欧亚国际

来自欧洲的科学家，利用WIWAM植物表型成像系统发表了题为“Aspen growth is not limited by starch reserves”的文章，文章发表于知名期刊Current Biology。WIWAM植物表型成像系统由SMO公司与比利时根特大学联合开发，目前利用WIWAM系统发表的已经数十篇。 

热点

杨树在生长过程中采用被动淀粉储存机制

在良性条件下，碳同化不会限制白杨树的生长

在白杨树中，芽的形成和芽快速生长或其时期不需要淀粉

总结

所有光合生物都将CO2同化与生长和碳储存进行平衡。需求超过同化时，储存的碳用于夜间生长。从机理上理解树木储存和生长之间的碳分配对于生物学研究和估计陆地光合作用吸收人为二氧化碳排放的潜力非常重要。1,2淀粉是植物3,4的主要碳储量。为了研究淀粉在树木生长过程中的碳储存机制和作用，我们使用CRISPR-Cas9介导的两个磷酸葡萄糖变位酶（PGM）基因编辑生成并表征了低淀粉杂交杨（山杨×山杨）树木，这两个基因编码淀粉生物合成所必需的质体PGM亚型。我们证明，即使在短时间内，淀粉缺乏也不会减少树木的生长，这表明淀粉不是白杨昼夜生长期间的关键碳储量。在一定的辐照度水平下，与野生型相比，低淀粉树吸收CO2减少可达30%，但这并没有减少生长或木材密度。这意味着在良性生长条件下，杨的生长不受碳同化的限制。此外，低淀粉树的芽变和芽加速生长时间没有改变，这意味着淀粉储量对季节性生长休眠周期并不关键。这些发现与一年生拟南芥被动淀粉储存机制一致，并表明杨吸收二氧化碳的能力受到库组织生长速率的限制。

关键字

杨树，淀粉，磷酸葡萄糖变位酶，碳分配

Aspen growth is not limited by starch reserves

Highlights

Aspen trees employ a passive starch-storage mechanism during growth

Carbon assimilation is not limiting growth of aspen trees under benign conditions

Starch is not required for bud set and bud flush or its timing in aspen trees

Summary

All photosynthetic organisms balance CO2 assimilation with growth and carbon storage. Stored carbon is used for growth at night and when demand exceeds assimilation. Gaining a mechanistic understanding of carbon partitioning between storage and growth in trees is important for biological studies and for estimating the potential of terrestrial photosynthesis to sequester anthropogenic CO2 emissions.1,2 Starch represents the main carbon storage in plants.3,4 To examine the carbon storage mechanism and role of starch during tree growth, we generated and characterized low-starch hybrid aspen (Populus tremula × tremuloides) trees using CRISPR-Cas9-mediated gene editing of two PHOSPHOGLUCOMUTASE (PGM) genes coding for plastidial PGM isoforms essential for starch biosesynthesis. We demonstrate that starch deficiency does not reduce tree growth even in short days, showing that starch is not a critical carbon reserve during diel growth of aspen. The low-starch trees assimilated up to ∼30% less CO2 compared to the wild type under a range of irradiance levels, but this did not reduce growth or wood density. This implies that aspen growth is not limited by carbon assimilation under benign growth conditions. Moreover, the timing of bud set and bud flush in the low-starch trees was not altered, implying that starch reserves are not critical for the seasonal growth-dormancy cycle. The findings are consistent with a passive starch storage mechanism that contrasts with the annual Arabidopsis and indicate that the capacity of the aspen to absorb CO2 is limited by the rate of sink tissue growth.