Disruption and overexpression of auxin response factor 8 gene of Arabidopsis affect hypocotyl elongation and root growth habit, indicating its possible involvement in auxin homeostasis in light condition.
Disruption and overexpression of auxin response factor 8 gene of Arabidopsis affect hypocotyl elongation and root growth habit, indicating its possible involvement in auxin homeostasis in light condition.
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DOI：
10.1111/j.1365-313x.2004.02220.x
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
C. Tian;Hideki Muto;Kanako Higuchi;T. Matamura;K. Tatematsu;T. Koshiba;Kotaro T. Yamamoto
中科院分区：
文献类型：
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作者：
C. Tian;Hideki Muto;Kanako Higuchi;T. Matamura;K. Tatematsu;T. Koshiba;Kotaro T. Yamamoto
生长素反应因子（ARF）家族基因在控制植物对生长素的敏感性中起着重要作用。我们通过对ARF 8的T-DNA插入系（arf 8 -1）和过表达系（ARF 8 OX）的研究，对ARF 8在拟南芥中的功能进行了研究。arf 8 -1在白色、蓝色、红色或远红光条件下显示出长下胚轴表型，与在光照下显示短下胚轴的ARF 8 OX形成对比。arf 8 -1和arf 8 OX的根尖优势分别较强和较弱，侧根形成分别受到促进和抑制。arf 8 -1下胚轴对生长素的敏感性没有改变，外源生长素对下胚轴生长的抑制作用和高温对下胚轴生长的促进作用都没有改变。ARF 8在茎尖和根尖中组成型表达，在下胚轴中在光照条件下诱导表达。游离IAA含量减少约30%，在光生长的下胚轴的ARF 8 OX，但arf 8 -1和野生型之间的相似。三个GH 3基因的表达在arf 8 -1中减少，在ARF 8 OX中增加，表明它们是ARF 8转录控制的靶点。因为三种GH 3蛋白可能参与IAA的结合，如Staswick等人（2002）所建议的，并且因为三种GH 3基因中的两种是生长素诱导的，所以ARF 8可能通过调节GH 3基因表达以负反馈方式控制游离IAA水平。ARF家族基因似乎控制拟南芥生长素敏感性和稳态。
Auxin response factor (ARF) family genes play a central role in controlling sensitivity to the plant hormone auxin. We characterized the function of ARF8 in Arabidopsis by investigating a T-DNA insertion line (arf8-1) and overexpression lines (ARF8 OX) of ARF8. arf8-1 showed a long-hypocotyl phenotype in either white, blue, red or far-red light conditions, in contrast to ARF8 OX that displayed short hypocotyls in the light. Stronger and weaker apical dominance, and promotion and inhibition of lateral root formation were observed in arf8-1 and ARF8 OX respectively. Sensitivity to auxin was unaltered in arf8-1 hypocotyls with respect to growth inhibition caused by exogenously applied auxin and growth promotion induced by higher temperatures. ARF8 expression was observed constitutively in shoot and root apexes, and was induced in the light condition in hypocotyls. Free IAA contents were approximately 30% reduced in light-grown hypocotyls of ARF8 OX, but were similar between those of arf8-1 and wild type. Expression of the three GH3 genes was reduced in arf8-1 and increased in ARF8 OX, indicating that they are targets of ARF8 transcriptional control. Because the three GH3 proteins may be involved in the conjugation of IAA as suggested by Staswick et al. (2002), and because two of the three GH3 genes are auxin inducible, ARF8 may control the free IAA level in a negative feedback fashion by regulating GH3 gene expression. ARF family genes seem to control both auxin sensitivity and homeostasis in Arabidopsis.