Coleman J S, Schneider K M
Department of Biology, Syracuse University, 130 College Place, 13244, Syracuse, NY, USA.
Oecologia. 1996 May;106(3):277-283. doi: 10.1007/BF00334555.
It has been suggested that abscisic acid (ABA) regulates a centralized response of plants to low soil resource availability that is characterized by decreased shoot growth relative to root growth, decreased photosynthesis and stomatal conductance, and decreased plant growth rate. The hypothesis was tested that an ABA-deficient mutant of tomato (flacca; flc) would not exhibit the same pattern of down-regulation of photosynthesis, conductance, leaf area and growth, as well as increased root/shoot partitioning, as its near isogenic wild-type in response to nitrogen or water deficiency, or at least not exhibit these responses to the same degree. Plants were grown from seed in acid-washed sand and exposed to control, nutrient stress, or water stress treatments. Additionally, exogenous ABA was sprayed onto the leaves of a separate group of flc individuals in each treatment. Growth analysis, based on data from frequent harvests of a few individuals, was used to assess the growth and partitioning responses of plants, and gas exchange characteristics were measured on plants throughout the experiment to examine the response of photosynthesis and stomatal conductance. Differences in growth, partitioning and gas exchange variables were found between flc and wild-type individuals, and both nutrient and water treatments caused significant reductions in relative growth rate (RGR) and changes in biomass partitioning. Only the nutrient treatment caused significant reductions in photosynthetic rates. However, flc and wild-type plants responded identically to nutrient and water stress for all but one of the variables measured. The exception was that flc showed a greater decrease in the relative change in leaf area per unit increase of plant biomass (an estimate of the dynamics of leaf area ratio) in response to nutrient stress-a result that is opposite to that predicted by the centralized stress response model. Furthermore, addition of exogenous ABA to flc did not significantly alter any of the responses to nutrient and water stress that we examined. Although it was clear that ABA regulated short-term stomatal responses, we found no evidence to support a pivotal role for ABA, at least absolute amounts of ABA, in regulating a centralized whole-plant response to low soil resource availability.
有人提出，脱落酸（ABA）调节植物对土壤资源低可用性的集中响应，其特征是地上部生长相对于地下部生长减少、光合作用和气孔导度降低以及植物生长速率下降。有人检验了这样一个假设：番茄的ABA缺陷型突变体（flacca；flc）在响应氮或水缺乏时，不会表现出与其近等基因野生型相同的光合作用、导度、叶面积和生长下调模式，以及根/冠比增加的模式，或者至少不会在相同程度上表现出这些响应。将种子种植在酸洗过的沙子中，使植物生长，并对其进行对照、养分胁迫或水分胁迫处理。此外，在每种处理中，将外源ABA喷洒到另一组flc个体的叶片上。基于对少数个体频繁收获的数据进行生长分析，以评估植物的生长和分配响应，并在整个实验过程中测量植物的气体交换特征，以检查光合作用和气孔导度的响应。发现flc和野生型个体在生长、分配和气体交换变量方面存在差异，养分和水分处理均导致相对生长速率（RGR）显著降低以及生物量分配发生变化。只有养分处理导致光合速率显著降低。然而，除了一个测量变量外，flc和野生型植物对养分和水分胁迫的响应相同。例外情况是，flc在响应养分胁迫时，单位植物生物量增加时叶面积的相对变化下降幅度更大（叶面积比动态的估计值）——这一结果与集中胁迫响应模型预测的结果相反。此外，向flc添加外源ABA并没有显著改变我们所研究的对养分和水分胁迫的任何响应。虽然很明显ABA调节短期气孔响应，但我们没有发现证据支持ABA在调节植物对土壤资源低可用性的集中全株响应中起关键作用，至少是ABA的绝对量起关键作用。
