Researchers at the Hebrew University of Jerusalem have identified a control system that lets seeds germinate under salt stress, a finding that could help breeders develop crops for saline soils. Working with the model plant Arabidopsis thaliana, the team studied how a germinating seed keeps the potassium its cells need while stopping sodium from reaching toxic levels.

Calcium, they found, switches on a mechanism built on three proteins: CAMTA6, which responds to the calcium signal and regulates the others, PP2C49 and the transporter HKT1;1. The genes are active in different parts of the embryo — some in the seed leaves, others in the embryonic root — so the seedling manages salt differently in each developing tissue.

Germination is an extremely vulnerable stage, said Dr Shkolnik, who led the work, because salt can upset the mineral balance a young plant needs before it has even broken the soil surface; what the group is beginning to uncover is the control system behind that response.

To test the pathway the researchers applied sanguinarine, a natural compound from bloodroot that inhibits PP2C49. Under moderate salt stress germination rose from 76% to 92%; under severe salt it rose from 3% to 37%, and treated seeds held less sodium and more potassium. The effect was confined to germination, however, and did not protect seedlings once they had emerged.

The three proteins are probably part of a much larger salt-response network, the team said; mapping it could eventually point breeders to genes that improve germination and establishment in salt-affected land — a problem that grows with irrigation, sea-level rise and drought across the world's coastal and dryland farming.

Source: Seed World Europe