Correlation of drought resistance in grass pea (Lathyrus sativus) with reactive oxygen species scavenging and osmotic adjustment

Grass pea (Lathyrus sativus L.), a legume crop in arid and semi-arid areas, is widely acknowledged as highly drought tolerant. We report here an analysis of grass pea and garden pea seedlings stressed with 20% polyethylene glycol 6000 (PEG) for five days. While leaf margins of grass pea curled inward after PEG stress, leaves of pea failed to display this trait. PEG inhibited the growth of grass pea less than that of pea. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) accumulation increased in pea more than in grass pea. Greater accumulation of proline and soluble sugars alleviated osmotic stress injury to grass pea compared with pea. Moreover, PEG caused a significantly greater increase of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) activities in grass pea compared to pea. These enzymes showed obvious up-regulation at the transcriptional level in grass pea leaves. Together, these data suggest that the accumulation of osmoprotectants and the improvement of oxidation resistance resulted in the higher drought tolerance of grass pea compared to pea.