Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720-3102, USA.
Biotechnology Division, Altria Client Services, Richmond, VA, 23219, USA.
Planta. 2018 Jul;248(1):139-154. doi: 10.1007/s00425-018-2889-7. Epub 2018 Apr 6.
Downregulation in the expression of the signal recognition particle 43 (SRP43) gene in tobacco conferred a truncated photosynthetic light-harvesting antenna (TLA property), and resulted in plants with a greater leaf-to-stem ratio, improved photosynthetic productivity and canopy biomass accumulation under high-density cultivation conditions. Evolution of sizable arrays of light-harvesting antennae in all photosynthetic systems confers a survival advantage for the organism in the wild, where sunlight is often the growth-limiting factor. In crop monocultures, however, this property is strongly counterproductive, when growth takes place under direct and excess sunlight. The large arrays of light-harvesting antennae in crop plants cause the surface of the canopies to over-absorb solar irradiance, far in excess of what is needed to saturate photosynthesis and forcing them to engage in wasteful dissipation of the excess energy. Evidence in this work showed that downregulation by RNA-interference approaches of the Nicotiana tabacum signal recognition particle 43 (SRP43), a nuclear gene encoding a chloroplast-localized component of the photosynthetic light-harvesting assembly pathway, caused a decrease in the light-harvesting antenna size of the photosystems, a corresponding increase in the photosynthetic productivity of chlorophyll in the leaves, and improved tobacco plant canopy biomass accumulation under high-density cultivation conditions. Importantly, the resulting TLA transgenic plants had a substantially greater leaf-to-stem biomass ratio, compared to those of the wild type, grown under identical agronomic conditions. The results are discussed in terms of the potential benefit that could accrue to agriculture upon application of the TLA-technology to crop plants, entailing higher density planting with plants having a greater biomass and leaf-to-stem ratio, translating into greater crop yields per plant with canopies in a novel agronomic configuration.
下调烟草信号识别颗粒 43（SRP43）基因的表达赋予了截短的光合光捕获天线（TLA 特性），从而导致植物具有更大的叶茎比、在高密度种植条件下提高了光合生产力和冠层生物量积累。在所有光合系统中，大量光捕获天线的进化赋予了生物体在野外的生存优势，在野外阳光通常是生长的限制因素。然而，在作物单作中，当在直射和过量阳光下生长时，这种特性是非常适得其反的。作物中大量的光捕获天线会导致冠层表面过度吸收太阳辐射能，远远超过饱和光合作用所需的量，并迫使它们浪费地耗散多余的能量。这项工作中的证据表明，通过 RNA 干扰方法下调烟草信号识别颗粒 43（SRP43），一种编码光合作用光捕获组装途径中叶绿体定位成分的核基因，导致光系统的光捕获天线大小减小，相应地增加了叶片中叶绿素的光合生产力，并在高密度种植条件下提高了烟草植物冠层生物量积累。重要的是，与在相同农艺条件下生长的野生型相比，具有 TLA 特性的转基因植物的叶茎生物质比具有实质性增加。结果从潜在的农业效益方面进行了讨论，即将 TLA 技术应用于作物植物可以带来更高的种植密度，植物具有更大的生物量和叶茎比，从而在新型农艺配置下每株植物的作物产量更高。
