Phytochromes inhibit hypocotyl negative gravitropism by regulating the development of endodermal amyloplasts through phytochrome-interacting factors
Phytochromes inhibit hypocotyl negative gravitropism by regulating the development of endodermal amyloplasts through phytochrome-interacting factors
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DOI：
10.1073/pnas.1011066108
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发表时间：
2011-01-25
影响因子：
11.1
通讯作者：
Choi, Giltsu
中科院分区：
文献类型：
--
作者：
Kim, Keunhwa;Shin, Jieun;Choi, Giltsu
光敏色素是调节植物发育各个方面的红光和远红光感受器。光敏色素鲜为人知的作用之一是抑制下胚轴负向地性，这是指下胚轴负向地性的丧失并导致红光或远红光下的随机生长方向。这种光响应使幼苗从土壤中出来后向蓝光弯曲，并在覆盖物存在的情况下增强幼苗的生长。光敏色素通过抑制四种光敏色素相互作用因子（PIF1、PIF3、PIF4、PIF5）来抑制下胚轴负向向性，如黑暗生长的 pif1 pif3 pif4 pif5 四重突变体的下胚轴向地性所示。我们发现，光敏色素通过在红光或远红光下将淀粉填充的重力感应内胚层淀粉体转化为其他具有叶绿体或异质体特征的质体来抑制负向地性，而PIF通过在黑暗中抑制内胚层淀粉体向异质体的转化来促进负向地性。通过分析用内皮层特异性 SCARECROW 启动子表达 PIF1 的转基因植物，我们进一步表明内胚层 PIF1 足以抑制内胚层淀粉体向黄化体的转化以及 pif 四重突变体在黑暗中的下胚轴负向地性。尽管光敏色素在向地性和叶绿体发育中的功能通常被认为是不同的，但我们的结果表明这两个功能密切相关。
Phytochromes are red and far-red light photoreceptors that regulate various aspects of plant development. One of the less-understood roles of phytochromes is the inhibition of hypocotyl negative gravitropism, which refers to the loss of hypocotyl gravitropism and resulting random growth direction in red or far-red light. This light response allows seedlings to curve toward blue light after emergence from the soil and enhances seedling establishment in the presence of mulch. Phytochromes inhibit hypocotyl negative gravitropism by inhibiting four phytochrome-interacting factors (PIF1, PIF3, PIF4, PIF5), as shown by hypocotyl agravitropism of dark-grown pif1 pif3 pif4 pif5 quadruple mutants. We show that phytochromes inhibit negative gravitropism by converting starch-filled gravity-sensing endodermal amyloplasts to other plastids with chloroplastic or etioplastic features in red or far-red light, whereas PIFs promote negative gravitropism by inhibiting the conversion of endodermal amyloplasts to etioplasts in the dark. By analyzing transgenic plants expressing PIF1 with an endodermis-specific SCARECROW promoter, we further show that endodermal PIF1 is sufficient to inhibit the conversion of endodermal amyloplasts to etioplasts and hypocotyl negative gravitropism of the pif quadruple mutant in the dark. Although the functions of phytochromes in gravitropism and chloroplast development are normally considered distinct, our results indicate that these two functions are closely related.