A Balance between the Activities of Chloroplasts and Mitochondria Is Crucial for Optimal Plant Growth.

Energy metabolism in plant cells requires a balance between the activities of chloroplasts and mitochondria, as they are the producers and consumers of carbohydrates and reducing equivalents, respectively. Recently, we showed that the overexpression of purple acid phosphatase 2 (AtPAP2), a phosphatase dually anchored on the outer membranes of chloroplasts and mitochondria, can boost the plant growth and seed yield of by coordinating the activities of both organelles. However, when AtPAP2 is solely overexpressed in chloroplasts, the growth-promoting effects are less optimal, indicating that active mitochondria are required for dissipating excess reducing equivalents from chloroplasts to maintain the optimal growth of plants.