Phytochrome signalling in plant canopies: Testing its population-level implications with photoreceptor mutants of Arabidopsis
Phytochrome signalling in plant canopies: Testing its population-level implications with photoreceptor mutants of Arabidopsis
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DOI：
10.1046/j.1365-2435.1997.00108.x
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发表时间：
1997-08-01
影响因子：
5.2
通讯作者：
Scopel, AL
中科院分区：
文献类型：
--
作者：
Ballare, CL;Scopel, AL
1.许多信号机制负责触发植物对邻近植物的可塑性形态和生理反应。在这些机制中，光敏色素介导的分支和伸长的控制响应于红色：远红比（R：FR）的改变已被研究得相当详细。虽然光敏色素B在R：FR感知中的作用已经得到很好的确立，并且相邻光检测对竞争能力的影响正在受到关注，但关于植物-植物信号在冠层中的生态学，仍有几个重要问题有待解决。特别是，其他光感受器在邻居检测中的作用以及邻居检测对种群水平属性的影响，例如大小结构和生产力：密度关系的特征很差。在这里报道的实验中，我们解决了这些问题，使用野生型（WT）植物和光形态发生突变体的拟南芥，是专门缺乏光敏色素A，光敏色素B，所有光敏色素或蓝光感光隐花色素。从种植到结籽，植物在不同密度的单一栽培中生长（在300和2400株m（-2）之间）。相邻植物之间的充分竞争在地上和地下都是允许的。野生型植物响应拥挤与可预测的增加伸长生长和生产更陡峭的取向叶。在光敏色素A或隐花色素缺乏的突变体中观察到类似的反应。缺乏光敏色素B的突变体植物即使在低密度下生长也具有“伸长”表型，并且与其他基因型相比，对拥挤的形态反应显着降低。所有基因型具有功能光敏色素B有类似的生物量生产和水果生产，和水果生产单位面积是恒定的密度范围内使用。在中等密度下，缺光敏色素B植物的林分产量与野生型林冠一样高，但在低密度下显著降低了果实产量，更引人注目的是，在高密度下也是如此。相邻林分之间的大小不平等，以单株生殖产量的变异系数来衡量，在所有基因型中，随着密度的增加而增加，但缺光敏色素B的林分比野生型作物显著增加。我们的研究结果表明：（1）光敏色素B在相邻光检测中起着独特的作用，而其他光感受器在这方面似乎不那么重要;（2）在WT林分中，光敏色素-B-介导的相邻检测导致逆秩依赖的形态调整（即，在小植物中的更大的分数响应），其倾向于缓冲植物群体对大小结构的影响;（3）R：FR“盲”光敏色素B突变体群体的强大小结构导致高密度下林分繁殖力降低。
1. A number of signalling mechanisms are responsible for triggering plastic morphological and physiological responses of plants to the proximity of neighbours. Among these mechanisms, the phytochrome-mediated control of branching and elongation in response to alterations in red:far-red ratio (R:FR) has been investigated in considerable detail.2. While the role of phytochrome B in R:FR perception has been well established, and the consequences of neighbour photo-detection on competitive ability are receiving attention, several important issues remain to be addressed regarding the ecology of plant-plant signalling in canopies. In particular, the role of other photoreceptors in neighbour detection and the impact of neighbour detection on population-level attributes, such as size structure and productivity:density relationships are poorly characterized.3. In the experiments reported here we addressed these questions using wild-type (WT) plants and photomorphogenic mutants of Arabidopsis thaliana that are specifically deficient in phytochrome A, phytochrome B, all phytochromes or the blue-light photoreceptor cryptochrome. Plants were grown in monocultures of different densities (between similar to 300 and 2400 plants m(-2)) from planting to seed set. Full competition among neighbouring plants was allowed both above-and below-ground.4. WT plants responded to crowding with the predictable increase in elongation growth and by producing more steeply orientated leaves. Similar responses were observed in mutants deficient in phytochrome A or cryptochrome. Mutant plants lacking phytochrome B had an 'elongated' phenotype even when grown at low density and, in comparison with the other genotypes, showed markedly reduced morphological responses to crowding.5. All genotypes having functional phytochrome B had similar biomass production and fruit production, and fruit production per unit area was constant over the range of densities used. Stands of phytochrome-B-deficient plants were as productive as WT canopies at intermediate densities, but had significantly reduced fruit production at low and, more strikingly, also at high densities, Size inequality among neighbours, measured as the coefficient of variation of reproductive output per plant, increased with density in all genotypes, but significantly more in phytochrome-B-deficient stands than in WT crops.6. Our results suggest that: (1) phytochrome B plays a unique role in neighbour photodetection, while other photoreceptors appear to be less important in this respect; (2) in WT stands, phytochrome-B-mediated neighbour detection leads to inverse rank-dependent morphological adjustments (i.e. greater fractional response in the small plants), which tend to buffer the plant population against size structuring; (3) the strong size-structuring in populations of R:FR 'blind' phytochrome-B mutants results in reduced stand fecundity at high densities.