# Genome of octoploid plant maca (Lepidium meyenii) illuminates genomic basis for high altitude adaptation in the central Andes

## TL;DR

The genome of maca, an Andean plant, reveals how it adapted to high altitudes through genetic changes.

## Contribution

The study provides the first high-quality genome assembly of octoploid maca and identifies genome duplications linked to high-altitude adaptation.

## Key findings

- Maca experienced two whole-genome duplications around 6.7 million years ago.
- Gene expansions related to stress response and metabolism are associated with high-altitude adaptation.
- Duplicated genes like MYB59, GDPD5, and HDA9 show signs of positive selection and morphological adaptation.

## Abstract

Maca (Lepidium meyenii Walp, 2n = 8× = 64) of Brassicaceae family is an Andean economic plant cultivated on the 4000-4500 meters central sierra in Peru. Considering the rapid uplift of central Andes occurred 5 to 10 million years ago (Mya), an evolutionary question arises on how plants like maca acquire high altitude adaptation within short geological period. Here, we report the high-quality genome assembly of maca, in which two close-spaced maca-specific whole genome duplications (WGDs, ∼ 6.7 Mya) were identified. Comparative genomics between maca and close-related Brassicaceae species revealed expansions of maca genes and gene families involved in abiotic stress response, hormone signaling pathway and secondary metabolite biosynthesis via WGDs. Retention and subsequent evolution of many duplicated genes may account for the morphological and physiological changes (i.e. small leaf shape and loss of vernalization) in maca for high altitude environment. Additionally, some duplicated maca genes under positive selection were identified with functions in morphological adaptation (i.e. MYB59) and development (i.e. GDPD5 and HDA9). Collectively, the octoploid maca genome sheds light on the important roles of WGDs in plant high altitude adaptation in the Andes.