Overexpression of AtBBX29 Improves Drought Tolerance by Maintaining Photosynthesis and Enhancing the Antioxidant and Osm
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ORIGINAL ARTICLE
Overexpression of AtBBX29 Improves Drought Tolerance by Maintaining Photosynthesis and Enhancing the Antioxidant and Osmolyte Capacity of Sugarcane Plants Nelisa Mbambalala 1 & Sanjib K. Panda 2 & Christell van der Vyver 1 Received: 8 April 2020 / Accepted: 6 November 2020 # The Author(s) 2020
Abstract B-box proteins have emerged as prominent mechanisms for controlling growth and developmental processes and in some instances responses to biotic and abiotic stresses in plants. These proteins mediate transcriptional regulations and protein– protein interactions in cellular signalling processes. B-box proteins thereby play an important role in coordinating physiological and biochemical pathway flux and are therefore ideal targets for controlling stress responses in plants. In this study, the overexpression of an Arabidopsis thaliana B-box gene (BBX29) in sugarcane (Saccharum spp. hybrid) has led to enhanced drought tolerance and delayed senescence under water-deficit conditions when compared to the wild-type plants. Transgenic plants maintained a higher relative water content and better protected its photosynthetic machinery. These plants accumulated more proline and displayed enhanced enzymatic antioxidant activity under drought conditions. Overexpression of AtBBX29 further alleviated the build-up of reactive oxygen species and curtailed oxidative damage, resulting in transgenic plants with improved health and higher survival rates during dehydration. Our results suggested that the AtBBX29 gene influenced an array of physiological and biochemical mechanisms in sugarcane to the advantage of the crop and might be a target to genetically engineer drought tolerance into sugarcane. This is the first report to elucidate B-box protein functionality in a polyploid crop such as sugarcane. Keywords Sugarcane . BBX . B-box proteins . Drought . Abiotic stress . Drought tolerance . Transcription factors
Introduction Sugarcane (Saccharum spp. hybrid) is one of the most important crops in the world, grown mostly for its high sucrose content and as an important biomass source for biofuel production. Sugarcane is a very productive but high waterdemanding crop, and its growth and sugar content are Key Message • AtBBX29 overexpression impart drought tolerance in sugarcane by limiting oxidative damage, enhancing antioxidant scavenging activities, increasing osmotic adjustment substrates and maintaining stomatal conductance and the chlorophyll fluorescence rate. * Christell van der Vyver [email protected] 1
Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7601, South Africa
2
Department of Biochemistry, Central University of Rajasthan, Rajasthan 305817, India
restricted by drought (Inman-Bamber and Smith 2005). Global climate change is causing frequent and severe drought spells worldwide, which became especially prevalent over the past decade in regions such as southern Africa (Nhamo et al. 2019). Therefore, sustainable production through induced tolerance towards li
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