The Fullest Map Yet of What the Red Bush's Genes Are Doing
University of the Western Cape researchers used long-read sequencing to build the most complete picture yet of which genes rooibos switches on, a step toward breeding bushes that can take a hotter, drier veld.
Two researchers at the University of the Western Cape have built the most complete map yet of which genes the red bush actually switches on, and the Ministry is glad to see it, because a plant this well studied in the cup has been surprisingly hard to read in the lab.
Tanweer Beckett and Uljana Hesse, of the university's Department of Biotechnology and its Institute for Microbial Biotechnology and Metagenomics in Bellville, published the work in the journal Plants on May 29. They ran leaf and root tissue of rooibos, Aspalathus linearis, through long-read sequencing, a newer method that reads long stretches of genetic material in one pass rather than stitching the picture together from short fragments.
The reading was deep. From 53.6 million reads, the team assembled 169,122 transcripts, the working copies a cell makes when it puts a gene to use, and predicted 95,054 proteins, about 80 percent of them full-length. Only 67 percent of those proteins had turned up in an earlier study built from short-read sequencing, which means the long reads caught close to a third more, many of them from the biosynthesis pathways that a breeder cares about. The leaf transcripts leaned toward photosynthesis and carbon fixation; the root transcripts toward root growth and the making of secondary compounds.
The point of all this is not a health headline. It is a toolkit. The authors say the map should help identify molecular markers for stress response, the genetic signposts that let a breeder pick out a hardier seedling early instead of waiting years to see how it copes. That matters because rooibos grows in only one place, the Cederberg, has almost never been irrigated, and faces a climate that is trending hotter and drier. A bush that can hold its yield through a bad season is worth a great deal, and finding one faster starts with knowing which genes are doing the work.
The Ministry's standing line does not move for a gene map any more than for a lab dish. Rooibos is caffeine-free and carries aspalathin, its signature antioxidant, and that much is settled. What this adds is quieter and, in its way, more lasting: a clearer picture of the plant itself, drawn in the country where it grows.
Sources: Beckett T, Hesse U, "Transcriptome Profiling of Leaves and Roots from Rooibos (Aspalathus linearis) Using Oxford Nanopore Sequencing," Plants, vol. 15, no. 11, article 1679 (29 May 2026), DOI: 10.3390/plants15111679.