# Genotype × Environment Effects in Three Wild Relatives of Sorghum From Australia

## TL;DR

Wild Sorghum species from Australia show greater genetic diversity and drought tolerance than domesticated sorghum, making them valuable for crop improvement.

## Contribution

The study reveals that wild Sorghum species exhibit minimal response to drought due to adaptation, with genotype effects outweighing environmental treatment effects.

## Key findings

- Wild Sorghum accessions showed minimal changes in biomass and chemical composition under drought conditions.
- Genotype effects were greater than treatment effects in wild Sorghum species.
- Wild Sorghum could provide novel traits to improve drought tolerance in domesticated sorghum.

## Abstract

Endemic wild Sorghum species are prevalent across northern Australia and could be useful for crop improvement; however, few studies have been done to quantify the phenotypic diversity of this tertiary gene pool. We aimed to assess the interactive effects of genotype and water availability in three wild Sorghum species native to northern Australia and compare these to domesticated sorghum (
Sorghum bicolor
). Two accessions of wild Sorghum plumosum,
Sorghum stipoideum
, and Sorghum timorense, sourced from more and less arid regions, were grown alongside a
S. bicolor
line under well‐watered or drought conditions for 4 weeks. We measured biomass, root:shoot ratio, chlorophyll a:b ratio, and concentrations of chlorophyll. The concentration of phenolics and cyanogenic glucosides were also measured to see if there were any differences in the concentration of specialized metabolites, as this is of particular importance for grazing. Low soil moisture (“drought”) significantly impacted the biomass, root:shoot ratio, and chemical composition of
S. bicolor
, but the effects on the wild accessions were minimal and mostly not significant. This is potentially a consequence of their adaptation to harsh conditions in northern Australia. In each of the wild study species, genotype effects (i.e., between accessions) were greater than treatment effects, indicating intraspecific diversity. Wild Sorghum is a potential source of novel traits that could be helpful in further enhancing the ability of
S. bicolor
to tolerate hot and dry conditions. Further research into traits conferring drought tolerance in Sorghum without compromising yield is needed.

Growth, dhurrin, and phenolic concentrations of three species of wild Sorghum native to Australia grown under well‐watered and water‐limited conditions varied more with genotype (i.e., among species and the aridity of the source populations) than experimental treatments.