The loci of perception for phytochrome control of internode growth in light-grown mustard: Promotion by low phytochrome photoequilibria in the internode is enhanced by blue light perceived by the leaves
✍ Scribed by Jorge J. Casal; Harry Smith
- Publisher
- Springer-Verlag
- Year
- 1988
- Tongue
- English
- Weight
- 626 KB
- Volume
- 176
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Under continuous white light (WL), extension growth of the first internode in Sinapis alba L. was promoted by low red (R): far-red (FR) ratios reaching the stem and-or the leaves. Conversely, the growth promotion by end-of-day light treatments was only triggered by FR perceived by the leaves and cotyledons, while FR given to the growing internode alone was totally ineffective. Continuous WL + FR given to the internode was also ineffective if the rest of the shoot remained in darkness. Both the background stem growth, and the growth promotion caused by either an end-of-day FR pulse or continuous WL + FR given to the internode, increased with increasing fluence rates of WL given to the rest of the shoot. The increase by WL of the growth-stimulatory effect of low phytochrome photoequilibria in the internode appears to be mediated by a specific blue-light-absorbing photoreceptor, as blue-deficient light from sodium-discharge lamps, or from filtered fluorescent tubes, promoted background stem growth similarly to WL but did not amplify the response to the R: FR ratio in the internode. Supplementing the blue-deficient light (94 gmol.m-Z-s -1) with low fluence rates of blue (< 9 gmol.m 2. s-a) restored the promotive effect of low R:FR reaching the internode.