Plant Stress Research Unit, United States Department of Agriculture, Agricultural Research Service, Route 3, Box 215, 79401, Lubbock, Texas, USA.
Photosynth Res. 1993 Feb;35(2):135-47. doi: 10.1007/BF00014744.
In polyploid plants the photosynthetic rate per cell is correlated with the amount of DNA per cell. The photosynthetic rate per unit leaf area is the product of the rate per cell times the number of photosynthetic cells per unit area. Therefore, the photosynthetic rate per unit leaf area will increase if there is a less than proportional increase in cell volume at higher ploidal levels, or if cell packing is altered to allow more cells per unit leaf area. In autopolyploids (Medicago sativa, C3 species, and Pennisetum americanum, C4 species) there is a doubling of photosynthesis per cell and of cell volume in the tetraploid compared to the diploid. However, there is a proportional decrease in number of cells per unit leaf area with this increase in ploidy such that the rate of photosynthesis per leaf area does not change. There is more diversity in the relationship between ploidal level (gene dosage) and photosynthetic rates per unit leaf area in allopolyploids. This is likely to reflect the effects of natural selection on leaf anatomy, and novel genetic interactions from contributed genomes which can occur with allopolyploidy. In allopolyploid wheat (C3 species) a higher cell volume per unit DNA at the higher ploidal level is negatively correlated with photosynthesis rate per unit leaf area. Although photosynthesis per cell increases with ploidy, photosynthesis per leaf area decreases, being lowest in the allohexaploid, cultivated bread wheat (Triticum aestivum). Alternatively, doubling of photosynthetic rate per cell with doubling of DNA, with apparent natural selection for decreased cell volume per unit DNA, results in higher rates of photosynthesis per leaf area in octaploid compared to tetraploid Panicum virgatum (C4) which may be a case of allopolyploidy. Similar responses probably occur in Festuca arundinacea. Therefore, in some systems anatomical factors affecting photosynthesis are also affected by ploidal level. It is important to evaluate that component as well as determining the effect on biochemical processes. Current information on polyploidy and photosynthesis in several species is discussed with respect to anatomy, biochemistry and bases for expressing photosynthetic rates.
在多倍体植物中，每个细胞的光合速率与每个细胞的 DNA 量相关。单位叶面积的光合速率是每个细胞的速率乘以单位面积的光合细胞数的乘积。因此，如果在较高的多倍体水平下细胞体积的增加不成比例，或者通过改变细胞排列方式以允许单位叶面积上有更多的细胞，那么单位叶面积的光合速率将会增加。在同源多倍体（紫花苜蓿、C3 物种和青狗尾草、C4 物种）中，与二倍体相比，四倍体中每个细胞的光合作用和细胞体积都增加了一倍。然而，随着多倍体的增加，单位叶面积的细胞数成比例减少，使得叶面积的光合速率不变。异源多倍体中，多倍体水平（基因剂量）与单位叶面积光合速率之间的关系存在更多的多样性。这可能反映了自然选择对叶片解剖结构的影响，以及异源多倍体中可能发生的来自贡献基因组的新的遗传相互作用。在异源多倍体小麦（C3 物种）中，较高的单位 DNA 细胞体积与单位叶面积的光合速率呈负相关。尽管细胞内的光合作用随多倍体的增加而增加，但单位叶面积的光合作用却减少，在异源六倍体、栽培的面包小麦（Triticum aestivum）中最低。或者，细胞内光合作用随 DNA 的加倍而加倍，而单位 DNA 细胞体积的自然选择似乎减少，导致八倍体比四倍体青狗尾草（C4）的单位叶面积的光合速率更高，这可能是异源多倍体的一个例子。在高羊茅中可能也存在类似的反应。因此，在某些系统中，影响光合作用的解剖学因素也受多倍体水平的影响。评估该组成部分以及确定其对生化过程的影响非常重要。本文讨论了几个物种的多倍体和光合作用与解剖学、生物化学和表达光合速率的基础有关的信息。
