Rg. Pinhero et al., MODULATION OF PHOSPHOLIPASE-D AND LIPOXYGENASE ACTIVITIES DURING CHILLING - RELATION TO CHILLING TOLERANCE OF MAIZE SEEDLINGS, Plant physiology and biochemistry, 36(3), 1998, pp. 213-224
Phospholipase D (phosphatidylcholine choline hydrolase, EC 3.1.4.4) an
d lipoxygenase activities (linoleate: oxygen oxidoreductase, EC 1.13.1
1.12) were analysed in chilling-susceptible and chilling-tolerant maiz
e (Zea mays L.) seedlings in relation to their chilling tolerance. Bef
ore chilling, phospholipase D activity in the leaf microsomal fraction
was 2-fold higher in the chilling-susceptible CO 316 when compared to
that of paclobutrazol-treated, chilling-tolerant CO 316. Phospholipas
e D activity in the heavy membrane fraction comprising chloroplast and
mitochondria showed a 3 to 4-fold increase during chilling and post-c
hilling periods, albeit with temporal variations. An increase in cytos
olic phospholipase D activity was observed only in CO 316 and CO 328.
Also, phospholipase D activity in the heavy membrane and cytosolic fra
ctions of roots increased in CO 316 during chilling and post-chilling
periods. Lipoxygenase activity was low in both leaves and roots of CO
328. Paclobutrazol treatment of CO 316 did not appear to affect the le
vel of cytosolic lipoxygenase activity in roots during the early part
of chilling and post-chilling, but increased the activity in leaves. T
he results suggest that during chilling and post-chilling periods, tem
poral variations in phospholipase D and lipoxygenase activities in bot
h leaves and roots of CO 316, CO 316P and CO 328 could result in diffe
rential metabolism of phospholipids. Enhanced degradation coupled with
low levels of turnover could lead to development of chilling injury i
n the tissue. (C) Elsevier, Paris.