Gaziosmanpaşa University, Department of Bioengineering, Tokat, Turkey.
Department of Agriculture, Tokat, Turkey.
Plant Physiol Biochem. 2018 Jun;127:256-268. doi: 10.1016/j.plaphy.2018.03.034. Epub 2018 Mar 31.
Roots are the major interface between the plant and various stress factors in the soil environment. Alteration of root system architecture (RSA) (root length, spread, number and length of lateral roots) in response to environmental changes is known to be an important strategy for plant adaptation and productivity. In light of ongoing climate changes and global warming predictions, the breeding of drought-tolerant grapevine cultivars is becoming a crucial factor for developing a sustainable viticulture. Root-trait modeling of grapevine rootstock for drought stress scenarios, together with high-throughput phenotyping and genotyping techniques, may provide a valuable background for breeding studies in viticulture. Here, tree grafted grapevine rootstocks (110R, 5BB and 41B) having differential RSA regulations and drought tolerance were investigated to define their drought dependent root characteristics. Root area, root length, ramification and number of root tips reduced less in 110R grafted grapevines compared to 5BB and 41B grafted ones during drought treatment. Root relative water content as well as total carbohydrate and nitrogen content were found to be much higher in the roots of 110R than it was in the roots of other rootstocks under drought. Microarray-based root transcriptome profiling was also conducted on the roots of these rootstocks to identify their gene regulation network behind drought-dependent RSA alterations. Transcriptome analysis revealed totally 2795, 1196 and 1612 differentially expressed transcripts at the severe drought for the roots of 110R, 5BB and 41B, respectively. According to this transcriptomic data, effective root elongation and enlargement performance of 110R were suggested to depend on three transcriptomic regulations. First one is the drought-dependent induction in sugar and protein transporters genes (SWEET and NRT1/PTR) in the roots of 110R to facilitate carbohydrate and nitrogen accumulation. In the roots of the same rootstock, expression increase in osmolyte producer genes revealed another transcriptomic regulation enabling effective root osmotic adjustment under drought stress. The third mechanism was linked to root suberization with upregulation of transcripts functional in wax producing enzymes (Caffeic acid 3-O-methyltransferase, Eceriferum3, 3-ketoacyl-CoAsynthase). These three transcriptomic regulations were suggested to provide essential energy and water preservation to the roots of 110R for its effective RSA regulation under drought. This phenotypic and genotypic knowledge could be used to develop root-dependent drought tolerant grapevines in breeding programs and could facilitate elucidation of genetic regulations behind RSA alteration in other plants.
根系是植物与土壤环境中各种胁迫因子的主要界面。根系结构（根长、根幅、侧根数和侧根长度）的改变是植物适应和生产力的重要策略。鉴于正在发生的气候变化和全球变暖预测，培育耐旱葡萄品种对于发展可持续的葡萄栽培至关重要。葡萄砧木的根系特征建模，结合高通量表型和基因型技术，可为葡萄栽培的育种研究提供有价值的背景。在这里，研究了具有不同 RSA 调节和耐旱性的 110R、5BB 和 41B 三种砧木，以确定其对干旱的依赖型根系特征。与 5BB 和 41B 嫁接葡萄相比，110R 嫁接葡萄的根区面积、根长、分枝和根尖数量在干旱处理期间减少较少。在干旱条件下，110R 根系的根相对含水量、总碳水化合物和氮含量均明显高于其他砧木。还对这些砧木的根系进行了基于微阵列的根系转录组分析，以鉴定其与干旱相关的 RSA 改变背后的基因调控网络。转录组分析显示，在严重干旱条件下，110R、5BB 和 41B 的根分别有 2795、1196 和 1612 个差异表达的转录本。根据这些转录组数据，110R 有效根伸长和根幅扩大性能被认为取决于三个转录组调节。第一个是糖和蛋白转运基因（SWEET 和 NRT1/PTR）在 110R 根系中的干旱诱导，以促进碳水化合物和氮的积累。在同一砧木的根中，渗透调节剂产生基因的表达增加揭示了另一个转录组调节，使有效根在干旱胁迫下进行渗透调节。第三个机制与根栓化有关，与蜡质产生酶（咖啡酸 3-O-甲基转移酶、Eceriferum3、3-酮酰基辅酶 A 合酶）功能相关的转录本上调。这三个转录组调节被认为为 110R 的根提供了必要的能量和水保存，以在干旱条件下进行有效的 RSA 调节。这种表型和基因型知识可用于在育种计划中开发依赖根系的耐旱葡萄品种，并有助于阐明其他植物中 RSA 改变的遗传调节。
