ABSTRACT

Plant growth is continuously modulated by endogenous and exogenous stimuli. By no means the only, but well described, signaling molecules produced in plants and distributed through the plant body to orchestrate efficient growth are photosynthates. Light is a potent exogenous stimulus that determines, first, the rate of photosynthesis, but also the rate of plant growth. Root meristem activity is reduced with direct illumination but enhanced with increased sugar levels. With reduced cotyledon illumination, the seedling increases hypocotyl elongation until adequate light exposure is again provided. If endogenous carbon sources are limited, this leads to a temporary inhibition of root growth. Experimental growth conditions include exogenous supplementation of sucrose or glucose in addition to culturing seedlings under light exposure in Petri dishes. We compared total root length and hypocotyl elongation of Arabidopsis thaliana wild type Col-0 in response to illumination status and carbon source in the growth medium. Overall, sucrose supplementation promoted hypocotyl and root length to a greater extent than glucose supplementation. Glucose promoted root length compared to non-supplemented seedlings especially when cotyledon illumination was greatly reduced.

摘要

植物生长不断受到内源和外源刺激的调节。在植物中产生并分布在植物体中以协调有效生长的信号分子绝不是唯一但描述得很好的光合产物。光是一种强有力的外源刺激，它首先决定了光合作用的速度，也决定了植物的生长速度。直接光照会降低根分生组织的活性，但会随着糖含量的增加而增强。随着子叶光照的减少，幼苗会增加下胚轴伸长，直到再次提供足够的光照。如果内源碳源有限，这会导致根系生长的暂时抑制。实验性生长条件包括外源补充蔗糖或葡萄糖，以及在培养皿中光照下培养幼苗。拟南芥野生型Col-0响应生长培养基中的光照状态和碳源。总体而言，补充蔗糖比补充葡萄糖更能促进下胚轴和根长。与未补充的幼苗相比，葡萄糖促进了根长，尤其是当子叶光照大大降低时。