Abstract:

X4(Pseudomonas fluorescens biovar Ⅲ) is a biological strain screened from melon surface by direct biological determination method. The strains did not produce antibiotic 2,4-DAPG, but had good control ability for many melon post harvests diseases. In this paper, X4-G was constructed by integrating Tn5 transposon comprising 2,4-DAPG synthetic genetic cluster into X4 genome. It was confirmed being successfully inserted by PCR and TLC test, and could exist stably in X4-G strains. Both X4 and X4-G strains showed inhibition to post harvests diseases pathogens Fusarium SPP. and Trichothecium roseum in plate antagonism experiment. Strains X4 and X4-G had over 80% bio-control efficacy to T. roseum in melon, and X4-G was prior to X4. The results showed that the recombinant X4-G with 2,4-DAPG synthesis genes could improve the bio-control ability to melon post harvest diseases.

Key words: bio-control, melon post harvest disease, genetic improvement, 2,4-DAPG, transposon

摘要：

X4(Pseudomonas fluorescens biovar Ⅲ)是利用直接生物测定的方法从甜瓜表面分离得到的生防菌株,此菌株并不产生抗生素2,4-DAPG,但对多种甜瓜采后病害具有较好生防能力。本试验利用Tn5转座子携带2,4-DAPG合成基因簇整合到X4上,得到改良菌株X4-G。经PCR检测和TLC检测导入成功,并且确定可在改良菌株X4-G中稳定存在。拮抗试验中,菌株X4和X4-G对甜瓜采后病害病原菌Fusarium spp.和Trichothecium roseum都有一定的抑制作用。菌株X4和工程菌株X4-G在甜瓜上对T. roseum生防效果均达到80%以上,且X4-G的防效优于X4。表明通过染色体整合抗生素2,4-DAPG合成基因可提高甜瓜采后病害生防菌株生防能力。

关键词: 生物防治;甜瓜采后病害;遗传改良;2,4-二乙酰基间苯三酚;转座子