Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa.
Department of Genetics, University of Stellenbosch, Stellenbosch, South Africa.
Plant Biol (Stuttg). 2023 Dec;25(7):1121-1141. doi: 10.1111/plb.13585. Epub 2023 Oct 19.
Sugarcane is an economically important crop plant across the globe as it is the primary source of sugar and biofuel. Its growth and development are greatly influenced by water availability; therefore, in periods of water scarcity, yields are severely compromised. Small Ubiquitin-Like Modifier (SUMO) proteases play an important role in stress responses by regulating the SUMO-related post-translational modification of proteins. In an attempt to enhance drought tolerance in sugarcane, this crop was genetically transformed with a cysteine protease (OVERLY TOLERANT TO SALT-1; OTS1) from Arabidopsis thaliana using particle bombardment. Transgenic plants were analysed in terms of photosynthetic capacity, oxidative damage, antioxidant accumulation and the SUMO-enrich protein profile was assessed. Sugarcane transformed with the AtOTS1 gene displayed enhanced drought tolerance and delayed leaf senescence under water deficit compared to the untransformed wild type (WT). The AtOTS1 transgenic plants maintained a high relative moisture content and higher photosynthesis rate when compared to the WT. In addition, when the transgene was expressed at high levels, the transformed plants were able to maintain higher stomatal conductance and chlorophyl content under moderate stress compared to the WT. Under severe water deficit stress, the transgenic plants accumulated less malondialdehyde and maintained membrane integrity. SUMOylation of total protein and protease activity was lower in the AtOTS1 transformed plants compared to the WT, with several SUMO-enriched proteins exclusively expressed in the transgenics when exposed to water deficit stress. SUMOylation of proteins likely influenced various mechanisms contributing to enhanced drought tolerance in sugarcane.
甘蔗是全球经济重要的作物之一，因为它是糖和生物燃料的主要来源。其生长和发育受水分可用性的影响很大；因此，在水资源匮乏时期，产量会严重受损。小泛素样修饰物（SUMO）蛋白酶通过调节蛋白质的 SUMO 相关翻译后修饰，在应激反应中发挥重要作用。为了提高甘蔗的耐旱性，本研究通过粒子轰击将拟南芥中的半胱氨酸蛋白酶（OVERLY TOLERANT TO SALT-1；OTS1）基因遗传转化到甘蔗中。对转基因植株的光合作用能力、氧化损伤、抗氧化剂积累以及 SUMO 富集蛋白谱进行了分析。与未转化的野生型（WT）相比，转入 AtOTS1 基因的甘蔗在水分亏缺下表现出增强的耐旱性和延迟的叶片衰老。与 WT 相比，AtOTS1 转基因植株在相对较高的水分含量和较高的光合作用率下保持了较高的水分含量。此外，当转基因表达水平较高时，与 WT 相比，转化植株在适度胁迫下能够维持较高的气孔导度和叶绿素含量。在严重水分亏缺胁迫下，转基因植株积累的丙二醛较少，保持膜的完整性。与 WT 相比，AtOTS1 转化植株的总蛋白 SUMO 化和蛋白酶活性较低，在暴露于水分亏缺胁迫时，几种 SUMO 富集蛋白仅在转基因植株中表达。蛋白质的 SUMO 化可能影响了增强甘蔗耐旱性的各种机制。
