Transcriptome Profiling of a Common Mistletoe Species Parasitizing Four Typical Host Species in Urban Southwest China

Abstract

Comparing gene expression among parasitic plants infecting different host species can have significant implications for understanding host-parasite interactions. Taxillus nigrans is a common hemiparasitic species in Southwest China that parasitizes a variety of host species. However, a lack of nucleotide sequence data to date has hindered transcriptome-level research on T. nigrans. In this study, the transcriptomes of T. nigrans individuals parasitizing four typical host species (Broussonetia papyrifera [Bpap] a broad-leaved tree species; Cryptomeria fortunei [Cfor] a coniferous tree species; Cinnamomum septentrionale [Csep] an evergreen tree species; and Ginkgo biloba [Gbil] a deciduous-coniferous tree species) were sequenced, and the expression profiles and metabolic pathways compared among hosts. A total of 40.06 Gb of clean sequence data were generated in nine cDNA libraries. These were de novo assembled into 293,823 transcripts with an N50 value of 1790 bp. A large number of differentially expressed genes (DEGs) were identified when comparing T. nigrans individuals on different host species: Bpap vs. Cfor (713 DEGs), Bpap vs. Csep (1219), Bpap vs. Gbil (1514), Cfor vs. Csep (1639), Cfor vs. Gbil (1722), and Csep vs. Gbil (1723). Three hundred and eighty-one unigenes were common to all six pairwise comparisons; these were primarily associated with carbohydrate metabolism and energy metabolism, as determined in a KEGG enrichment analysis. Specific involvements included: the TCA cycle, biosynthesis of secondary metabolites, carbon metabolism, biosynthesis of amino acids and glyoxylate/dicarboxylate metabolism. A total of 251 unique unigenes were also identified, specific to either the Bpap vs. Cfor (249 unigenes) or Csep vs. Gbil (two unigenes) comparisons; partial unigenes were associated with the plasma membrane, response to endogenous stimuli, ion binding, and organic hydroxy compound metabolic processes. These results provide a foundation for further explorations of the detailed molecular mechanisms involved in plant parasitism.

Protein Profiling of Psittacanthus calyculatus during Mesquite Infection

“…In the seed free of exocarp, cell division is activated at the tip of the hypocotyl, producing a dome-shaped holdfast [ 57 ], which was displayed by a transversal section from stage T2 ( Figure 1 L). Stage T3 includes cotyledon aperture and from the lower side of the holdfast, a primary haustorium emerges and grows, which shows a predominant sideways growth ( Figure 1 M) that could be a response to contact with the host bark [ 64 ]. In stage T4, the parasitic endophyte becomes passively embedded within some host dermal tissues [ 65 , 66 ]: i) external bark, a protection layer insulator, prevents losing moisture and mechanical damage, ii) phloem, tissue that transport organic nutrients to the rest of the tree, iii) cambium, tissue that provides partially undifferentiated cells for generation of new bark, wood, and xylem tissue.…”

Mitigating the Mistletoe Menace: Biotechnological and Smart Management Approaches

“…Recently, Wahid’s work extensively used tools such as suppression subtractive hybridization (SSH) and next-generation sequencing (NGS) to report some 1279 genes in Ziarat junipers ( Juniperus excelsa ) in Balochistan, which might putatively confer resistance to the dwarf mistletoe Arceuthobium oxycedri [ 344 , 345 ]. Transcriptome profiling of Taxillus nigrans individuals on four different tree hosts revealed many host-specific and common pathways driving this mistletoe’s parasitism [ 346 ].…”