**6. Mutation types induced by distant grafting in soybean**

In our research on distant–graft in soybean, we have observed the same morphological mutation as those in mungbean reported by Zhang *et al*. (2002). These mutation consist of the variation of growth habit, growth period, seed size, seed coat color, leaf shape, seed germination capacity and so on, which offer the basic materials for soybean breeding and gene mining. Through the directional selection on the progeny of distant-grafting, we have gained the excellent soybean lines characteristic of good quality, early mature, tolerance to drought and chilling, resistance to stress, lodging and diseases.

The results of karyotype analysis revealed that there was ploidy variation of chromosomes in the offspring of distant grafting in soybean. About 20% of the root tip cell showed chromosomal abnormalities (2n=36 or 38) for some individuals in G1 generation (unpublished). Certainly, there will be other variation such as photosynthetic capacity, isozymes and genes waiting for further research.
