# Acacia koa seedling disease tolerance and vigor driven by breeding orchard size

## TL;DR

This paper shows how breeding Acacia koa trees in larger orchards improves their disease tolerance and growth, offering a model for improving other tree species.

## Contribution

The study demonstrates rapid genetic improvement in koa through breeding orchard size and selection methods.

## Key findings

- Large breeding orchards significantly enhance disease tolerance and vigor in Acacia koa seedlings.
- Simulation suggests selection methods can accelerate the improvement of koa germplasm.
- Koa domestication provides a model for efficient tree breeding in other species.

## Abstract

Acacia koa Gray (koa) is a Hawaiian endemic tree species that has a long history of use in the islands. In the late 20th century disease started impacting native koa stands, leading to the initiation of seed orchards that were founded from seeds collected across the islands. Large improvements in disease tolerance and vigor were achieved in very few cycles of selection despite the long temporal time of this perennial hardwood tree species. Initial selection on agronomic and domestication traits improved populations to the agricultural and natural ecosystem. Further, using simulation we identified how different methods of selection could be implemented to more rapidly make progress toward improved koa germplasm. Our evidence shows that domestication in Acacia koa provides a model for parametrization of crossing in the breeding cycle for rapid improvement of any tree species.