New Genome Assembly Sheds Light on Tropical Vine's Invasive Success

Merremia boisiana, a member of the Convolvulaceae family, a fast-growing vine native to tropical rainforests and known for its vibrant golden flowers and astonishing climbing ability, grows at speeds exceeding 12 cm per day, often overwhelming native vegetation and disrupting forest ecosystems. Despite its ecological importance and genetic proximity to economically vital crops like sweet potato (Ipomoea batatas), little was known about its genomic makeup until now.

A study (DOI:10.48130/tp-0025-0007) published in Tropical Plants on 24 March 2025 by Fei Chen and Wenquan Wang's team, Hainan University, marks a significant leap forward in Convolvulaceae research, providing a foundation for gene mining, comparative genomics, and breeding strategies.

To uncover the genomic basis underlying the rapid growth and ecological adaptability of Merremia boisiana, researchers conducted a comprehensive chromosome-level genome assembly using a combination of advanced sequencing technologies. The project began with flow cytometry, estimating the genome size at 523 Mb, followed by the generation of 68 Gb of Illumina paired-end reads and 59.5 Gb of Oxford Nanopore long reads, achieving over 130% genome coverage. Hi-C data totaling 141 Gb were utilized to scaffold the assembly, which resulted in 15 well-resolved chromosomes and a final genome size of 510 Mb, closely matching the initial estimate. Evaluation using BUSCO indicated a high completeness of 98.7%, with additional quality metrics such as an LAI score of 11.27 and a Merqury quality value of 33.2, confirming the genome's suitability as a reference. Subsequent annotation efforts, integrating de novo prediction, homology alignment, and transcriptome data, identified 37,389 protein-coding genes with a BUSCO completeness of 99.2%. Repeat sequence analysis revealed that 60.93% of the genome comprises repetitive elements, including 18.78% LTRs. Comparative genomic analyses across 62 species positioned M. boisiana as closely related to Ipomoea, with divergence occurring approximately 20 million years ago. Gene family analysis uncovered an expansion of 1,377 genes in M. boisiana, particularly those involved in hormone biosynthesis and stress response, which may underlie its invasive potential. Ancestral genome reconstruction suggested a whole-genome triplication event followed by chromosomal rearrangements that shaped the current 15-chromosome structure. These rearrangements likely contributed to the retention and diversification of key genes, especially those regulating hormone pathways. Indeed, the genome harbors a rich repertoire of genes involved in auxin, salicylic acid, ABA, and jasmonic acid biosynthesis, many of which exhibit root-specific expression, pointing to their role in enhanced root development, rapid growth, and ecological competitiveness in tropical environments.

This great genome assembly of Merremia boisiana uncovers the genetic engine behind one of the world's fastest-growing tropical vines. Its remarkable growth and resilience are underpinned by hormone biosynthesis genes and evolutionary genomic events-knowledge that not only decodes a rainforest enigma but also offers powerful tools for crop improvement and biodiversity conservation.