Laboratório de Genoma Funcional, Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil.
Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany.
Ann Bot. 2019 Oct 29;124(4):691-700. doi: 10.1093/aob/mcz044.
Improving drought adaptation is more pressing for crops such as sugarcane, rice, wheat and maize, given the high dependence of these crops on irrigation. One option for enhancing adaptation to water limitation in plants is by transgenic approaches. An increasing number of genes that are associated with mechanisms used by plants to cope with water scarcity have been discovered. Genes encoding proteins with unknown functions comprise a relevant fraction of the genes that are modulated by drought. We characterized a gene in response to environmental stresses to gain insight into the unknown fraction of the sugarcane genome. Scdr2 (Sugarcane drought-responsive 2) encodes a small protein and shares highly conserved sequences within monocots, dicots, algae and fungi.
Plants overexpressing the Scdr2 sugarcane gene were examined in response to salinity and drought. Measurements of the gas exchange parameters, germination rate, water content, dry mass and oxidative damage were performed. Seeds as well as juvenile plants were used to explore the resilience level of the transgenic plants when compared with wild-type plants.
Overexpression of Scdr2 enhanced germination rates in tobacco seeds under drought and salinity conditions. Juvenile transgenic plants overexpressing Scdr2 and subjected to drought and salinity stresses showed higher photosynthesis levels, internal CO2 concentration and stomatal conductance, reduced accumulation of hydrogen peroxide in the leaves, no penalty for photosystem II and faster recovery after submission to both stress conditions. Respiration was not strongly affected by both stresses in the Scdr2 transgenic plants, whereas wild-type plants exhibited increased respiration rates.
Scdr2 is involved in the response mechanism to abiotic stresses. Higher levels of Scdr2 enhanced resilience to salinity and drought, and this protection correlated with reduced oxidative damage. Scdr2 confers, at the physiological level, advantages to climate limitations. Therefore, Scdr2 is a potential target for improving sugarcane resilience to abiotic stress.
由于这些作物高度依赖灌溉，因此提高甘蔗、水稻、小麦和玉米等作物的抗旱能力更为紧迫。增强植物对水分限制适应的一种选择是通过转基因方法。越来越多与植物应对缺水机制相关的基因已经被发现。编码具有未知功能蛋白质的基因构成了受干旱调控的基因的一个相关部分。我们对一个响应环境胁迫的基因进行了表征，以深入了解甘蔗基因组的未知部分。Scdr2（甘蔗干旱响应 2）编码一个小蛋白，在单子叶植物、双子叶植物、藻类和真菌中具有高度保守的序列。
对过表达 Scdr2 基因的植物进行了盐度和干旱胁迫响应的研究。测量了气体交换参数、发芽率、含水量、干重和氧化损伤。利用种子和幼株研究了转基因植物与野生型植物相比的恢复能力水平。
过表达 Scdr2 可提高烟草种子在干旱和盐胁迫下的发芽率。过表达 Scdr2 的转基因幼株在受到干旱和盐胁迫时表现出更高的光合作用水平、内部 CO2 浓度和气孔导度，减少叶片中过氧化氢的积累，对光系统 II 没有影响，在受到两种胁迫后恢复更快。两种胁迫对 Scdr2 转基因植物的呼吸作用没有强烈影响，而野生型植物的呼吸作用增加。
Scdr2 参与了非生物胁迫的响应机制。较高水平的 Scdr2 增强了对盐度和干旱的恢复能力，这种保护与减少氧化损伤有关。Scdr2 在生理水平上赋予了对气候限制的优势。因此，Scdr2 是提高甘蔗对非生物胁迫恢复能力的潜在目标。
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