Changes in Ca2+ homeostasis and catalase activity have a key role in the regulation of the senescence rate of wheat leaves exposed to shading

C MARCHETTI; HF CAUSIN; LB PENA; SM GALLEGO; E PETRILLO

Buenos Airres

Congreso; VIII Society Free Radical Biology and Medicine-South American Group; 2013

In shaded wheat leaves, suppression of blue light (BL) triggers senescence. This phenomenon is correlated to an increase in oxidative stress symptoms and down regulation of CAT activity. Previous data suggest that this response may involve changes in Ca2+ homeostasis. To better understand the interaction among light quality, Ca2 the regulation of shade-induced senescence, detached leaves were placed in a growth chamber, and exposed to either blue (B,high BL transmittance) and/or green (G, very low BL transmittance) Lee® filters, in absence or presence of 0.7 mM verapamil, 4.0 mM EGTA or 8.0 mM 3-amino-1,2,4-triazole. At defined time points, leaf samples were analyzed for changes in chlorophyll and protein concentration, CAT, APX and SOD activities, and for gene expression profiles of CAn, CAT2 and two senescence markers (TaSAG1 and TaSAG3). BL transmittance delayed senescence rate either in leaves continuously exposed to the B filter, as well as in leaves previously exposed to the G filter. Analysis of antioxidant enzymes as well as gene expression profiles indicated that the effect of BL was suppressed when Ca2 activity were pharmacologically decreased. The interaction between BL, Ca2 is discussed.