Comparative study on the changes of proteins and oxidative enzymes occurring in protocorms and protocorm-like bodies systems of development in the orchid Dendrobium hookerianum

Abstract

Proteins and activities of antioxidant enzymes, including polyphenol oxidase (PPO), peroxidase (POX) and catalase (CAT), were evaluated in Dendrobium hookerianum during different stages of development of both protocorms and protocorm-like bodies (PLB) derived from seeds and axillary buds, respectively. The changes in the protein contents and the enzyme activities along with their isozyme patterns were compared between these two culture systems. It was found that the protein contents and the enzyme activities increased steadily over time during different stages of development in both the systems. Protein contents (4.57 mg/g fresh wt.) and activities of POX (21.9 U/mg protein), CAT (9.86 U/mg protein) were observed to be higher in PLB system as compared to protocorm system at stage IV of development. However, although the PPO activity increased gradually till the third stage of development, a decline was observed at stage IV wherein the activity was recorded to be more or less same in both the systems. Also, few proteins (~61, 50, 46, 32, 25, 16, 6 kDa) and new isozymes (POX 7, 8; CAT 2) were expressed only in PLB system of development. In general, high protein content and enzyme activities were detected in PLB system as compared to protocorm system. The results of the present study indicate that few proteins and isozymes could be regarded as specific biochemical markers for different stages of development of this medicinally important orchid.