Rapid identification of drought tolerant sugarcane epimutants via in vitro chimera dissolution and near infrared screening ex vitro

Abstract

Drought is an important stress factor with increased severity due to climate change. Previous research characterised drought-tolerant sugarcane epimutants over several rounds of ex vitro screening on vegetatively derived survivors. In the present work, a quicker in vitro chimera dissolution over four stress rounds is reported in cultivar N41. Overall, epimutants were significantly taller (1.32–2.20 cm), had wider leaves (up to 0.40 cm) and thicker stems (0.26–0.37 cm) than the stressed control (S N41) with up to 0.92 cm height, 0.27 cm leaf width, and 0.18 cm stem diameter over the last three in vitro stress rounds. The Dry 8, Dry 5, Dry 2, Dry 3, and Dry 1 were identified as lines tolerant to osmotic and heat stress. When detached leaves were treated with polyethylene glycol for 7 days, Dry 8 and Dry 5 showed significantly higher green leaf areas of 90.02 and 80.29%, respectively, than S N41 with 60.23%. Following ex vitro drought selection, Dry 8 had a rapid growth rate (0.39 cm/day) compared with S N41 (0.23 cm/day). Based on near-infrared spectroscopy (NIRS) data, Dry 1, Dry 2, Dry 5, and Dry 8 were grouped with the non-stressed control (NS N41). The Dry 5 and Dry 8 epilines were persistently tolerant to osmotic, heat and drought stresses in pot-based bioassays and were identified as the best epilines in the study. These results suggest that stable epilines with drought tolerance potential can be obtained through in vitro screening methods and ex vitro NIR-based phenotyping, allowing a more rapid throughput of useful lines than in previous studies.