Root Holoparasite Research Articles

The metabolic profiles of phenolic acids and aromatic amino acids in the Orobanche crenata parasite and its host faba bean at different infestation stages

Orobanche crenata is a root holoparasite that depends on its host for nutritional requirements. The shikimate pathway that metabolizes about 30% of the assimilated carbon in photosynthetic plants plays a role in host-parasite relationships. Aromatic amino acids (AAAs) and phenolic acids are derived from the shikimate pathway and serve as precursors of a wide number of primary and secondary metabolites. The effects of the O. crenata parasite on the phenolic acid and AAA profiles of two faba bean varieties and the differences of these compounds between the host organs and attached parasite at infestation stages were studied. Hosts and attached parasites were collected and divided, depending on the stage of parasite development, into four stages. The results revealed that phenolic acids and free AAAs tended to increase in parasitized roots compared to those of healthy roots, and the greatest increase in phenolic contents occurred at the first infestation stage. Syringic acid was observed to be unique to the parasite. Profiles of phenolic acids and AAAs were changed during the developmental stages of the parasite and differed from those of its host. Caffeic in the parasite reached more than 100 times that in Nubaria 4 host roots at the fourth infestation stage. Free phenylalanine in the parasite ranged between 2.2 and 5.5 times its level in host roots at all infestation stages. This study provides much evidence that indicates O. crenata is able to self-regulate its phenolic and AAA metabolites during its developmental stages, which differ from those of its host.

Unlocking the secrets of parasitic plants: A comparative study of the development and floral morphoanatomy of Pholisma (Lennoaceae)

Pholisma belongs to the family Lennoaceae, classified as obligate root holoparasites. Most existing studies are limited to addressing only P. arenarium. In this study, morphoanatomical and developmental aspects of flowers of the three species comprising Pholisma are described using histological embedding techniques in Paraplast and LR- White and observations by light microscopy and scanning electron microscopy. Similarities found in the three species include the presence of trichomes on the sepals, each carpel folding independently. Each carpel has transmitting tissue, and an empty cavity is distinguished in the centre of the style. The stigma is crateriform and of the wet type. Sporogenesis, gametogenesis, and floral development follow a similar pattern in the three species. Differences among species include the position of the stamens, pollen morphology, type of inflorescence, and colour of flowers and inflorescences. In P. arenarium, the stamens are located below the stigma height, and the pollen is tetracolporate and psilate; in P. sonorae, the stamens are at the same height as the stigma, and the pollen is tricolporate and reticulate; and in P. culiacana, the stamens are above the stigma height, and the pollen is tricolporate and psilate. The inflorescences in both P. arenarium and P. sonorae are cymes; the corolla colour is white with purple lines extending from the limb to the corolla tube. In contrast, the inflorescence in P. culiacana is a capitulum type, and the corolla colour is white with pink margins. The characters found in the three species of Pholisma are compared with some genera comprising the family Ehretiaceae.

Unlocking the hepatoprotective potential of the parasitic plant Orobanche foetida Poir. aqueous extract against CCl4-induced liver injury in rat.

In this current study, we explored the preventive capacity of the aqueous extract of Orobanche foetida (OF), a root holoparasite, against CCl4 prompt hepatotoxicity in rats. LC-MS/MS profiling revealed the existence of 32 compounds belonging to organic acids, benzoic acid derivatives, and hydroxycinnamic acids along with their glycosides and derivatives as well as several flavonoids. In vitro, OF demonstrated substantial antioxidant potential at DPPH and ABTS assays. Results showed that the pretreatment with OF for 6weeks at the doses (25mg/kg bw) and (50mg/kg bw) countered the CCl4-induced liver injury by restoring liver injuries indicators (ALT, AST, LDH, ALP, GGT and bilirubin), normalizing lipid profile (TC, TG, LDL-C, and HDL-C), as well as, impeding DNA fragmentation. Furthermore, OF blocked the hepatic oxidative stress spurred by CCl4 administration through boosting antioxidant enzymes (GSH, CAT, and SOD) responsible of diminishing lipid peroxidation. exhibited an anti-inflammatory effect by downregulating TNF-α and IL-6 levels. OF suppressive effect on proinflammatory cytokines is further exerted by its capacity to modulate the expression of the NF-κB gene. In silico investigation revealed that among the 32 identified compounds, vanillic acid glucoside and dihydroxybenzoic acid glucoside have strong and stable bindings with the active sites of three key inflammatory proteins (PARP-1, TNF-α, IL-6), which could highlight the antioxidant and anti-inflammatory capacity of. Overall, this research provides a preliminary pharmacological support for the medicinal applications of Orobanche foetida for addressing inflammatory and hepato-pathological conditions.

First Report of Orobanche cumana on Coleus in Xinjiang, China.

Coleus (Plectranthus scutellarioides [L.] R.Br., [syn.: Solenostemon scutellarioides], Lamiaceae) is a popular ornamental plant for its colorful and showy foliage, and widely planted as a garden plant, and a medicinal herb in some countries, including India, Indonesia, Mexico (Zhu et al. 2015). In March 2022, parasitism of broomrape, on coleus plants was found in a greenhouse (86° 3' 36" E, 44° 18' 36" N, 500 m elevation) at Shihezi University, Xinjiang, China. A few plants (6%) were parasitized with 2.5 emerged broomrape shoots per host plant. The host-parasite connection was confirmed by microscopy. Morphological characteristics of the host were consistent with coleus described by Cao et al. (2023). The broomrapes were: stem simple and slender, slightly bulbous at the base, glandular-pubescent; inflorescence usually many-flowered, lax, dense in the upper third; bracts 8 to 10 mm long, ovate-lanceolate; calyx segments free, entire, seldom bifid with markedly unequal subulate teeth; corolla markedly curvate, dorsal line inflected, white at the base, bluish violet in the upper part; stamens adaxial with filaments 6 to 7 mm long; abaxial stamens with filaments 7 to 10 mm long; gynoecium 7 to 10 mm long; ovary 4 to 5 mm long, glabrous; style with short glandular hairs; stigma white, keyed to sunflower broomrape (Orobanche cumana Wallr.) (Pujadas-Salvà and Velasco 2000). Total genomic DNA of this parasite flowers was extracted and the trnL-F gene and ribosomal DNA internal transcribed spacer (ITS) region were amplified using the primer pairs C/F and ITS1/ITS4, respectively (Taberlet et al. 1991; Anderson et al. 2004). Sequences of ITS (655 bp) and trnL-F (901 bp) were obtained (GenBank ON491818 and ON843707). BLAST analysis showed the ITS sequence was identical to that of sunflower broomrape (MK567978.1), also the trnL-F sequence matched that of sunflower broomrape (MW809408.1, identity 100%). Multi-locus phylogenetic analyses of the two sequences showed this parasite is clustered with sunflower broomrape. Together, morphological and molecular evidences confirmed the parasite on coleus plants was sunflower broomrape, a root holoparasitic plant with a narrow host range, which mainly posed a devastating threat to sunflower planting industry (Fernández-Martínez et al. 2015). To verify that coleus sunflower broomrape parasitic association, seedlings of this host were planted in 1.5-L pots containing compost-vermiculite-sand mixture (1:1:1 v:v:v) and sunflower broomrape seeds (50 mg seeds per 1 kg, soil). Three coleus seedlings, transplanted into pots without sunflower broomrape seeds, served as control. Ninety-six days later, the infected plants were smaller, their leaf color was observed to a lighter green than those of control plants and were similar to the broomrape-infected coleus plants observed in the greenhouse. The coleus roots with sunflower broomrape were carefully washed with running water, 10 to 15 emerged broomrape shoots and 14 to 22 underground attachments were observed on the coleus roots. The parasite grew well in coleus roots, from germination, attachment to host roots, and tubercles development. At the tubercle stage, the endophyte of sunflower broomrape had connected with the vascular bundle of the coleus root, confirming the sunflower broomrape-coleus connection. To the best of our knowledge, this was the first report of sunflower broomrape parasitizing coleus in Xinjiang, China. This indicates that sunflower broomrape can be propagated and survived by coleus, in fields or greenhouses with sunflower broomrape. To limit the spread of sunflower broomrape, preventive field management is needed for the coleus farmlands and greenhouse where the root holoparasite is prevalent.

Balanophora genomes display massively convergent evolution with other extreme holoparasites and provide novel insights into parasite-host interactions.

Parasitic plants have evolved to be subtly or severely dependent on host plants to complete their life cycle. To provide new insights into the biology of parasitic plants in general, we assembled genomes for members of the sandalwood order Santalales, including a stem hemiparasite (Scurrula) and two highly modified root holoparasites (Balanophora) that possess chimaeric host-parasite tubers. Comprehensive genome comparisons reveal that hemiparasitic Scurrula has experienced a relatively minor degree of gene loss compared with autotrophic plants, consistent with its moderate degree of parasitism. Nonetheless, patterns of gene loss appear to be substantially divergent across distantly related lineages of hemiparasites. In contrast, Balanophora has experienced substantial gene loss for the same sets of genes as an independently evolved holoparasite lineage, the endoparasitic Sapria (Malpighiales), and the two holoparasite lineages experienced convergent contraction of large gene families through loss of paralogues. This unprecedented convergence supports the idea that despite their extreme and strikingly divergent life histories and morphology, the evolution of these and other holoparasitic lineages can be shaped by highly predictable modes of genome reduction. We observe substantial evidence of relaxed selection in retained genes for both hemi- and holoparasitic species. Transcriptome data also document unusual and novel interactions between Balanophora and host plants at the host-parasite tuber interface tissues, with evidence of mRNA exchange, substantial and active hormone exchange and immune responses in parasite and host.

Morphological studies on some Orobanche L. species in Egypt

Broomrapes are root holoparasites in the family Orobanchaceae. These parasites can cause substantial losses, 5%–95%, in important crops . These plants parasitize legumes, oilseeds, nightshades, and crucifers in warmer areas of Europe, Africa, the Americas, and Asia. A full taxonomic study for seven taxa of Orobanche in Egypt; O. ramose L. var. ramose, O. mutelii F. W., O. lavandulacea Rchb., O. aegyptiaca Pers., O. crenata Forssk., O. cernua Loefl., and O. minor Sm. var. minor is presented in this article. The work includes a key to taxa, taxa descriptions, LM and scanning electron microscopy (SEM) images of pollen, seed, and seed‐coat morphology, and a numerical analysis of results. Macromorphological characteristics are key features for differentiation among taxa. Diagnostic characteristics include simple and branched stems, presence and absence of bracteoles, constriction of corolla tubes, and color and length of corollas. SEM of pollen identified three types: prolate-spherical, oblate-spherical, and spherical. Three apertures were also recorded; inaperturate- tricolpate, tricolpate, and inaperturate. Ornamentation included only microreticulate and scabrate-verrucate. LM investigation of seeds recognized three shapes: ellipsoid to ovoid, ovoid to ellipsoid, and ovoid. SEM identified four morphological groups.

Diversity and communities of culturable endophytic fungi from the root holoparasite Balanophora polyandra Griff. and their antibacterial and antioxidant activities

PurposeBalanophora polyandra Griff. is a holoparasitic medicinal plant that produces compounds with antibacterial and antioxidant activities. Plant endophytic fungi are an abundant reservoir of bioactive metabolites for medicinal exploitation, and an increasing number of novel bioactive compounds are being isolated from endophytic fungi. The present study investigated the diversity of culturable endophytic fungi from the roots of holoparasite B. polyandra to explore active strains and metabolites. In addition, the antibacterial and antioxidant activities of 22 strains cultured from B. polyandra were also evaluated.MethodsThe endophytic fungi were identified according to their colony morphology and ITS-5.8S rDNA sequencing. TLC-MTT-Bioautography assays and DPPH radical scavenging assays were employed to assess the antibacterial and antioxidant activities of ethyl acetate extracts of the endophytic fungi.ResultsOne hundred and twenty-five endophytic strains were isolated from the roots of B. polyandra, including 70 from female samples and 55 from male samples. Of them, twenty-two distinct isolates representing 15 genera and 22 species based on their ITS-rDNA genomic sequence were successfully identified from female and male samples of B. polyandra. The genus Calonectria was the most prevalent genus, with a CF% of 18.3, followed by the genera Clonostachys and Botryosphaeria, with CF% values of 13.4 and 10.0, respectively. Interestingly, the fungal extracts exhibited broad-spectrum antibacterial activities against gram-positive and gram-negative bacteria, as well as potential antioxidant activities with IC50 values ranging from 0.45 to 6.90 mg/mL. Among them, endophytes Bpf-10 (Diaporthe sp.) and Bpf-11 (Botryosphaeria sp.) showed the strongest biological activities and more abundant secondary metabolites.ConclusionsThis study reported the diversity of endophytic fungi from the roots of B. polyandra and the antibacterial and antioxidant activities of the crude extracts for the first time. The results revealed that B. polyandra contains diverse culturable endophytic fungi that potentially produce natural antibacterial and antioxidant compounds with great value to the agriculture and pharmaceutical industries.

Inferring the biogeography of New Zealand’s only endemic holoparasitic plant, the threatened Dactylanthus taylorii (Mystropetalaceae)

ABSTRACT Despite a rich history of botanical research, little is known about the distribution of genetic variation within New Zealand plant species. With a native vascular flora that consists of ∼80% endemics, nearly one-half of which are threatened, there is a dire need for a better understanding of intraspecific diversity for individual plant species and of biogeographic patterns for the wider New Zealand flora. To these ends, we have investigated population genetic structure in the endemic root holoparasite, Dactylanthus taylorii (pua o te Rēinga, Mystropetalaceae). A total of 235 individuals from 31 locations across the North Island of New Zealand (Te Ika-a-Māui, Aotearoa) were genotyped for a suite of nuclear microsatellite loci. Genotype data were analysed at the individual and population levels to assess genetic diversity within and among populations and to investigate the geographic distribution of genetic variation within the species. Population structure was assessed using Bayesian clustering, discriminant analysis of principal components, and a Neighbor-Net analysis. A hierarchical pattern of genetic diversity was revealed, with evidence for three broad geographic regional groupings (West, East, and Central Volcanic Plateau (CVP)). Upon further analysis, each of the three geographic groups further subdivide hierarchically into two or three genetic subgroups. Genetic diversity was found to be relatively high in this endangered species but varies considerably across populations. The distribution of genetic groups appears to have been influenced by past volcanic activity as the CVP group is largely coincident with a distinct tephra isopach from the 1.8 ka Taupō eruption and the West and East groups may have diverged due to recurring volcanic activity in the Central Volcanic Zone. The genetic structure resolved here provides important information for the management of D. taylorii specifically and for our understanding of New Zealand biogeography generally.

How do holoparasitic plants exploit vitamin K1?

ABSTRACT Phylloquinone (vitamin K1) is a thylakoid-embedded electron carrier essential for photosynthesis. Paradoxically, we found that phylloquinone biosynthesis is retained in the nonphotosynthetic holoparasite Phelipanche aegyptiaca (Egyptian broomrape). The phylloquinone pathway genes are preferentially expressed during development of the invasive organ, the haustorium, and exhibit strong coexpression with redox-active proteins known to be involved in parasitism. Unlike in photoautotrophic taxa, the late pathway genes of the holoparasite lack the chloroplast-targeting sequence and their proteins are targeted to the plasma membrane instead. Plasma membrane phylloquinone may enable Phelipanche to sense changes in the redox environment during host interactions. The N-truncated isoforms are conserved in several other Orobanchaceae root holoparasites, and interestingly, in a number of closely related photoautotrophic species as well. This suggests an ancient origin of distinct phylloquinone pathways predating the evolution of parasitic plants in the Orobanchaceae. These findings represent exciting opportunities to probe plasma membrane phylloquinone function and diversification in parasitic and nonparasitic plant responses to external redox chemistry in the rhizosphere.

Plastomes in the holoparasitic family Balanophoraceae: Extremely high AT content, severe gene content reduction, and two independent genetic code changes

The transition to a heterotrophic lifestyle in angiosperms is characterized by convergent evolutionary changes. Plastid genome remodeling includes dramatic functional and physical reductions with the highest degrees observed in fully heterotrophic plants. Genes related to photosynthesis are generally absent or pseudogenized, while a few genes related to other metabolic processes that take place within the plastid are almost invariably maintained. The family Balanophoraceae consists of root holoparasites that present reduced plastid genomes with an extraordinarily elevated AT content and the single genetic code change ever documented in land plant plastomes (the stop codon TAG now codes for tryptophan). Here, we studied the plastomes of Lophophytum leandri and Ombrophytum subterraneum (Balanophoraceae) that showed the remarkable absence of the gene trnE, a highly biased nucleotide composition, and an independent genetic code change (the standard stop codon TGA codes for tryptophan). This is the second genetic code change identified in land plant plastomes. Analysis of the transcriptome of Lophophytum indicated that the entire C5 pathway typical of plants is conserved despite the lack of trnE in its plastome. A hypothetical model of plastome evolution in the Balanophoraceae is presented.

Culturable endophytic bacteria from Phelipanche ramosa (Orobanchaceae) seeds

AbstractEndophytic microbiomes play a beneficial role in the development and protection of plants. However, seed-borne endophytic bacteria have not yet been fully explored. Investigation of parasitic plants, whose existence depends on yet poorly understood and complicated relationships with microorganisms and hosts, is particularly crucial. Endophytic bacteria promote seed conservation and facilitate seed germination in soil. Several root holoparasites from the Orobanchaceae family are the most aggressive broomrape species, often causing serious yield losses in important crops. Parasitic plants are characterized by the production of a large number of some of the smallest seeds in the world's flora, allowing them to stay viable in the soil for several dozen years. This study's aim was to isolate and characterize the seed endophyte and surface bacteria of the most aggressive and widespread broomrape weed, Phelipanche ramosa. We isolated two endophytic bacteria from within the seeds which are closely related to Brevibacterium frigoritolerans and Bacillus simplex described as soil bacteria, highly resistant to environmental conditions, and as plant growth-promoting rhizobacteria. Moreover, we isolated three strains from the surface of non-sterile seeds; all three isolates were related to the Bacillus cereus group.

Scent chemistry and pollinators in the holoparasitic plant Cynomorium songaricum (Cynomoriaceae).

Holoparasitic plants are interesting heterotrophic angiosperms. However, carrion- or faeces-mimicking is rarely described for such plants. There is no information on the pollination biology of Cynomoriaceae, despite the fact that these plants are rare and vulnerable. This is the first study to reveal pollination in a member of this family, Cynomorium songaricum, a root holoparasite with a distinctive and putrid floral odour. From 2016 to 2018, we studied the floral volatiles, floral visitors and pollinators, behavioural responses of visitors to floral volatiles, breeding system, flowering phenology and floral biology of two wild populations of C. songaricum in Alxa, Inner Mongolia, China. A total of 42 volatiles were identified in inflorescences of C. songaricum. Among these volatiles are compounds known as typical carrion scents, such as p-cresol, indole, dimethyl disulphide and 1-octen-3-ol. C. songaricum is pollinated by various Diptera, such as Musca domestica, M. stabulans (Muscidae), Delia setigera, D. platura (Anthomyiidae), Lucilia sericata, L. caesar (Calliphoridae), Wohlfahrtia indigens, Sarcophaga noverca, S. crassipalpis and Sarcophila meridionalis (Sarcophagidae). The inflorescence scent of C. songaricum attracted these pollinators. The plants significantly benefit from insect pollination, although wind can be a pollen vector in the absence of pollinators. C. songaricum is a cross-pollinated, self-incompatible plant. Our findings suggest that C. songaricum releases malodorous volatiles to attract Diptera to achieve pollination. This new example lays the foundation for further comparative studies in other members of this plant group and contributes to a better understanding of fly-pollinated, carrion mimicking plants.

Unique bacterial assembly, composition, and interactions in a parasitic plant and its host.

How plant-associated microbiota are shaped by, and potentially contribute to, the unique ecology and heterotrophic life history of parasitic plants is relatively unknown. Here, we investigate the leaf and root bacterial communities of the root holoparasite Orobanche hederae and its host Hedera spp. from natural populations. Root bacteria inhabiting Orobanche were less diverse, had fewer co-associations, and displayed increased compositional similarity to leaf bacteria relative to Hedera. Overall, Orobanche bacteria exhibited significant congruency with Hedera root bacteria across sites, but not the surrounding soil. Infection had localized and systemic effects on Hedera bacteria, which included effects on the abundance of individual taxa and root network properties. Collectively, our results indicate that the parasitic plant microbiome is derived but distinct from the host plant microbiota, exhibits increased homogenization between shoot and root tissues, and displays far fewer co-associations among individual bacterial members. Host plant infection is accompanied by modest changes of associated microbiota at both local and systemic scales compared with uninfected individuals. Our results are a first step towards extending the growing insight into the assembly and function of the plant microbiome to include the ecologically unique but often overlooked guild of heterotrophic plants.

Extensive plastome reduction and loss of photosynthesis genes in Diphelypaea coccinea, a holoparasitic plant of the family Orobanchaceae.

BackgroundParasitic plants have the ability to obtain nutrients from their hosts and are less dependent on their own photosynthesis or completely lose this capacity. The reduction in plastid genome size and gene content in parasitic plants predominantly results from loss of photosynthetic genes. Plants from the family Orobanchaceae are used as models for studying plastid genome evolution in the transition from an autotrophic to parasitic lifestyle. Diphelypaea is a poorly studied genus of the Orobanchaceae, comprising two species of non-photosynthetic root holoparasites. In this study, we sequenced the plastid genome of Diphelypaea coccinea and compared it with other Orobanchaceae, to elucidate patterns of plastid genome evolution. In addition, we used plastid genome data to define the phylogenetic position of Diphelypaea spp.MethodsThe complete nucleotide sequence of the plastid genome of D. coccinea was obtained from total plant DNA, using pyrosequencing technology.ResultsThe D. coccinea plastome is only 66,616 bp in length, and is highly rearranged; however, it retains a quadripartite structure. It contains only four rRNA genes, 25 tRNA genes and 25 protein-coding genes, being one of the most highly reduced plastomes among the parasitic Orobanchaceae. All genes related to photosynthesis, including the ATP synthase genes, had been lost, whereas most housekeeping genes remain intact. The plastome contains two divergent, but probably intact clpP genes. Intron loss had occurred in some protein-coding and tRNA genes. Phylogenetic analysis yielded a fully resolved tree for the Orobanchaceae, with Diphelypaea being a sister group to Orobanche sect. Orobanche.

Sequestration of pyridine alkaloids anabasine and nicotine from Nicotiana (Solanaceae) by Orobanche ramosa (Orobanchaceae)

Plants of the root holoparasite Orobanche ramosa L. and four of its potential host species, Nicotiana glauca Graham, Nicotiana rustica L., Nicotiana sylvestris Speg. & S.Comes, and Nicotiana tabacum L., grown in the greenhouse in Kiel/Germany, were analyzed for their contents of pyridine alkaloids anabasine (1) and nicotine (2). All investigated samples contained both alkaloids in different amounts. The distribution of the alkaloids in the various plant organs of Nicotiana differed significantly between the species. The alkaloid contents of the Orobanche samples relative to the alkaloid contents of the roots of the respective host plants varied between 3.47 ± 1.08 and 28.8 ± 37.5%. Orobanche plants drain water and crucial nutrients from their hosts; also, some examples for the sequestration of specialized natural products have been reported. O. ramosa is not able to synthesize pyridine alkaloids anabasine (1) and nicotine (2) itself; therefore, the present study proves the sequestration of pyridine alkaloids by O. ramosa from the four investigated Nicotiana host species.

Sequential horizontal gene transfers from different hosts in a widespread Eurasian parasitic plant, Cynomorium coccineum.

Parasitic plants with large geographic ranges, and different hosts in parts of their range, may acquire horizontally transferred genes (HGTs), which might sometimes leave a footprint of gradual host and range expansion. Cynomorium coccineum, the only member of the Saxifragales family Cynomoriaceae, is a root holoparasite that occurs in water-stressed habitats from western China to the Canary Islands. It parasitizes at least 10 angiosperm families from different orders, some of them only in parts of its range. This parasite therefore offers an opportunity to trace HGTs as long as parasite-host pairs can be obtained and sequenced. By sequencing mitochondrial, plastid, and nuclear loci from parasite-host pairs from throughout the parasite's range and with prior information from completely assembled mitochondrial and plastid genomes, we detected 10 HGTs of five mitochondrial genes. The 10 HGTs appear to have occurred sequentially as C. coccineum expanded from East to West. Molecular-clock models yield Cynomorium stem ages between 66 and 156 Myr, with relaxed clocks converging on 66-67 Myr. Chinese Sapindales, probably Nitraria, were the first source of transferred genes, followed by Iranian and Mediterranean Caryophyllales. The most recently acquired gene appears to come from a Tamarix host in the Iberian Peninsula. Data on HGTs that have accumulated over the past 15 years, along with this discovery of multiple HGTs within a single widespread species, underline the need for more whole-genome data from parasite-host pairs to investigate whether and how transferred copies coexist with, or replace, native functional genes.

ABA signaling components in Phelipanche aegyptiaca

Obligate root holoparasite Phelipanche aegyptiaca is an agricultural pest, which infests its hosts and feeds on the sap, subsequently damaging crop yield and quality. Its notoriously viable seed bank may serve as an ideal pest control target. The phytohormone abscisic acid (ABA) was shown to regulate P. aegyptiaca seed dormancy following strigolactones germination stimulus. Transcription analysis of signaling components revealed five ABA receptors and two co-receptors (PP2C). Transcription of lower ABA-affinity subfamily III receptors was absent in all tested stages of P. aegyptiaca development and parasitism stages. P. aegyptiaca ABA receptors interacted with the PP2Cs, and inhibited their activity in an ABA-dependent manner. Moreover, sequence analysis revealed multiple alleles in two P. aegyptiaca ABA receptors, with many non-synonymous mutations. Functional analysis of selected receptor alleles identified a variant with substantially decreased inhibitory effect of PP2Cs activity in-vitro. These results provide evidence that P. aegyptiaca is capable of biochemically perceiving ABA. In light of the possible involvement of ABA in parasitic activities, the discovery of active ABA receptors and PP2Cs could provide a new biochemical target for the agricultural management of P. aegyptiaca. Furthermore, the potential genetic loss of subfamily III receptors in this species, could position P. aegyptiaca as a valuable model in the ABA perception research field.

Identification of seeds of Phelipanche ramosa, Phelipanche mutelii and Orobanche cumana in the soils from different agricultural regions in Bulgaria by molecular markers

Broomrapes are root holoparasites from Orobanchaceae family parasitizing other flowering plants. Several of the most aggressive broomrape species are widely spread in Bulgaria often causing serious yield losses of important crops. It is important to be able to detect the presence of broomrape seeds in the soil. In the present study, we combined a proven PCR-based assay for detection of broomrape seeds with methods to distinguish species based on nuclear ITS sequences to identify broomrape seeds isolated from soil samples and to study the population structure and the intraspecific variations within the three species. Fifty-six soil samples from 23 different regions in Bulgaria were studied. Based on molecular and bioinformatics analyses we found that 22 samples contained seeds of Orobanche cernua var. cumana and six samples, seeds of Phelipanche ramosa. Phylogenic and bioinformatics analyses surprisingly revealed that the isolated sequences from supposedly P. mutelii seeds diverge from those annotated in NCBI by other authors on 16 different nucleotide positions and formed two distant branches of the phylogenic tree. On the other hand, the isolated sequences were almost identical with P. rosmarina. Tajimas’ D-test revealed that O. cumana populations are currently stable. Regarding the Phelipanche representatives, based on the D-test we can hypothesize that P. mutelii/P. rosmarina populations are in a period of active expansion, while P. ramosa populations are contracting. All isolated sequences were deposited in NCBI Genbank database.

PacBio-Based Mitochondrial Genome Assembly of Leucaena trichandra (Leguminosae) and an Intrageneric Assessment of Mitochondrial RNA Editing.

Reconstructions of vascular plant mitochondrial genomes (mt-genomes) are notoriously complicated by rampant recombination that has resulted in comparatively few plant mt-genomes being available. The dearth of plant mitochondrial resources has limited our understanding of mt-genome structural diversity, complex patterns of RNA editing, and the origins of novel mt-genome elements. Here, we use an efficient long read (PacBio) iterative assembly pipeline to generate mt-genome assemblies for Leucaena trichandra (Leguminosae: Caesalpinioideae: mimosoid clade), providing the first assessment of non-papilionoid legume mt-genome content and structure to date. The efficiency of the assembly approach facilitated the exploration of alternative structures that are common place among plant mitochondrial genomes. A compact version (729 kbp) of the recovered assemblies was used to investigate sources of mt-genome size variation among legumes and mt-genome sequence similarity to the legume associated root holoparasite Lophophytum. The genome and an associated suite of transcriptome data from select species of Leucaena permitted an in-depth exploration of RNA editing in a diverse clade of closely related species that includes hybrid lineages. RNA editing in the allotetraploid, Leucaena leucocephala, is consistent with co-option of nearly equal maternal and paternal C-to-U edit components, generating novel combinations of RNA edited sites. A preliminary investigation of L. leucocephala C-to-U edit frequencies identified the potential for a hybrid to generate unique pools of alleles from parental variation through edit frequencies shared with one parental lineage, those intermediate between parents, and transgressive patterns.

<b>Root holoparasite <I>Balanophora polyandra</I> Griff. (Balanophoraceae) in eastern Himalaya (Sikkim, India): distribution, range, status and threats</b>

Balanophora J.R. Forster & G. Forster (Balanophoraceae) is a poorly studied genus of root holoparasite native to temperate and tropical regions of Asia and the Pacific. The occurrences of Balanophora polyandra Griff. were first reported within two protected areas in eastern Himalaya (Sikkim, India), namely, Khangchendzonga National Park and Pangolakha Wildlife Sanctuary. The study assessed the distribution range of B. polyandra in Sikkim using data collected from both field surveys and herbarium records, and discussed the threats faced by Balanophora populations in the region.