Abstract:

Farnesyl diphosphate synthase catalyzes two consecutive condensations of isopentenyl diphosphate (IPP) with dimethylallyl diphosphate (DIMP) and the resultant geranyl diphosphate (GDP) to produce farnesyl diphosphate (FPP). Since FPP is the starting point of different branches of the pathway leading to the synthesis of large variety of isoprenoid end products, it is considered to play a key regulatory role of isoprenoid biosynthesis pathway. Previous reports proved that FPS regulated the sesquiterpenes biosynthesis in plants. To investigate the contribution of FPS to plant disease resistance, fps gene of Mentha spicata was transformed into and expressed in tobacco to observe its antifungal activity variation. The gene was cloned and inserted into binary vector under CaMV35S promoter to construct the plant constitutive expression vector pBinARfps. The leaf discs of tobacco (Nicotinan tabacium L. cv. K326) were transformed with fps gene via Agrobacterium-mediated transformation. Shoots were regenerated on MS medium supplemented with 30 mg/L Kan, 0.1 mg/L IAA and 0.5 mg/L BA and rooted on MS medium without hormone. PCR-Southern analysis proved foreign fps gene integration in 5 Kanamycin resistance plantlets (K-, K-6; K-17, K-19, K-35). Northern-blot indicated the foreign fps gene in transgenic plantlet was expressed at the transcriptional level. Disease challenge test of the detached leaves of transgenic plantlet by inoculation of Alternaria alternata showed that the resistance was dramatically enhanced compared with that of non-transgenic plants. The result implicated the potential application of fps gene in plant disease-resistance engineering.

Key words: Nicotinan tabacium, Farnesyl diphosphate synthase, Gene transformation, Alternaria alternata