What is the most important part of a plant cell?

Mitochondria, nucleus, cell membrane, cell wall, cytoplasms, vacuoles etc are all important parts of a plant cell. Each part of the plant cell has specific functions for the smooth functioning of the plant cell, hence all are important. You can read about the Stems Cells – Types, Uses, Stem Cell Therapy in India in the given link.

Further readings:

1. Science & Technology Notes For UPSC – General Science Notes 
2. Plant Tissues – Classification, Definition, Types