Conrad U, Fiedler U
Institut für Pflanzengenetik und Kulturpflanzenforschung Gatersleben, Germany.
Plant Mol Biol. 1998 Sep;38(1-2):101-9.
Expression and stability of immunoglobulins in transgenic plants have been investigated and optimized by accumulation in different cellular compartments as cytosol, apoplastic space and endoplasmic reticulum (ER) as will be discussed in this review. In several cases described the highest accumulation of complete active antibodies was achieved by targeting into the apoplastic space. High-level expression of active recombinant single-chain Fv antibodies (scFv's) was obtained by retention of these proteins in the lumen of the endoplasmic reticulum. This has been shown for leaves and seeds of transgenic tobacco as well as for potato tubers. Transgenic tobacco seeds, potato tubers and tobacco leaves can facilitate stable storage of scFv's accumulated in the ER over an extended (seeds, tubers) or a short (leaves) period of time. The expression of specific scFv's in different plant species, plant organs and cellular compartments offers the possibility of blocking regulatory factors or pathogens specifically. Examples are scFv's expressed in the cytosol and the apoplastic space of transgenic plant cells modulating the infection process of plant viruses and a cytosolically expressed scFv that influenced the activity of phytochrome A protein. The immunomodulation approach has been shown to be also applicable for investigating the action of the phyto-hormone abscisic acid (ABA). High-level accumulation of specific anti-ABA scFv's in the ER of all leaf cells has been used to block the influence of ABA on the stomatal functions. Seed-specific expression of high amounts of anti-ABA-scFv's at a defined time of seed-development induced a developmental switch from seed ripening to vegetative growth. It has been demonstrated that ER retention is essential for the accumulation of sufficient scFv to bind high concentrations of ABA in the transgenic seeds.
免疫球蛋白在转基因植物中的表达和稳定性已通过在不同细胞区室（如细胞质、质外体空间和内质网（ER））中的积累进行了研究和优化，本综述将对此进行讨论。在所述的几个案例中，通过靶向质外体空间实现了完整活性抗体的最高积累。通过将这些蛋白质保留在内质网腔中获得了活性重组单链Fv抗体（scFv）的高水平表达。这已在转基因烟草的叶片和种子以及马铃薯块茎中得到证实。转基因烟草种子、马铃薯块茎和烟草叶片可以促进在内质网中积累的scFv在较长（种子、块茎）或较短（叶片）时间内的稳定储存。在不同植物物种、植物器官和细胞区室中表达特定的scFv提供了特异性阻断调节因子或病原体的可能性。例如，在转基因植物细胞的细胞质和质外体空间中表达的scFv调节植物病毒的感染过程，以及一种在细胞质中表达的scFv影响了光敏色素A蛋白的活性。免疫调节方法已被证明也适用于研究植物激素脱落酸（ABA）的作用。在所有叶细胞的内质网中特异性抗ABA scFv的高水平积累已被用于阻断ABA对气孔功能的影响。在种子发育的特定时间种子特异性表达大量抗ABA-scFv诱导了从种子成熟到营养生长的发育转变。已经证明内质网保留对于在转基因种子中积累足够的scFv以结合高浓度的ABA至关重要。
