Overexpression of an NF-YB gene family member, EaNF-YB2, enhances drought tolerance in sugarcane (Saccharum Spp. Hybrid)

Background: Drought is one of main critical factors that limits sugarcane productivity and juice quality in tropical regions. The unprecedented changes in climate such as monsoon failure, increase in temperature and other factors warrant the need for development of stress tolerant cultivars to sustain sugar production. Plant Nuclear factor (NF-Y) is one of the major classes of transcription factors that have a major role in plant development and abiotic stress response. In our previous studies, we found that under drought conditions, the nuclear factor NF-YB2 was highly expressed in Erianthus arundinaceus, an abiotic stress tolerant wild genus of Saccharum species. In this study, the coding sequence of NF-YB2 gene was isolated from Erianthus arundinaceus and overexpressed in sugarcane to develop drought tolerant lines. RESULTS : EaNF-YB2 overexpressing sugarcane (OE) lines had higher relative water content, chlorophyll content and photosynthetic efficiency compared to non-transgenic (NT) control. In addition, overexpressing lines had higher activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR), and higher proline content, lower malondialdehyde (MDA) and peroxide (H₂O₂) contents. The expression studies revealed that EaNF-YB2 expression was significantly higher in OE lines than NT control under drought stress. The OE lines had an elevated expression of abiotic stress responsive genes such as BRICK, HSP 70, DREB2, EDH45, and LEA3. The morphological analysis revealed that OE lines exhibited less wilting than NT under drought conditions.

Conclusion: This study provides insights into the role of the EaNF-YB2 gene in drought tolerance in sugarcane. Based on the findings of this study, the EaNF-YB2 gene can be potentially exploited to produce drought tolerant sugarcane cultivars to sustain sugarcane production under water deficit conditions.