Dodder (Cuscuta spp.), with specific reference to Cuscuta chinensis, constitutes a globally significant parasitic plant genus characterized by its broad host range encompassing diverse botanical families including Fabaceae (Lanini et al. 2005). While previous studies have documented parasitism on herbaceous legumes such as Medicago sativa, this report provides the first confirmed evidence of C. chinensis parasitizing the arborescent legume Erythrina crista-galli, a species of considerable horticultural importance in subtropical urban landscapes (Farag et al. 2016). In June 2023, extensive infestations of C. chinensis were observed on twelve mature E. crista-galli specimens in Xishan Park, Kunming, Yunnan (102°42'95" N, 25°07'90" E elevation 1912 m). E. crista-galli ranging from 3.5 to 5.2 m in height with stem diameters of 30-45 cm at breast height, exhibited dense colonization of the parasite primarily localized at branch collars (68±3.2% of attachments, n=10) and bark fissures. Visible symptoms included pronounced interveinal chlorosis initiating from lower canopy leaves, with spectrophotometric analysis revealing mean CIELab values of L82, a-9.3, b32.1 in symptomatic foliage compared to L36, a-14.2, b9.7 in healthy controls. Advanced infections featured circumferential stem constriction (3.2-8.7 mm width reduction) and premature defoliation reaching 74.3±5.6% in parasitized trees versus 8.2±1.9% in unaffected individuals. Histological examination confirmed haustorial penetration extending 2.7-3.1 mm into xylem tissues, a notable deviation from typical phloem-limited colonization observed in herbaceous hosts. Quantitative ecological assessment was conducted across twenty systematically placed 1-m² quadrats within the 2-hectare infection zone. Field investigation confirmed exclusive C. chinensis restriction to E. crista-galli hosts (n=12) among 17 co-occurring woody species in Kunming (including Machilus yunnanensis (n=5), and Nandina domestica (n=7) with zero infections), suggesting host-specific susceptibility mechanisms in E. crista-galli. Spatial analysis indicated 87.6% of infestations occurred on branches with southern exposure, suggesting phototropic mediation of host selection. Molecular confirmation was attained through extraction of total DNA from mature stems using g the CTAB method (Doyle, J, et al. 1991), followed by whole-plastome sequencing via Illumina NovaSeq (2×150 bp, 120X coverage). The complete chloroplast genome (86,972 bp; GenBank accession PP796631) exhibited 99.95% identity with the C. chinensis reference sequence (MH780079), with genetic divergence quantified at 0.00015 substitutions per site (Qu et al. 2019). Phylogenetic reconstruction using maximum parsimony analysis of concatenated rbcL and matK sequences placed all isolates within a monophyletic clade exhibiting 100% bootstrap support with authenticated C. chinensis accessions. The absence of nonsynonymous mutations in protein-coding genes provided strong molecular corroboration of species identity. This novel host-parasite association exhibits several unconventional biological features. Unlike typical annual dodder life cycles, the parasite maintained photosynthetic activity when E. crista-galli entered its winter deciduous phase, suggesting partial autotrophic capacity. These findings demonstrate significant physiological strain beyond conventional host responses to Cuscuta parasitism. Herbarium voucher specimens documenting this interaction (C. chinensis on E. crista-galli) have been deposited in the repository of the College of Horticulture and Landscape, Yunnan Agricultural University under accession number 202311071EC. To the best of our knowledge, this constitutes the first global report of C. chinensis parasitizing any Erythrina species, expanding the known host range of this parasitic weed to include arborescent Fabaceae. Implement urgent mechanical removal pre-August seed maturation and localized 2.5% v/v glyphosate applications. Prioritize May-June phenological monitoring in co-occurrence zones.
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