Institute of Crop Science, Nutritional Crop Physiology, University of Hohenheim, Stuttgart, Germany.
J Exp Bot. 2018 Feb 23;69(5):1269-1279. doi: 10.1093/jxb/erx478.
Plants generally produce more biomass when all nutrients are available in sufficient amounts. In addition to environmental constraints, genetic and developmental factors, such as the transition from vegetative to reproductive growth, restrict maximal biomass yield. Here, we report the peculiar observation that a subset of Arabidopsis thaliana accessions produced larger shoot rosette diameters when grown in zinc (Zn)-deficient conditions, compared with Zn-sufficient conditions. This was associated with early flowering that restricted the leaf length under Zn sufficiency. Zinc deficiency repressed the expression of FLOWERING LOCUS T (FT), which encodes a major regulator of flowering. Repression or loss of FT increased the rosette diameter via a delay of the transition to flowering, a longer phase of leaf growth, and an increased leaf number. The transition to flowering reduced, but did not terminate, the proliferation of established leaves. The size of individual leaf mesophyll cells was not affected by Zn deficiency or by loss of FT, indicating that the larger rosette diameter was caused by maintained proliferation of vegetative tissue. As a consequence, early-flowering accessions under Zn deficiency grew to have larger rosette diameters due to a delay of flowering, which explains the unusual increase of vegetative biomass under nutrient deficiency.
当所有养分都以足够的数量存在时，植物通常会产生更多的生物量。除了环境限制外，遗传和发育因素，如从营养生长到生殖生长的转变，也限制了最大生物量的产生。在这里，我们报告了一个特殊的观察结果，即在缺锌条件下生长的拟南芥（Arabidopsis thaliana）部分品系的茎生叶直径比在锌充足条件下生长时更大。这与早期开花有关，在锌充足的情况下会限制叶片长度。缺锌会抑制开花的关键调节因子 FLOWERING LOCUS T（FT）的表达。FT 的抑制或缺失通过延迟开花、延长叶片生长阶段和增加叶片数量来增加冠层直径。向开花的转变减少了，但并没有终止已建立叶片的增殖。单个叶片叶肉细胞的大小不受锌缺乏或 FT 缺失的影响，这表明更大的冠层直径是由于营养组织的持续增殖所致。因此，由于开花的延迟，缺锌条件下的早花品系生长出更大的冠层直径，这解释了营养缺乏下植物生物量异常增加的原因。
