Nitric oxide enhances plant ultraviolet-B protection up-regulating gene expression of the phenylpropanoid biosynthetic pathway

TOSSI, V; AMENTA, M; LAMATTINA, L.; CASSIA, R.

plant cell and environment

Willey

Año: 2011 vol. 34 p. 909 - 921

1365-3040

The link between UV-B, nitric oxide (NO) and phenylpropanoid biosynthetic pathway (PPBP) was studied in maize and Arabidopsis. The transcription factor (TF) ZmP regulates PPBP in maize. A genetic approach using P-rr (ZmP+) and P-ww (ZmP-) maize lines demonstrate that: (i) NO protects P-rr leaves but not P-ww from UV-B-induced ROS and cell damage, (ii) NO increases flavonoids and anthocyanins content and prevent chlorophyll loss in P-rr but not in P-ww and (iii) the NO scavenger cPTIO blocks the UV-B-induced expression of ZmP and their targets CHS and CHI suggesting that NO plays a key role in the UV-B-regulated PPBP. Involvement of endogenous NO was studied in Arabidopsis NOD plants expressing a NO Dioxygenase gene under the control of a DEX-inducible promoter. Expression of HY5 and MYB12, TFs involved in PPBP regulation, was induced by UV-B, reduced by DEX in NOD plants and recovered by subsequent NO treatment. C4H regulates the synapate esters synthesis and is UV-B-induced in a NO-independent pathway. Data indicate that UV-B perception increases NO concentration, which protects plant against UV-B by two ways (i) scavenging ROS, and (ii) upregulating the expression of HY5, MYB12 and ZmP, resulting in the PPBP activation.