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

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

Buenos Aires

Congreso; Radical Biology and Medicine-South American Group (VIII SFRBM-SAG); 2013

In shaded wheat leaves, suppression of blue light (BL) triggers senescence. This phenomenon is correlated to an increase inoxidative stress symptoms and down regulation of CAT activity. Previous data suggest that this response may involve changesin Ca2+ homeostasis. To better understand the interaction among ight quality, Ca2+ availability and the antioxidant metabolism inthe regulation of shade-induced senescence, detached leaveswere 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 mMverapamil, 4.0 mM EGTA or 8.0 mM 3-amino-1,2,4-triazole. At defined time points, leaf samples were analyzed for changes inchlorophyll and protein concentration, CAT, APX and SOD activities, and for gene expression profiles of CAt1, CAT2 andtwo 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 antioxidantenzymes as well as gene expression profiles indicated that the effect of BL was suppressed when Ca2+ availability or CATactivity were pharmacologically decreased. The interaction between BL, Ca2+ homeostasis and the antioxidant metabolismis discussed.