Livanos Pantelis, Giannoutsou Eleni, Apostolakos Panagiotis, Galatis Basil
a Department of Botany; Faculty of Biology; University of Athens ; Athens , Greece.
Plant Signal Behav. 2015;10(3):e984531. doi: 10.4161/15592324.2014.984531.
The data presented in this work revealed that in Zea mays the exogenously added auxins indole-3-acetic acid (IAA) and 1-napthaleneacetic acid (NAA), promoted the establishment of subsidiary cell mother cell (SMC) polarity and the subsequent subsidiary cell formation, while treatment with auxin transport inhibitors 2,3,5-triiodobenzoic acid (TIBA) and 1-napthoxyacetic acid (NOA) specifically blocked SMC polarization and asymmetrical division. Furthermore, in young guard cell mother cells (GMCs) the PIN1 auxin efflux carriers were mainly localized in the transverse GMC faces, while in the advanced GMCs they appeared both in the transverse and the lateral ones adjacent to SMCs. Considering that phosphatidyl-inositol-3-kinase (PI3K) is an active component of auxin signal transduction and that phospholipid signaling contributes in the establishment of polarity, treatments with the specific inhibitor of the PI3K LY294002 were carried out. The presence of LY294002 suppressed polarization of SMCs and prevented their asymmetrical division, whereas combined treatment with exogenously added NAA and LY294002 restricted the promotional auxin influence on subsidiary cell formation. These findings support the view that auxin is involved in Z. mays subsidiary cell formation, probably functioning as inducer of the asymmetrical SMC division. Collectively, the results obtained from treatments with auxin transport inhibitors and the appearance of PIN1 proteins in the lateral GMC faces indicate a local transfer of auxin from GMCs to SMCs. Moreover, auxin signal transduction seems to be mediated by the catalytic function of PI3K.
这项研究中呈现的数据表明，在玉米中，外源添加的生长素吲哚 - 3 - 乙酸（IAA）和1 - 萘乙酸（NAA）促进了副卫细胞母细胞（SMC）极性的建立以及随后副卫细胞的形成，而用生长素运输抑制剂2,3,5 - 三碘苯甲酸（TIBA）和1 - 萘氧基乙酸（NOA）处理则特异性地阻断了SMC的极化和不对称分裂。此外，在幼嫩的保卫细胞母细胞（GMC）中，PIN1生长素外排载体主要定位在GMC的横向面上，而在成熟的GMC中，它们出现在与SMC相邻的横向面和侧面上。鉴于磷脂酰肌醇 - 3 - 激酶（PI3K）是生长素信号转导的活性成分，且磷脂信号传导有助于极性的建立，因此用PI3K的特异性抑制剂LY294002进行了处理。LY294002的存在抑制了SMC的极化并阻止了它们的不对称分裂，而外源添加NAA与LY294002的联合处理则限制了生长素对副卫细胞形成的促进作用。这些发现支持了生长素参与玉米副卫细胞形成的观点，生长素可能作为不对称SMC分裂的诱导剂发挥作用。总体而言，生长素运输抑制剂处理的结果以及PIN1蛋白在侧面GMC面中的出现表明生长素从GMC向SMC发生了局部转移。此外，生长素信号转导似乎由PI3K的催化功能介导。
