open access

https://hdl.handle.net/2115/44104

Phytochrome-mediated growth inhibition of seminal roots in rice seedlings

英語

2009-11

Blackwell Publishing

Physiologia Plantarum

137(3)

289-297

In rice (Oryza sativa) seedlings, continuous white-light irradiation inhibited the growth of seminal roots but promoted the growth of crown roots. Here, we examined the mechanisms of photoinhibition of seminal root growth. Photoinhibition occurred in the absence of nitrogen, but increased with increasing nitrogen concentrations. In the presence of nitrogen, photoinhibition was correlated with coiling of the root tips. The seminal roots were most photosensitive 48-72 h after germination during the 7-d period after germination. White-light irradiation for at least 6 h was required for photoinhibition, and the Bunsen-Roscoe law of reciprocity was not observed. Experiments with phytochrome mutants showed that far-red light was perceived exclusively by phyA, that red light was perceived by both phyA and phyB, and phyC had little or no role in growth inhibition or coiling of the seminal roots. Fluence-response curve analyses also showed that phyA and phyB control very low fluence response and low fluence response, respectively, in the seminal roots. This was essentially the same as the growth inhibition previously observed at the late stage of coleoptile development (80 h after germination). These results also suggest that other blue-light photoreceptors are involved in growth inhibition of the seminal roots. The photoperceptive site for the root growth inhibition appeared to be the roots themselves. All three phytochrome species of rice were detected immunochemically in roots.

学術雑誌論文

Accepted Manuscript

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0031-9317