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Parasitic plants represent a significant challenge in global agriculture, with Broomrape (Orobanche/Phelipanche spp.) being a notable example of a holoparasitic species that targets the roots of host plants. This study employed comparative transcriptomics to investigate the mechanisms underlying the parasitism of P. aegyptiaca on melon, focusing on both resistant and susceptible interactions. The findings indicate that the critical phase of P. aegyptiaca parasitism occurs during the post-attachment stage. It is suggested that peptidases may play a role in the development of invasive cells, while cell wall-degrading enzymes (CWDEs) are likely involved in cell wall modification and degradation, and transferases, elicitors, and effectors may play a role in immune regulation. In this study, 25 tobacco rattle virus (TRV) recombinant vectors were successfully constructed and functionally validated using a host-induced gene silencing assay to explore the functions of candidate-secreted effector proteins. The results revealed that silencing Cluster-107894.0, Cluster-11592.0, and Cluster-12482.0 significantly decreased the parasitism rate of P. aegyptiaca on Nicotiana benthamiana. Notably, Cluster-107849.0 encodes a cellulase with hydrolase activity, Cluster-11592.0 encodes a periodic-dependent kinase inhibitor with phosphoprotein activity, and Cluster-12482.0 encodes a glucan 1,3-β-glucosidase with hydrolase activity. These findings potentially offer a novel theoretical framework and justification for understanding host–parasite plant interactions, and suggest new avenues for developing crop varieties resistant to parasitic infestation. [ABSTRACT FROM AUTHOR]

The efficient protoplast transient transformation system in plants is an important tool to study gene expression, metabolic pathways, and various mutagenic parameters, but it has not been established in Phelipanche aegyptiaca. As a root parasitic weed that endangers the growth of 29 species of plants in 12 families around the world, there is still no good control method for P. aegyptiaca. Even the parasitic mechanisms of P. aegyptiaca and the related genes regulating parasitism are not yet understood. In this study, by comparing the factors related to protoplast isolation and transfection, we developed the optimal protocol for protoplast isolation and transfection in Phelipanche aegyptiaca haustorium. The optimal protoplast yield and activity were 6.2 × 106 protoplasts/g fresh weight [FW] and 87.85%, respectively, by using 0.5 mol/L mannitol, enzyme concentrations of 2.5% cellulase R-10 and 0.8% Macerozyme R-10 at 24 °C for 4 h. At the same time, transfection efficiency of protoplasts was up to 78.49% when using 30 μg plasmid, 40% polyethylene glycol (PEG) concentration, 24 °C incubation temperature, and 20 min transfection time. This is the first efficient protoplasts' isolation and transient transformation system of Phelipanche aegyptiaca haustorium, laying a foundation for future studies on the gene function and mechanisms of haustorium formation in parasitic plants. [ABSTRACT FROM AUTHOR]

Phelipanche aegyptiaca Pers. is a holoparasitic plant that causes tremendous losses of agricultural crops worldwide. The initiation and development of the haustoria (special intrusive organs) is a key step in the growth of parasitic plants. The initiation of haustorium is largely dependent on haustorium-inducing factors (HIFs) secreted from host roots. Although HIFs of many semi-parasitic plants have been identified and reported, HIFs of the obligate parasitic plant P. aegyptiaca are largely unknown. This work demonstrated that the root exudates of the host plant Cucumis melo L. contain allelochemicals displaying haustorium-inducing activity on P. aegyptiaca germinating seeds, and there are significant differences in the induction effects of the resistant and susceptible C. melo cultivars of P. aegyptiaca (KR1326 and K1076). Ultra-performance liquid chromatography–mass spectrometry (UPLC-MS/MS) technology was used to identify and analyze the metabolites in root exudates of KR1326 and K1076. Cluster and PCA analyses showed significant differences between the metabolites in the KR1326 and K1076 root exudates. The determination of the haustorium induction effects of some metabolites screened from the differential metabolites indicated that scopoletin, quercetin, IAA, and DMBQ had relatively high haustorium induction activity. The results provide clues for finding HIFs of obligate parasitic plants and shed new light on the control of P. aegyptiaca by regulating haustorium development. [ABSTRACT FROM AUTHOR]

(D,F) Seed germination and haustorium induction rate of P. aegyptiaca induced by C. melo root exudates. Figure Graph: Figure 1 C. melo root exudates can induce the weed's germination and haustorium formation in P. aegyptiaca. (B) Representative image showing haustorium formation at the root tip of P. aegyptiaca seedlings after KR1326 root exudate treatment for 7 days. [Extracted from the article]

The electrocatalytic carbon dioxide reduction reaction (CO 2 RR) is a promising approach to achieving a sustainable carbon cycle. Recently, diatomic catalysts (DACs) have demonstrated advantages in the CO 2 RR due to their complex and flexible active sites. However, our understanding of how DACs break the scaling relationship remains insufficient. Here, we investigate the CO 2 RR of 465 kinds of graphene-based DACs (M1M2-N6@Gra) formed from 30 metal atoms through high-throughput density functional theory (DFT) calculations. We find that the intermediates *COOH, *CO, and *CHO have multiple adsorption states, with 11 structural flow directions from *CO to *CHO. Four of these structural flow directions have catalysts that can break the linear scale relationship. Based on the adsorption energy relationship between *COOH, *CHO and *CO, we propose the concepts of linear scaling, moderate breaking, and severe deviation regions, leading to the establishment of new descriptors that identify 14 catalysts with potential superior performance. Among them, ZnRu-N6@Gra and CrNi-N6@Gra can reduce CO 2 to CH 4 at a low limiting potential. We also discovered that DACs have independent bidirectional electron transfer channels during the adsorption and activation of CO 2 , which can significantly improve the flexibility and efficiency of regulating the electronic structure. Furthermore, through machine learning (ML) analysis, we identify electronegativity, atomic number, and d electron count as key determinants of catalyst stability. This work provides new insights into the understanding of the DAC catalytic mechanism, as well as the design and screening of catalysts., Competing Interests: The authors declare no competing financial interests., (This journal is © The Royal Society of Chemistry.)

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.

Coleus (Plectranthus scutellarioides [L.] R.Br.[syn.: Solenostemon scutellarioides]) is a perennial plant in the Lamiaceae family. It produces variegated leaves of various colors. It is commonly cultivated as an ornamental plant or grown in commercial greenhouses (Garibaldi et al. 2019). Phelipanche aegyptiaca Pers. is a dicotyledonous holoparasitic flowering plant that parasitizes more than 30 food crops (e.g., tomato, sunflower, and chickpea), ornamental crops, and others in different parts of the world, causing heavy economic losses (Nosratti et al. 2020). In 2016 and 2017, broomrape was observed parasitizing coleus in the greenhouse (86° 3' 36" E, 44° 18' 36" N, 500 m elevation) in Shihezi, Xinjiang, China (Supplementary Figure 1A-D). A single coleus plant could be parasitized by average 6-10 broomrape plants, and 20% of coleus plants were infested. The infection was confirmed by verifying the attachment of the broomrape to the coleus root. The inflorescences of the broomrape were normal and healthy and produced germinable seeds (germination rate: 80-90%). The morphological characteristics of the coleus are shown in Supplementary Figures 6 and 7. The main botanical features of the broomrape are as follows: (i) stem 20.65±7.07 cm tall, erect, branched, frail, rather hairy, bulbous at the base with secondary roots; (ii) inflorescence usually many-flowered, lax and cylindrical; (iii) bracts 6.87±0.93 mm long, ovate to lanceolate; (iv) calyx 1.09±0.09 cm long, shortly campanulate; (v) corolla 3.38±0.19 cm long, erect to suberect, white at the base, blue-purple in the upper part, sparsely glandular-villous; (vi) stamens 4, filaments inserted 5-6 mm from the base of the corolla, 1.26±0.11 cm long, anthers with villous; (vii) pistil 2.9±0.15 cm long, ovary glabrous, style with short glandular hairs, stigma bilobed, white (Supplementary Figure 2) (Teimoury et al. 2012; Piwowarczyk et al. 2019). For molecular identification, total genomic DNA was extracted from the flowers of the broomrape (found parasitizing coleus plants), and the ribosomal protein S2 (rps2) and ribosomal DNA internal transcribed spacer (ITS) region were amplified by PCR using the primer pairs rps2F/rps2R, ITS1/ITS4 (Table 1) (Park et al. 2007; Anderson et al. 2004). Two sequences with 580 bp (ITS) and 443 bp (rps2) were obtained (GenBank accession No. MW811482 and MW883573). BLAST analysis showed that the ITS sequence was most similar (identity 100%) to P. aegyptiaca (KC811171) and the rps2 sequence (identity 99%) also matched that of P. aegyptiaca (KC814957). Phylogenetic analysis of the ITS regions and rps2 genes showed that broomrape was fallen into P. aegyptiaca groups (Supplementary Figure 3). Morphological and molecular findings strongly support the conclusion that the broomrape on coleus was P. aegyptiaca. In order to verify that coleus was a host of P. aegyptiaca, coleus seedlings were collected and moved to 1.5-L pots containing a mixture of compost-vermiculite-sand (1:1:1 v:v:v) and seeds of P. aegyptiaca harvested from the host coleus (50 mg of P. aegyptiaca seeds per 1 kg of the substrate). Another three coleus seedlings were transplanted into pots of the same size containing the same mixture as above without P. aegyptiaca seeds. These served as controls. After 90 days of inoculation, the leaves of the infected hosts were lighter in color than those of uninfected hosts (Supplementary Figures 4A, 6). The roots of coleus and P. aegyptiaca were carefully washed with water, and an average of 3-4 emerged broomrape shoots and 50-60 underground attachments were observed on coleus roots (Supplementary Figure 4B). P. aegyptiaca can develop normally in the root of the coleus plant, from germination through attachment to host roots and development of tubercles (Supplementary Figure 5 A-E). Longitudinal and transverse sections of the parasite and host roots at the tubercle stage revealed that the endophytic tissues of P. aegyptiaca had reached and connected to the host vascular bundle (Supplementary Figure 5F-I), confirming the normal biological development and function of P. aegyptiaca haustoria. To the best of our knowledge, this is the first report of P. aegyptiaca parasitizing coleus in Xinjiang, China. Coleus is a very widely cultivated horticultural ornamental plant, and it grows in the same environments favored by P. aegyptiaca; so, the plant can aid the transmission of P. aegyptiaca to previously clear regions. It is necessary to improve the management of coleus in places where P. aegyptiaca is prevalent so as to reduce its spread. References: Garibaldi, A., et al. 2019. Plant Dis. 104:590. https://doi.org/10.1094/PDIS-07-19-1399-PDN Crossref, ISI, Google Scholar Nosratti, I., et al. 2020. 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