Exogenous application of abscisic acid to shoots promotes primary root cell division and elongation.
Exogenous application of abscisic acid to shoots promotes primary root cell division and elongation.
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DOI：
10.1016/j.plantsci.2019.110385
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
Qijun Xie;J. Essemine;Xiaochen Pang;Haiying Chen;Weiming Cai
中科院分区：
文献类型：
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作者：
Qijun Xie;J. Essemine;Xiaochen Pang;Haiying Chen;Weiming Cai
根衍生脱落酸(ABA)是已知的调节枝条生理的物质，如气孔关闭。相反，鲜为人知的是，丛生芽衍生的ABA对基瓣的调节作用。在这里，我们报道了通过外源ABA在地上部施加ABA来模拟地上部ABA的积累，从根本上刺激初生根(PR)的生长。ABA处理促进根细胞分裂，表现为分生组织大小和细胞数目的增加以及有丝分裂标记细胞CyCB1；1：：GFP的强度。虽然ABA报告系Rab18：：GFP显示子叶中ABA含量增加，但ABA处理后根ABA含量没有变化。喷施丛枝ABA可使基瓣生长素运输增加114%。用生长素运输抑制剂2，3，5-三碘苯甲酸(TIBA)减弱基瓣生长素通量，可以消除ABA促进的PR生长，说明ABA通过增加基瓣生长素运输来促进PR生长。根细胞伸长以伸长区(EZ)前7个细胞的总长度为指标，经ABA处理后，根细胞伸长增加了56%。8-羟基-1，3，6-三磺酸三钠盐染色显示，根EZ的细胞壁被ABA碱化。较高的pH促进了PR的生长和细胞的伸长。因此，芽-ABA通过使细胞壁碱化来促进细胞伸长。根据我们的结果，我们提供了一个具有代表性的详细模型，说明ABA对PR生长的基瓣调控作用。
Root-derived abscisic acid (ABA) is known to regulate shoot physiology, such as stomata closure. Conversely, the basipetal regulatory effect of shoot-derived ABA is poorly understood. Herein, we report that simulation of shoot-ABA accumulation by exogenous application of ABA to shoots basipetally stimulates primary root (PR) growth. ABA applied to shoots accelerates root cell division, as evidenced by the increase in meristem size and cell number and the intensity of CYCB1;1::GFP (a mitosis marker). Root ABA content was not changed following shoot ABA application, although the ABA reporter line RAB18::GFP showed an increase in ABA in the cotyledons. Shoot-ABA application increases basipetal auxin transport by 114 %. Shoot-ABA-promoted PR growth can be abolished by attenuating basipetal auxin flux using 2,3,5-triiodobenzoic acid (TIBA, an auxin transport inhibitor), demonstrating that ABA promotes PR growth by increasing basipetal auxin transport. Root cell elongation, evaluated by the total length of the first 7 cells in the elongation zone (EZ), was increased by 56 % following shoot-ABA application. The cell walls of the root EZ were alkalinized by ABA, as exhibited by 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt staining. Higher pH promotes both PR growth and cell elongation. Thus, shoot-ABA promotes cell elongation by alkalinizing the cell wall. In light of our results, we provide a representative detailed model of the basipetal regulatory effect of ABA on PR growth.