Salt-tolerance mechanisms in quinoa: Is glycinebetaine the missing piece of the puzzle?
Enrique Olmos, B Jimenez-Perez, Inmaculada Román-García, Nieves Fernández‐García
Abstract
Salinization of arable land has been progressively increasing, which, along with the effects of climate change, poses a serious risk to food production. Quinoa is a halophyte species that grows and is productive in highly saline soils. This study addresses the mechanisms of response and adaptation to high salinity. We show that the differential distribution of sodium in plants depends on the variety, observing that varieties such as Pandela Rosada limit the passage transit of sodium to the aerial part of the plant, a mechanism that seems to be regulated by sodium transporters such as HKT1s or SOS1. Like other halophytes of the Amaranthaceae family, quinoa plants have salt glands (bladder cells), which have been reported to play an important role in salt tolerance. However, our study shows that the contribution of bladder glands to salt accumulation is rather low. The 1 H-NMR metabolome study of quinoa subjected to salt stress showed important modifications in the contents of amino acids, sugars, organic acids, and quaternary ammonium compounds (glycinebetaine). The compound with a higher presence was glycinebetaine, which makes up 6% of the leaf dry matter under saline conditions. Our findings suggest that glycinebetaine can act as an osmolyte and/or osmoprotectant, facilitating plant development under high saline ambient. • HKT1 and SOS transporters are involved in sodium partitioning in Pandela Rosada. • The total gland volume represents a low percentage of the total leaf volume (4–9%). • The contribution of bladder cells to salt accumulation is rather low in quinoa. • Glycinebetaine reaches up to 6% of the DW in salt treatment on quinoa leaves. • Glycinebetaine may contribute up to 67% of the osmotic adjustment in the cytoplasm.