Auxin influx carriers control vascular patterning and xylem differentiation in Arabidopsis thaliana.
Auxin influx carriers control vascular patterning and xylem differentiation in Arabidopsis thaliana.
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DOI：
10.1371/journal.pgen.1005183
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发表时间：
2015-04
期刊：
影响因子：
4.5
通讯作者：
Ibañes M
中科院分区：
文献类型：
--
作者：
Fàbregas N;Formosa-Jordan P;Confraria A;Siligato R;Alonso JM;Swarup R;Bennett MJ;Mähönen AP;Caño-Delgado AI;Ibañes M
生长素是植物生长发育所必需的激素。生长素内流载体AUX1/LAX将生长素输送到细胞内，而生长素外流载体PIN将生长素泵出细胞。外流载体在枝条维管构型中起着重要作用，但外流载体对枝条维管系统的作用尚不清楚。在这里，我们结合理论和实验方法来破译生长素内流载体在拟南芥花序茎中维管组织形成和分化中的作用。我们的理论分析预测，流入的载体促进了周期模式的形成，并调节了生长素最大值的周期性。一致地，我们观察到生长素内流载体Aux1lax1lax2lax3的四个突变体植株中的维管束越来越少，间距越来越大。此外，我们还发现AUX1/LAX载体促进了茎和根组织中木质部的分化。内流载体增加了细胞质生长素信号，从而促进了分化。除了生长素的这种细胞质作用外，我们的计算模拟还提出了细胞外生长素作为木质部分化抑制因子的作用。综上所述，我们的研究表明，生长素内流载体AUX1/LAX调节植物的维管模式和分化。拟南芥(Arabitopsis Thaliana)植物地上部的维管组织以维管束的形式组织起来，并以保守的周期性放射状排列。众所周知，这种模式的出现是由于植物激素生长素的积累，生长素由所谓的外流和内流载体主动运输。外流载体促进生长素从细胞内到细胞外空间的极性运输，而内流载体以非极性方式将生长素从细胞外泵到细胞内部。虽然生长素外流载体在这种模式的出现中的作用已经被认识到，但生长素外流载体的作用到目前为止仍然被忽视。在这项研究中，我们采用理论和实验相结合的方法来揭示生长素内流载体在植物维管系统形成中的作用。我们的分析揭示了生长素内流载体在血管构型中的主要作用，揭示了生长素内流载体调节水分运输维管细胞(称为木质部细胞)的图案化和分化。
Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants. The vascular tissues in the shoot of Arabidopsis thaliana (Arabidopsis) plants are organized in vascular bundles, disposed in a conserved periodic radial pattern. It is known that this pattern emerges due to the accumulation of the phytohormone auxin, which is actively transported by the so-called efflux and the influx carriers. Efflux carriers facilitate polar transport of auxin from inside the cell to the extracellular space, while influx carriers pump auxin from outside the cell to its interior in a non-polar manner. Although a role for auxin efflux carriers in the emergence of this pattern has been recognized, the role of auxin influx carriers has remained hitherto neglected. In this study, we combine theoretical and experimental approaches to unravel the role of the auxin influx carriers in the formation of plant vasculature. Our analysis uncovers primary roles for the auxin influx carriers in vascular patterning, revealing that auxin influx carriers modulate both patterning and the differentiation of the water transporting vascular cells, known as xylem cells.
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