Faculty of Biotechnology and Subtropical Horticulture Research Institute, Jeju National University, Jeju 690-756, Korea.
Planta. 2012 Oct;236(4):1135-50. doi: 10.1007/s00425-012-1662-6. Epub 2012 May 29.
Phytochrome A (phyA) in higher plants is known to function as a far-red/shade light-sensing photoreceptor in suppressing shade avoidance responses (SARs) to shade stress. In this paper, the Avena PHYA gene was introduced into creeping bentgrass (Agrostis stolonifera L.) and zoysiagrass (Zoysia japonica Steud.) to improve turf quality by suppressing the SARs. In addition to wild-type PHYA, a hyperactive mutant gene (S599A-PHYA), in which a phosphorylation site involved in light-signal attenuation was removed, was also transformed into the turfgrasses. Phenotypic traits of the transgenic plants were compared to assess the suppression of SARs under a simulated shade condition and outdoor field conditions after three growth seasons. Under the shade condition, the S599A-PhyA transgenic creeping bentgrass plants showed shade avoidance-suppressing phenotypes with a 45 % shorter leaf lengths, 24 % shorter internode lengths, and twofold increases in chlorophyll concentrations when compared with control plants. Transgenic zoysiagrass plants overexpressing S599A-PHYA also showed shade-tolerant phenotypes under the shade condition with reductions in leaf length (15 %), internode length (30 %), leaf length/width ratio (19 %) and leaf area (22 %), as well as increases in chlorophyll contents (19 %) and runner lengths (30 %) compared to control plants. The phenotypes of transgenic zoysiagrass were also investigated in dense field habitats, and the transgenic turfgrass exhibited shade-tolerant phenotypes similar to those observed under laboratory shade conditions. Therefore, the present study suggests that the hyperactive phyA is effective for the development of shade-tolerant plants, and that the shade tolerance nature is sustained under field conditions.
高等植物中的光敏色素 A（phyA）作为远红光/遮荫光感受光受体，在抑制遮荫胁迫下的避荫反应（SAR）中起作用。在本研究中，将燕麦 PHYA 基因导入匍匐翦股颖（Agrostis stolonifera L.）和结缕草（Zoysia japonica Steud.）中，通过抑制 SAR 来提高草坪质量。除了野生型 PHYA 外，还转化了一个超活性突变基因（S599A-PHYA），该基因去除了一个参与光信号衰减的磷酸化位点。对转基因植物的表型特征进行了比较，以评估在模拟遮荫条件和三个生长季后的室外田间条件下 SAR 的抑制情况。在遮荫条件下，与对照植株相比，S599A-PhyA 转基因匍匐翦股颖植物表现出避荫抑制表型，叶片长度缩短 45%，节间长度缩短 24%，叶绿素浓度增加一倍。过表达 S599A-PHYA 的转基因结缕草植物在遮荫条件下也表现出耐荫表型，与对照植株相比，叶片长度减少 15%，节间长度减少 30%，叶片长度/宽度比减少 19%，叶片面积减少 22%，叶绿素含量增加 19%，匍匐茎长度增加 30%。还在密集的田间生境中对转基因结缕草的表型进行了研究，转基因草坪草表现出与在实验室遮荫条件下观察到的相似的耐荫表型。因此，本研究表明，超活性 phyA 可有效用于开发耐荫植物，并且在田间条件下保持耐荫性。
