No abstract

The activity of the enzyme 3‐hydroxy‐3‐methlglutaryl‐coenzyme A reductase (HMGR, EC 1.1.1.34) is highly expressed in 4‐day‐old etiolated seedlings of normal (cv. DeKalb XL72AA), dwarf (d5) and albino (lw3) maize (Zea mays L.). HMGR activity of maize seedlings appeared to be exclusively associated with the microsomal rather than the plastidic fraction of maize cells. Maize tissues with high meristematic activity such as germinating seeds, leaf bases, root tips and the site of origin of lateral roots contained high levels of microsomal HMGR activity. The activity of HMGR extracted from leaf tips of normal, dwarf and albino maize seedlings is regulated by light. Microsomal HMGR activity from leaf tips of 4‐day‐old maize seedlings was inhibited significantly following exposure to strong light (600 μmol m−2 s−1) for more than 10 h. By comparison, microsomal HMGR activity from leaf bases and root tips of maize was not inhibited by exposure to strong light. These results suggest that the microsomal HMGR which is highly expressed in maize may be related to sterol biosynthesis and membrane biogenesis rather than plastidic‐associated isoprenoid synthesis and that light may regulate HMGR activity indirectly by increasing cell differentiation.

No abstract

No abstract

No abstract