Cloning and transformation of SCMV CP gene and regeneration of transgenic maize plants showing resistance to SCMV strain MDB
The coated protein gene of sugarcane mosaic virus ( SCMV CP gene) was cloned from maize (Zea mays L.) leaves showing dwarf mosaic symptoms by reverse-transcription polymerase chain reaction (RTPCR) with degraded primers. The results of sequencing and homologous comparison indicated that the cloned gene was from SCMV strain MDB, with 920 bp in length, including an open reading frame (ORF) encoding 219 amino acids and a 3' untranslated region (3'UTR). This gene was constructed into the expression vector p35SCPrBar in the antisense orientation, under the control of CaMV35S promoter, the plasmid p35SCPrBar was introduced into embryogenic calli induced from the immature embryos of maize inbred line 18-599(red) that is highly susceptible to SCMV-MDB via particle bombardment, the results of polymerase chain reaction (PCR) and Southern blotting hybridization demonstrated that the SCMV CP gene had been integrated into maize genome. The plants regenerated from T1 transgenic seeds were challenged with SCMV-MDB by artificial inoculation, as a result, transgenic progenies showed resistance to the inoculated virus to different extent. This work is beneficial for extending the planting regions for the elite inbred line 18-599(red).