重组生防菌308R(pKSH)的遗传稳定性研究

工程菌308R（pKSH）携带有梨火疫欧文氏杆菌的hrpN基因，能产生并分泌诱导植物抗病性蛋白-Harpin。该工程菌在无选择压培养基中生长50代，带有重组质粒pKSH的细胞占总菌量的23．1％，对照菌308R（pCPP430）的细胞占4．75％。将工程菌和对照菌喷雾到番茄叶面，保湿条件下的13d内，叶面菌量维持在10^5cfu／cm^2以上，自然条件下的5d内，菌量维持在10^4cfu／cm^2以上，其间308R（pKSH）的稳定性一直高于对照菌。因此证明工程菌308R（pKSH）比对照菌308R（pCPP430）稳定性有所提高，但还是不够理想。讨论了该工程菌不稳定的原因以及改进途径。

Genetic Stability of a Recombinant Biocontrol Bacteria 308R (pKSH)

Biocontrol bacteria 308R(pKSH) with hrpN of Erwinia amyloyora. It can secrete the Harpin protein which can induce plant resistance. After successive growth in antibiotic-free LB medium for 50 generations, only 23.1% of the cell still retained the plasmid pKSH, in comparison with 4.75% of the cosmid pCPP430. Sprayed onto the leaves of tomato, the recombinant strain maintained a population density of over 10~ 5 cfu/cm~ 2 when kept under high humidity in thirteen days, but if without humidity, the strain keep 10~ 4 cfu/cm~ 2 over in five days. On the tomato leaves, the stability of the recombinant strain 308R(pKSH) was higher than the strain 308R(pCPP430). The experiment indicated that the recombinant strain 308R(pKSH) had higher stability compared with the strain 308R(pCPP430), but that was not enough. In this paper reasons for unstability and strategies for improving were discussed for the recombinant strain.