Short communication Aggregate characteristics of callus derived from woody plant Eucommia ulmoides

Eucommia ulmoides was cultivated in suspended culture and formed aggregates with broad size spectrum. According to the mor-phological features, density and size, the aggregates were classified into daughter aggregate (DA), meristemoid-like aggregate (MA) and old aggregate (OA). DA can grow into MA, which proliferates DAs again at some vigorously growing points on their surface. Coexistence of DAs and MAs implies better conditions for callus growth. It was revealed that mechanical disintegration of callus into smaller size in the subculture has a negative effect on callus growth due to the damage of active cells located at the aggregate sur-face and/or the characteristics of original big aggregate which belongs to OA before fragmentation. The growth rates of spontaneous DA and MA were about two times higher than that of the disintegrated callus. As an approach for scaling-up process, spontaneously proliferated aggregates can provide the rapidly growing callus of E. ulmoides culture compared with the mechanically disintegrated callus