Primary study on anatomic and genetic characteristics of multi-loculus in Brassica juncea

Multi-loculus trait of a newly discovered Brassica juncea material J163 was investigated by paraffin-cut section method and hybridizations.Anatomic characteristics showed that the multi-loculus siliques of J163 were developed from 4 carpels.In the silique,4 petals surrounded the seeds,and 2 pseudo dissepiments paralleled,dividing the silique into 3 chambers.The middle chamber was larger than the other two.Two pseudo dissepiments were well developed with no obstacle nor degradation during silique filling period.No chimerism of multi-loculus and two-loculus siliques showed on single plants.Compared to bi-loculus materials,multi-loculus plants had both significantly higher seeds per silique and yield per plant,but lower thousand seeds weight and effective siliques per plant,which implied that multi-loculus with more seeds per silique was an effective trait to improve yields.Backcross and reciprocal cross results showed that the multi-loculus trait was controlled by recessive nuclear genes with no cytoplasmic effect.Differences were found on 2 pairs of genes on the mutlti-loculus loci between J163 and the bi-loculus material J248.It was not clear whether the 2 pairs of genes were genetically independent.However,it could be concluded that J163 was a new type of multi-loculus mustard.