柑橘胚性愈伤组织的褐化与转化

Threre are significant differences in tansformation effieiency between different citrus embryogenic cailuses. Embryogenic calluses of 11 citrus genotypes ( including Citrus reticulata, C. sinensis，C. Paradisi, Fortunella crassifolia, etc), were assessed for Agrobacterium tumefaciens mediated transformation potentials. GUS positive callus lines from 10 genotypes were produced and the transformation result indicated that there was remarkable relatvity between transformation efficiency and citrus callus browning. Dark brown callus also yielded higher transformation efficiency, while weak or no brown calluses gave lower one. Callus from C. reticulata brown severely, and the transformation efficiency reached up to 80%. Calluses from C. sinensis brown variously from borwn to weak or no brown, and the transformation efficiency was 0-20%. F. crossifolia and C. Paradise were between them, the transformation efficiency was 20% and 6%, respectively. Further study indicated that total phenolic content was positively correlated with citrus callus browning. As a result, total phenolic content affect citrus callus browning thus influence transformation efficiency. The possible mechenism was that total phenolic content was related to induction of vir genes and transfer of T一DNA.