SUPPRESSOR OF MAX2 1-LIKE 5 promotes secondary phloem formation during radial stem growth.
SUPPRESSOR OF MAX2 1-LIKE 5 promotes secondary phloem formation during radial stem growth.
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DOI：
10.1111/tpj.14670
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Eva-Sophie Wallner;Nina Tonn;Dongbo Shi;Virginie Jouannet;T. Greb
中科院分区：
文献类型：
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作者：
Eva-Sophie Wallner;Nina Tonn;Dongbo Shi;Virginie Jouannet;T. Greb
作为持续生长的先决条件，植物在胚后体内的不同位置产生维管组织。有趣的是，在茎和根轴的纵向和径向扩张过程中，维管组织的形成在解剖结构上是根本不同的。这就提出了这样一个问题：在整个植物发育过程中，维管组织形成的调控机制在何种程度上是相同的。在这里，我们表明，类似于纵向生长过程中初级韧皮部的形成，次生韧皮部形成层的形成依赖于Max21-like(SMXL)基因抑制因子的功能。特别是局部的SMXL5缺失导致次生韧皮部的缺失。此外，SMXL4活性的额外破坏增加了形成层区域的组织产量，而没有形成次生韧皮部。利用启动子报告系，我们观察到SMXL4和SMXL5活性与拟南芥茎中次生韧皮部形成的不同阶段有关。根据全基因组转录图谱和韧皮部相关标记的表达分析，我们得出结论：在smx14；smx15双突变体中，韧皮部形成的早期步骤受到损害，额外的形成层细胞未能建立与韧皮部相关的特征。我们的结果表明，决定初生和次生韧皮部形成的分子机制具有重要的性质，但与SMXL5在次生韧皮部形成中起主导作用的分子机制略有不同。
As a prerequisite for constant growth, plants produce vascular tissues at different sites within their postembryonic body. Interestingly, the formation of vascular tissues during longitudinal and radial expansion of shoot and root axes differs fundamentally with respect to its anatomical configuration. This raises the question to which level regulatory mechanisms of vascular tissue formation are shared throughout plant development. Here, we show that, similar to primary phloem formation during longitudinal growth, the cambium-based formation of secondary phloem depends on the function of SUPPRESSOR OF MAX2 1-LIKE (SMXL) genes. In particular, local SMXL5 deficiency results in the absence of secondary phloem. Moreover, the additional disruption of SMXL4 activity increases tissue production in the cambium region without that secondary phloem is formed. Using promoter reporter lines, we observe that SMXL4 and SMXL5 activities are associated with different stages of secondary phloem formation in the Arabidopsis stem. Based on genome-wide transcriptional profiling and expression analyses of phloem-related markers we conclude that early steps of phloem formation are impaired in smxl4;smxl5 double mutants and that the additional cambium-derived cells fail to establish phloem-related features. Our results show that molecular mechanisms determining primary and secondary phloem formation share important properties but differ slightly with SMXL5 playing a more dominant role in the formation of secondary phloem.