Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
VIB Center for Plant Systems Biology, Technologiepark 927, 9052, Ghent, Belgium.
Plant Cell Environ. 2018 Feb;41(2):374-382. doi: 10.1111/pce.13099. Epub 2017 Dec 11.
Research in maize is often performed using inbred lines that can be readily transformed, such as B104. However, because the B104 line flowers late, the kernels do not always mature before the end of the growing season, hampering routine seed yield evaluations of biotech traits introduced in B104 at many geographical locations. Therefore, we generated five hybrids by crossing B104 with the early-flowering inbred lines CML91, F7, H99, Mo17, and W153R and showed in three consecutive years that the hybrid lines proved to be suitable to evaluate seed yield under field conditions in a temperate climate. By assessing the two main processes driving maize leaf growth, being rate of growth (leaf elongation rate or LER) and the duration of growth (leaf elongation duration or LED) in this panel of hybrids, we showed that leaf growth heterosis was mainly the result of increased LER and not or to a lesser extent of LED. Ectopic expression of the transgenes GA20-oxidase (GA20-OX) and PLASTOCHRON1 (PLA1), known to stimulate the LER and LED, respectively, in the hybrids showed that leaf length heterosis can be stimulated by increased LER, but not by LED, indicating that LER rather than LED is the target for enhancing leaf growth heterosis.
玉米研究通常使用易于转化的自交系进行，例如 B104。然而，由于 B104 品系开花较晚，因此在生长季节结束之前，玉米穗并不总是完全成熟，这阻碍了在许多地理位置对 B104 中引入的生物技术性状进行常规种子产量评估。因此，我们通过将 B104 与早开花自交系 CML91、F7、H99、Mo17 和 W153R 杂交生成了五个杂种，并在连续三年的时间里证明，杂种系在温带气候的田间条件下能够很好地评估种子产量。通过评估驱动玉米叶片生长的两个主要过程，即生长速率（叶片伸长率或 LER）和生长持续时间（叶片伸长持续时间或 LED），我们表明，叶片生长杂种优势主要是由于 LER 的增加，而不是或在较小程度上是由于 LED 的增加。在杂种中异位表达已知分别刺激 LER 和 LED 的转基因 GA20-氧化酶（GA20-OX）和 PLATOCYRON1（PLA1）表明，叶片长度杂种优势可以通过增加 LER 来刺激，但不能通过 LED 来刺激，这表明 LER 而不是 LED 是增强叶片生长杂种优势的目标。
