The Effect of Cd on Chlorophyll and Light-Harvesting Complex II Biosynthesis in Greening Plants

The effect of Cd on chlorophyll (Chl) as well as on light-harvesting complex II (LHCII) accumulation, has been examined during the early stages of development in etiolated Phaseolus vulgaris leaves exposed to intermittent light-dark cycles. We found that at the Cd concentrations studied, both Chl and LHCII accumulation were drastically reduced, although the LDS-solubilized total leaf protein level remained unaffected. However, on the basis of total chlorophyll present, the amount of stabilized LHCII was similar in both Cd-treated and nontreated samples. Additionally, the thylakoid-bound protease known to degrade LHCII, was found to be inhibited by Cd treatment both in vivo and in vitro. Finally, Northern hybridization analysis indicated that Cd affects LHCII accumulation by reducing drastically the steadystate level of Lhcb transcripts