CRISPR/Cas9-mediated mutagenesis of CAROTENOID CLEAVAGE DIOXYGENASE 8 in tomato provides resistance against the parasitic weed Phelipanche aegyptiaca.

Broomrapes (Phelipanche aegyptiaca and Orobanche spp.) are obligate plant parasites that cause extreme damage to crop plants. The parasite seeds have strict requirements for germination, involving preconditioning and exposure to specific chemicals strigolactones [SLs] exuded by the host roots. SLs are plant hormones derived from plant carotenoids via a pathway involving the Carotenoid Cleavage Dioxygenase 8 (CCD8). Having no effective means to control parasitic weeds in most crops, and with CRISPR/Cas9 being an effective gene-editing tool, here we demonstrate that CRISPR/Cas9-mediated mutagenesis of the CCD8 gene can be used to develop host resistance to the parasitic weed P. aegyptiaca. Cas9/single guide (sg) RNA constructs were targeted to the second exon of CCD8 in tomato (Solanum lycopersicum L.) plants. Several CCD8Cas9 mutated tomato lines with variable insertions or deletions in CCD8 were obtained with no identified off-targets. Genotype analysis of T1 plants showed that the introduced CCD8 mutations are inherited. Compared to control tomato plants, the CCD8Cas9 mutant had morphological changes that included dwarfing, excessive shoot branching and adventitious root formation. In addition, SL-deficient CCD8Cas9 mutants showed a significant reduction in parasite infestation compared to non-mutated tomato plants. In the CCD8Cas9 mutated lines, orobanchol (SL) content was significantly reduced but total carotenoids level and expression of genes related to carotenoid biosynthesis were increased, as compared to control plants. Taking into account, the impact of plant parasitic weeds on agriculture and difficulty to constitute efficient control methods, the current study offers insights into the development of a new, efficient method that could be combined with various collections of resistant tomato rootstocks

Aportaciones y correcciones al género Orobanche (Orobanchaceae) en Andalucía.

Contributions and corrections to the genus Orobanche (Orobanchaceae) in Andalusia.Palabras clave: Cádiz, Orobanche, parásita, UICN.Key words: Cadiz, IUCN, Orobanche, parasite

"Orobanche mariana" A. Pujadas (Orobanchaceae) sp. nov. para el sur de la Península Ibérica

Orobanche mariana A. Pujadas (Orobanchaceae) sp. nov. from the south of the Iberian Peninsula. Palabras clave. Flora iberica, jopo, Orobanchaceae, Orobanche, parásita.Key words. Broomrape, Flora iberica, Orobanchaceae, Orobanche, parasite

The response of two legume crops (hyacinth bean and Kidney bean) to the parasitism of field dodder (_Cuscuta campestris_)

Abstract: Microscopic examinations and chemical studies were performed to study the response of two legume crops, hyacinth bean (_Lablab purpureus L._) Sweet and kidney bean (_phaseolus vulgaris L._) to the filed dodder (FD) (_Cuscuta campestris Yuncker_) parasitism. Hyacinth bean, showing no effective resistance mechanisms,was found to be a highly susceptible host to FD. However, kidney bean, displaying resistant reactions towards the parasitism of FD,was found to be an incompatible host.The possible reasons for the resistance of kidney bean to FD were anatomical (hypersensitivity) and chemical (high contents of phenolic acids and lignin) stimulated defence mechanisms, which developed during the actual intrusion of FD haustorial cells inside its tissues

Orobanche cohenii (Orobanchaceae) a new species from Israel

Orobanche cohenii a new species belonging to Orobanche sect. Trionychon is described and illustrated from Mt. Hermon, Israel. Its relationships with the other species of Orobanche sect. Trionychon occurring in this area are examined

Next-generation sequencing reveals the impact of repetitive DNA in phylogenetically closely related genomes of Orobanchaceae

We used next-generation sequencing to characterize the genomes of nine species of Orobanchaceae of known phylogenetic relationships, different life forms, and including a polyploid species. The study species are the autotrophic, nonparasitic Lindenbergia philippensis, the hemiparasitic Schwalbea americana, and seven nonphotosynthetic parasitic species of Orobanche (Orobanche crenata, Orobanche cumana, Orobanche gracilis (tetraploid), and Orobanche pancicii) and Phelipanche (Phelipanche lavandulacea, Phelipanche purpurea, and Phelipanche ramosa). Ty3/Gypsy elements comprise 1.93%–28.34% of the nine genomes and Ty1/Copia elements comprise 8.09%–22.83%. When compared with L. philippensis and S. americana, the nonphotosynthetic species contain higher proportions of repetitive DNA sequences, perhaps reflecting relaxed selection on genome size in parasitic organisms. Among the parasitic species, those in the genus Orobanche have smaller genomes but higher proportions of repetitive DNA than those in Phelipanche, mostly due to a diversification of repeats and an accumulation of Ty3/ Gypsy elements. Genome downsizing in the tetraploid O. gracilis probably led to sequence loss across most repeat types

Le Piante endemiche della Sardegna: 106-109

Si descrivono: Orobanche denudata, Orobanche rigens, Crocus minimus, geofite, e Ptychotis sardoa, emicriptofita rosulata

Orobanche L. (Orobanchaceae) sect. Trionychon Wallr., en Andalucía II: Orobanche rosmarina Beck.

RESUMEN. Orobanche L. (Orobanchaceae) sect. Trionychon Wallr., en Andalucía II: Orobanche rosmarina Beck. Se indica la presencia de Orobanche rosmarina Beck en Andalucía. Aportamos la descripción de los ejemplares andaluces, su corología y habitat. Se incluyen unas nuevas claves de determinación para las especies andaluzas de la sect Trionychon.Palabras clave. Orobanchaceae, Orobanche, jopo, parásito, Andalucía.ABSTRACT. Orobanche L. (Orobanchaceae) sect. Trionychon Wallr., in Andalusia II: Orobanche rosmarina Beck. The presence of Orobanche rosmarina Beck in Andalusia is noted. Description, chorology and habitat of the Andalusian specimens is given. New identification keys are added.Key words. Orobanchaceae, Orobanche, broomrape, parasite, Andalusia

Strigolactone biosynthesis is evolutionarily conserved, regulated by phosphate starvation and contributes to resistance against phytopathogenic fungi in a moss, Physcomitrella patens

In seed plants, strigolactones (SLs) regulate architecture and induce mycorrhizal symbiosis in response to environmental cues. SLs are formed by combined activity of the carotenoid cleavage dioxygenases (CCDs) 7 and 8 from 9-cis-β-carotene, leading to carlactone that is converted by cytochromes P450 (clade 711; MAX1 in Arabidopsis) into various SLs. As Physcomitrella patens possesses CCD7 and CCD8 homologs but lacks MAX1, we investigated if PpCCD7 together with PpCCD8 form carlactone and how deletion of these enzymes influences growth and interactions with the environment. We investigated the enzymatic activity of PpCCD7 and PpCCD8 in vitro, identified the formed products by high performance liquid chromatography (HPLC) and LC-MS, and generated and analysed ΔCCD7 and ΔCCD8 mutants. We defined enzymatic activity of PpCCD7 as a stereospecific 9-cis-CCD and PpCCD8 as a carlactone synthase. ΔCCD7 and ΔCCD8 lines showed enhanced caulonema growth, which was revertible by adding the SL analogue GR24 or carlactone. Wild-type (WT) exudates induced seed germination in Orobanche ramosa. This activity was increased upon phosphate starvation and abolished in exudates of both mutants. Furthermore, both mutants showed increased susceptibility to phytopathogenic fungi. Our study reveals the deep evolutionary conservation of SL biosynthesis, SL function, and its regulation by biotic and abiotic cues.Deutsche Forschungsgemeinschaft AL892/1-4Academy of Finland 125312

Does abscisic acid affect strigolactone biosynthesis?

Strigolactones are considered a novel class of plant hormones that, in addition to their endogenous signalling function, are exuded into the rhizosphere acting as a signal to stimulate hyphal branching of arbuscular mycorrhizal (AM) fungi and germination of root parasitic plant seeds. Considering the importance of the strigolactones and their biosynthetic origin (from carotenoids), we investigated the relationship with the plant hormone abscisic acid (ABA). Strigolactone production and ABA content in the presence of specific inhibitors of oxidative carotenoid cleavage enzymes and in several tomato ABA-deficient mutants were analysed by LC-MS/MS. In addition, the expression of two genes involved in strigolactone biosynthesis was studied. * • The carotenoid cleavage dioxygenase (CCD) inhibitor D2 reduced strigolactone but not ABA content of roots. However, in abamineSG-treated plants, an inhibitor of 9-cis-epoxycarotenoid dioxygenase (NCED), and the ABA mutants notabilis, sitiens and flacca, ABA and strigolactones were greatly reduced. The reduction in strigolactone production correlated with the downregulation of LeCCD7 and LeCCD8 genes in all three mutants. * • The results show a correlation between ABA levels and strigolactone production, and suggest a role for ABA in the regulation of strigolactone biosynthesis