Characterization of a Chickpea Mutant Resistant to Phelipanche aegyptiaca Pers. and Orobanche crenata Forsk

Chickpea (Cicer arietinum L.) is a major pulse crop in Israel grown on about 3000 ha spread, from the Upper Galilee in the north to the North-Negev desert in the south. In the last few years, there has been a gradual increase in broomrape infestation in chickpea fields in all regions of Israel. Resistant chickpea cultivars would be simple and effective solution to control broomrape. Thus, to develop resistant cultivars we screened an ethyl methanesulfonate (EMS) mutant population of F01 variety (Kabuli type) for broomrape resistance. One of the mutant lines (CCD7M14) was found to be highly resistant to both Phelipanche aegyptiaca and Orobanche crenata. The resistance mechanism is based on the inability of the mutant to produce strigolactones (SLs)—stimulants of broomrape seed germination. LC/MS/MS analysis revealed the SLs orobanchol, orobanchyl acetate, and didehydroorobanchol in root exudates of the wild type, but no SLs could be detected in the root exudates of CCD7M14. Sequence analyses revealed a point mutation (G-to-A transition at nucleotide position 210) in the Carotenoid Cleavage Dioxygenase 7 (CCD7) gene that is responsible for the production of key enzymes in the biosynthesis of SLs. This nonsense mutation resulted in a CCD7 stop codon at position 70 of the protein. The influences of the CCD7M14 mutation on chickpea phenotype and chlorophyll, carotenoid, and anthocyanin content were characterized.

QTL dissection and mining of candidate genes for Ascochyta fabae and Orobanche crenata resistance in faba bean (Vicia faba L.)

Background Ascochyta blight caused by Ascochyta fabae Speg. and broomrape (Orobanche crenata) are among the economically most significant pathogens of faba bean. Several QTLs conferring resistance against the two pathogens have been identified and validated in different genetic backgrounds. The aim of this study was to saturate the most stable QTLs for ascochyta and broomrape resistance in two Recombinant Inbred Line (RIL) populations, 29H x Vf136 and Vf6 x Vf136, to identify candidate genes conferring resistance against these two pathogens. Results We exploited the synteny between faba bean and the model species Medicago truncatula by selecting a set of 219 genes encoding putative WRKY transcription factors and defense related proteins falling within the target QTL intervals, for genotyping and marker saturation in the two RIL populations. Seventy and 50 of the candidate genes could be mapped in 29H x Vf136 and Vf6 x Vf136, respectively. Besides the strong reduction of the QTL intervals, the mapping process allowed replacing previous dominant and pedigree-specific RAPD flanking markers with robust and transferrable SNP markers, revealing promising candidates for resistance against the two pathogens. Conclusions Although further efforts in association mapping and expression studies will be required to corroborate the candidate genes for resistance, the fine-mapping approach proposed here increases the genetic resolution of relevant QTL regions and paves the way for an efficient deployment of useful alleles for faba bean ascochyta and broomrape resistance through marker-assisted breeding.

Anti-Candidal Activity of the Parasitic Plant Orobanche crenata Forssk

Candida albicans (C. albicans) and Candida glabrata (C. glabrata) are part of the human microbiome. However, they possess numerous virulence factors, which confer them the ability to cause both local and systemic infections. Candidiasis can involve multiple organs, including the eye. In the present study, we investigated the anti-candidal activity and the re-epithelizing effect of Orobanche crenata leaf extract (OCLE). By the microdilution method, we demonstrated an inhibitory effect of OCLE on both C. albicans and C. glabrata growth. By crystal violet and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, we showed the ability of OCLE to inhibit the biofilm formation and the viability of yeast cells, respectively. By germ tube and adhesion assays, we proved the capacity of OCLE to affect the morphological transition of C. albicans and the adhesion of both pathogens to human retinal pigment epithelial cells (ARPE-19), respectively. Besides, by MTT and wound healing assay, we evaluated the cytotoxic and re-epithelizing effects of OCLE on ARPE-19. Finally, the Folin–Ciocalteu and the ultra-performance liquid chromatography-tandem mass spectrometry revealed a high content of phenols and the presence of several bioactive molecules in the extract. Our results highlighted new properties of O. crenata, useful in the control of Candida infections.

GBS analysis of Orobanche crenata populations in Algeria supports local adaptation and host-specialization

Crenate broomrape (Orobanche crenata Forsk.) is a serious long-standing parasitic weed problem in Algeria, mainly affecting legumes but also vegetable crops. Unresolved questions for parasitic weeds revolve around the extent to which these plants undergo local adaptation, especially with respect to host specialization, which would be expected to be a strong selective factor for obligate parasitic plants. In the present study, the Genotyping-By-Sequencing (GBS) approach was used to analyze genetic diversity and population structure of 10 Algerian O. crenata populations with different geographical origins and host species (faba bean, pea, chickpea, carrot and tomato). In total, 8,004 high-quality single-nucleotide polymorphisms were obtained and used across the study. Genetic diversity and relationships of 95 individuals from 10 populations were studied using model-based ancestry analysis, principal components analysis, discriminant analysis of principal components, and phylogeny approaches. The genetic differentiation (FST) between pairs of populations was lower between adjacent populations and higher between geographically separated ones, but no support was found for isolation by distance. Further analyses identified four genetic clusters and revealed evidence of structuring among populations and hosts with more evident structuring among hosts than strictly along a geographic gradient. In the most striking example, O. crenata growing on pea had a distinct SNP profile from those growing on faba bean or other crops. These results illustrate the potential of GBS to reveal the dynamics of parasitic weed dispersal and adaptation.

Resistance against Orobanche crenata in Bitter Vetch (Vicia ervilia) Germplasm Based on Reduced Induction of Orobanche Germination

Bitter vetch (Vicia ervilia (L.) Willd.) is a legume well adapted to cultivation in marginal areas, being an important source of protein for animal feed in low input cropping systems. Surprisingly, it is an underutilized crop as it could be a good alternative to increase the sustainability of extensive rainfed cropping systems. In Mediterranean rainfed cropping systems, the productivity of bitter vetch is severely reduced by the parasitic weed species Orobanche crenata (Forsk). To date, few resistant bitter vetch genotypes have been identified. O. crenata infection process initiates with the recognition of germination factors exuded by roots of susceptible hosts. In this work, the interaction of a collection of bitter vetch accessions and O. crenata has been analyzed in order to discover accessions with low germination induction activity. Through a combination of field and rhizotron experiments, two bitter vetch accessions were selected showing low germination-induction activity, which resulted in less infection. In addition, in vitro germination assays revealed that the low germination activity was due to low exudation of germination factors and not due to the exudation of germination inhibitors. The selected low germination-inducers genotypes could be the basis for a new breeding program generating locally adapted alternatives with resistance to O. crenata.

Development of Pea Breeding Lines with Resistance to Orobanche crenata Derived from Pea Landraces and Wild Pisum spp.

Pea (Pisum sativum) is an important grain legume worldwide whose cultivation is severely constrained by the root parasitic weed crenate broomrape (Orobanche crenata), which is widespread in the Mediterranean Basin and Middle East. No resistance is available in commercialized cultivars but some levels of incomplete resistance has been reported in pea landraces and Pisum spp. relatives. In this paper we report the development of a number of advanced pea breeding lines with resistance derived from wide crosses with resistant P. fulvum, P. sativum ssp. elatius, P. sativum ssp. syriacum, and with pea landraces, and critically discuss current progress and future perspectives on pea breeding for broomrape resistance. Resistance of breeding lines was confirmed over five field trials, showing markedly reduced broomrape over ground emergence, and in rhizotron experiments, showing either reduced tubercle formation or, in some of the lines, also hampered tubercle development that might grow slower or even become necrotic and die. Breeding lines performed well agronomically, having similar or mostly higher yields than the parental pea cv. Messire in environments with high broomrape incidence.

Siirt'te Doğal Yayılış Gösteren Parazit Yabancı Otlar ve Konukçuları

Bitkisel üretimde ekonomik verim kaybına neden olan en önemli faktörlerden birisi de yabancı otlardır. Yabancı otlar kültür bitkileri ile rekabete girerek ve allelopatik etkileri ile kültür bitkilerini olumsuz etkilemeleri yanında kültür bitkileri üzerinde parazit olarak yaşamak suretiyle verim ve kalite kayıplarına neden olmaktadırlar. Çalışma ile Siirt ili genelinde görülen parazitik yabancı ot türlerinin ve rastlanma sıklıklarının belirlenmesi amaçlanmıştır. Sürvey çalışmaları 2018-2019 yıllarında ve ili temsil edecek şekilde toplam 105 noktada yürütülmüştür. Çalışmalar sonucunda tam parazitik karekter gösteren Orabanche cinsine ait 3 tür (Orobanchea egyptiaca Pers., Orobanche crenata Forssk. ve Orobanche ramosa L.), Cuscuta cinsine dahil 2 tür (Cuscuta approximata Bab., Cuscuta campestris Yunck.) saptanmıştır. Ayrıca bölgede ormanlık alanlarda meşe türlerinde sorun olan ve yarı parazitik nitelik gösteren Viscum album L. ve Loranthus europaeus Jacq. türlerine de rastlanmıştır. Bölgede belirlenen parazitik yabancı otlara konukçuluk yapan kültür bitkileri ile yabancı otlar da listelenmiştir. Tarımsal açıdan Orobanche türlerine özellikle mercimek ve domates tarlalarında sıklıkla rastlandığı ve önemli düzeyde ekonomik kayıplara neden oldukları saptanmıştır. Bölgede parazit yabancı otlardan kaynaklanan verim kayıplarının önlenmesi için entegre yabancı ot idare stratejilerine ihtiyaç duyulduğu görülmüştür. Ancak üreticilerin konuya ilişkin bilgi birikimlerindeki eksiklik dikkate alınarak öncelikle konuya ilişkin yayım çalışmalarının öncelikle yapılması gerektiği kanaatine varılmıştır.