Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, National Engineering Laboratory for Tree Breeding, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, Key Laboratory of Forest Trees and Ornamental Plants Biological Engineering of State Forestry Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China.
Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, 27695, USA.
Planta. 2019 Mar;249(3):635-646. doi: 10.1007/s00425-018-3029-0. Epub 2018 Oct 16.
Cell-size enlargement plays a pivotal role in increasing the leaf size of triploid poplar, and polyploidization could change leaf shape. ABP1 was highly expressed in triploid plants and positively related to cell size. In the plant kingdom, the leaf is the most important energy production organ, and polyploidy often exhibits a "Gigas" effect on leaf size, which benefits agriculture and forestry. However, little is known regarding the cellular and molecular mechanisms underlying the leaf size superiority of polyploid woody plants. In the present study, the leaf area and abaxial epidermal cells of diploid and triploid full-sib groups and their parents were measured at three different positions. We measured the expression of several genes related to cell division and cell expansion. The results showed that the leaf area of triploids was significantly larger than that of diploids, and the triploid group showed transgressive variation compared to their full-sib diploid group. Cell size but not cell number was the main reason for leaf size variation. Cell expansion was in accordance with leaf enlargement. In addition, the leaf shape changes in triploids primarily resulted from a significant decrease in the leaf ratio of length to -width. Auxin-binding protein 1 (ABP1) was highly expressed in triploids and positively related to leaf size. These results enhanced the current understanding that giant leaf is affected by polyploidy vigor. However, significant heterosis is not exhibited in diploid offspring. Overall, polyploid breeding is an effective strategy to enhance leaf size, and Populus, as an ideal material, plays an important role in studying the leaf morphological variations of polyploid woody plants.
细胞尺寸增大在三倍体杨树叶片增大中起关键作用，而多倍化可能会改变叶片形状。ABP1 在三倍体植物中高度表达，并与细胞大小呈正相关。在植物界中，叶片是最重要的能量生产器官，多倍体通常对叶片大小表现出“巨型”效应，这有利于农业和林业。然而，对于多倍体木本植物叶片大小优势的细胞和分子机制知之甚少。本研究在三个不同位置测量了二倍体和三倍体全同胞组及其亲本的叶片面积和下表皮细胞。我们测量了几个与细胞分裂和细胞扩展相关的基因的表达。结果表明，三倍体的叶片面积明显大于二倍体，三倍体群体与它们的全同胞二倍体群体相比表现出超越变化。细胞大小而不是细胞数量是叶片大小变化的主要原因。细胞扩展与叶片增大一致。此外，三倍体叶片形状的变化主要是由于叶片长度与宽度的比例显著降低。生长素结合蛋白 1（ABP1）在三倍体中高度表达，并与叶片大小呈正相关。这些结果增强了对巨型叶片受多倍体活力影响的认识。然而，在二倍体后代中并没有表现出显著的杂种优势。总体而言，多倍体育种是一种增强叶片大小的有效策略，杨树作为一种理想的材料，在研究多倍体木本植物叶片形态变化方面发挥着重要作用。
