Overexpression of light-dependent PORA or PORB in plants depleted of endogenous POR by far-red light enhances seedling survival in white light and protects against photooxidative damage
Article first published online: 29 AUG 2003
© 1997 Blackwell Science Ltd and the Society for Experimental Biology
The Plant Journal
Volume 12, Issue 3, pages 649–658, September 1997
How to Cite
Sperling, U., van Cleve, B., Frick, G., Apel, K. and Armstrong, G. A. (1997), Overexpression of light-dependent PORA or PORB in plants depleted of endogenous POR by far-red light enhances seedling survival in white light and protects against photooxidative damage. The Plant Journal, 12: 649–658. doi: 10.1046/j.1365-313X.1997.00649.x
- Issue published online: 29 AUG 2003
- Article first published online: 29 AUG 2003
- Received 18 December 1996; revised 19 March 1997; accepted 13 May 1997.
- Cited By
The structurally related light-dependent protochlorophyllide (Pchlide) oxidoreductases PORA and PORB mediate the only light-requiring step in chlorophyll (Chl) biosynthesis in higher plants. Correlative evidence suggests that some in vivo functions of PORA and PORB may be unique, including a postulated photoprotective role for PORA. For example, wild-type Arabidopsis thaliana seedlings grown in non-photooxidative far-red light (cFR) resemble those grown in white light (WL), but they are yellow and do not green normally thereafter in WL. This defect is accompanied by the absence of detectable PORA and reduced levels of PORB expression. Here, direct evidence is provided that the presence of POR, either as PORA or PORB, can confer photoprotection in plants. In contrast to the wild-type, the plastids of transgenic PORA- or PORB-overexpressing Arabidopsis seedlings grown in cFR possess extensive prolamellar bodies. Upon a subsequent shift to WL, POR-overexpressing seedlings develop thylakoid membranes, accumulate large amounts of Chl and are viable at fluence rates lethal to the wild-type. Intriguingly, the plastid membrane architectures of greening transgenic seedlings seem to depend on whether PORA or PORB has been over-produced. POR-overexpressing seedlings shifted from cFR to WL of fluence rates from 20 to 500 μE m−2 sec−1 accumulate substantially higher amounts of Chl than does the wild-type. Furthermore, the WL fluence rate that permits maximal Chl accumulation increases from 8 μE m−2 sec−1 in the wild-type to 125 μE m−2 sec−1 in transgenic seedlings. POR Overexpression during growth in cFR also correlates with a fourfold decrease in the steady-state content of Pchlide, a potentially lethal photosensitizer.