Repeated evolution of salt-tolerance in grasses

Area of Science:

• Evolutionary biology
• Plant science
• Agricultural science

Background:

• Increasing global salt-affected soils necessitate salt-tolerant crops.
• Few salt-tolerant cereal crops are commercially available despite breeding efforts.
• Naturally salt-tolerant grass species are abundant, posing a puzzle for breeding.

Purpose of the Study:

• Investigate the evolutionary lability of salt tolerance in the grass family (Poaceae).
• Understand why salt tolerance is common in nature but difficult to breed into crops.
• Utilize a biodiversity-based, phylogenetic approach to study salt tolerance evolution.

Main Methods:

• Analyzed the phylogenetic distribution of salt tolerance across 2684 grass species.
• Confirmed findings using a genus-level phylogeny of over 800 grass genera.
• Examined the evolutionary history and frequency of salt tolerance trait acquisition.

Main Results:

• Salt tolerance has evolved independently over 70 times in diverse grass lineages.
• The trait's evolution is not restricted to specific clades, indicating broad potential.
• Despite frequent evolution, salt tolerance seldom results in large, distinct clades of tolerant species.

Conclusions:

• Salt tolerance is an evolutionarily labile trait in grasses, frequently appearing and disappearing.
• The difficulty in breeding salt-tolerant crops may stem from the trait's transient nature.
• Further research into the genetic and ecological factors governing salt tolerance stability is warranted.