungus significantly decreased LC50 values of entomopathogenic fungus and it was more toxic than L. lecanii at adult stage of the pest. The results showed that pure L. lecanii and its nano-formulation could play key roles as bio-pesticides in B. brassicae management programs.Mokasta kapusova uš (Brevicoryne brassicae) je pomemben škodljivec zelja in drugih zelenjadnic širom po svetu. Raziskava je bila izvedena za preučitev potencialne strategije povečanja insekticidne aktivnosti glive Lecanicillium lecanii za učinkovito in poceni zatiranje mokaste kapusove uši. Insekticidna učinkovitost čistega pripravka entomopatogene glive (PEF) in njene vključitve v MCM-41 (Mobil Composition of Matter)@L. lecanii) je bila ocenjena na kapusovi mokasti uši v laboratoriju in v rastlinjaku. Gliva, ki je bila vključena v MCM-41 je bila podrobno opisana z vrstičnim elektronskim mikroskopom (SEM), termogravimetrično analizo (TGA) in Fourierjevo transformacijsko unfrardečo tehniko (FT-IR). LC50 vrednosti za odrasle osebke mokaste kapusove uši so bile za PEF in MCM-41@gliva 1,9×106 in 2,5×104 ter 2,0×107 in 2,0×105 konidijev/ml v laboratoriju, oziroma rastlinjaku. Biotest je pokazal, da je kombinacija MCM-41@gliva značilno zmanjšala LC50 vrednosti entomopatogene glive in, da je bila bolj toksična za odrasle uši kot gliva sama. Rezultati so pokazali, da lahko imajo čiste kulture glive L. lecanii in njeni nano pripravki ključno vlogo kot biopesticidi v programih biološkega uravnavanja mokaste kapusove uši

Composition, Antifungal, Phytotoxic, and Insecticidal Activities of Thymus kotschyanus Essential Oil

Essential oils (EOs) are some of the outstanding compounds found in Thymus that can exert antifungal, phytotoxic, and insecticidal activities, which encourage their exploration and potential use for agricultural and food purposes. The essential oils (EO) obtained from Thymus kotschyanus collected in the East Azerbaijan Province (Iran) were characterized using a gas chromatography-mass spectrometry (GC-MS) analysis. Thymol was the most important compound (60.48%), although 35 other active compounds were identified in the EO. Significant amounts of carvacrol (3.08%), p-cymene (5.56%), and γ-terpinene (6.67%) were found in the EO. The T. kotschyanus EO was tested against important phytopathogenic fungi (Botrytis cinerea, Aspergillus niger, and Penicillium expansum). The antifungal assay showed that the use of ≥500 ppm of EO resulted in a fungicidal effect against all funguses tested. In a similar way, the use of ≥500 ppm of EO inhibited the germination of all crop weed seeds (Amaranthus retroflexus L. and Panicum miliaceum L.) and their subsequent growth, which demonstrated its herbicidal effect. Finally, the insecticidal capacity of T. kotschyanus EO was also observed against selected insects (Oryzaephilus surinamensis and Sitophilus oryzae). O. surinamensis was more susceptible to the effect of EO (LC50 = 4.78 µL/L air) than S. oryzae (LC50 = 13.20 µL/L air). The obtained results of the present study can provide new safe resources to the development of new products for the food, agriculture, and pharmaceutical industries