Molecular Cloning Of The Gene JcTAW1 Associated With Inflorescence Development In Jatropha Curcas And Unique Characterization Of Its Transgenic Tobacco Plants

Jatropha curcas is an important energy plant with a prevalent concern, due to its numerous advantages including high level of seed oil suitable for biodiesel conversion, no competition with food crops for arable lands, and large potential to ameliorate ecological environments. However, its industry is severely restricted by its low seed yield. In terms of angiosperm plants, a manner to foster flower development leading to more number of flower organs and ultimately more seeds or fruits is regarded as an effectual route for yield increase. Therefore, any studies on the genes associated with flower development in J. curcas would be beneficial to improve its seed productivity through the approaches of genetic engineering. Rice TAW1 was proven as a high-productivity gene that can facilitate the inflorescence development to form more number of spikes and flowers. In this study, we attempted to clone the ortholog(JcTAW1) of the rice TAW1 gene from J. curcas, and introduce it into tobacco, and finally conduct a unique characterization of its transgenic tobacco plants for its functional evaluation. The major results obtained are shown as follows:(1) Gene cloning of JcTAW1 and construction of its plant expression vectorUsing the genomic DNA of J. curcas as template, the full length of JcTAW1 gene was successfully amplified by gene-specific primers via two consecutive rounds of PCR. The amplified product was directly subcloned into a pBI121-derivative plasmid to generate the plant expression vector pBI(JcTAW1) that was further verified by sequencing. The coding region of JcTAW1 is 642 bp, encoding a protein of 213 aa.Bioinformatic analysis indicated that JcTAW1 belonged to the ALOG family, the orthologs of which exist in both monocot and dicot plants.(2) Obtainment of JcTAW1 transgenic tobacco plants and their unique feature analysisThe plant expression vector pBI(JcTAW1) was transformed into the Agrobacterium tumefaciens strain LBA4404. Through the leaf disc transformation by Agrobacterium infection and subsequent multiplex PCR identification, the positivetransgenic tobacco plants of JcTAW1 gene were obtained.From the preliminary analysis on the F0 generation of JcTAW1-transgenic tobacco plants, the total number of flowers and lateral branches in three transgenic lines(JcTAW1-3,6,7) were all higher than that of the wild-type control. Thus, the F1 generation of these three transgenic lines was subjected to a comprehensive characterization. The correlated results indicated that the total number of flowers and lateral branches as well as the number of flowers per branch were significantly higher in all three transgenic lines than in the wild-type tobacco. In addition, JcTAW1-transgenic tobacco plants were surprisingly found of dominant growth over wild-type tobacco, with a greater plant height and more intensive root system.In conclusion, introduction of the JcTAW1 gene into tobacco can foster the development of both inflorescence and root in its transgenic plants, implying a potential route to increase the seed yield of J. curcas. Moreover, it can be also prospected that the JcTAW1 gene is used for plant genetic improvement on the root-associated traits such as drought-tolerance and mineral nutrition uptake.