Arabidopsis thaliana, but higher with dhar1 and dhar2
of Arabidopsis thaliana. different gene family.
Maybe they belong to
Table 1. The dhar genes of different plants species in
Arabidopsis thaliana (dhar1)
Arabidopsis thaliana (dhar3)
Toyonaka Malus domestica Vitis vinifera Lycopersicon esculentum Solanum tuberosum Nicotiana tabacum
Fig.5 Homology tree of deduced amino acid sequences of the dhar gene from different plants (as in Table 1)
AsA is an essential mineral elements to maintain health of humans. It is reported that althought the current recommended dietary allowance for vitamin C is 75-90mg, an increase to 200mg has been suggested (Levine et al., 1996). Such an increase would require foodstuffs rich in AsA. However, DHAR play an important role in recycling of AsA in plants, since it can catalyzes ascorbic acid oxidized form DHA to AsA, thereby regulating redox state of AsA. Therefore, cloning dhar gene is very important to increase the content of AsA and have a better understanding of the gene structure and functions.
Agric. Biol. J. N. Am., 2010, 1(4): 726-730
SON-PCR can isolate DNA regions located on either side of a known DNA sequence and have high specificity, relying on only two amplification reactions with two of three nested sequence-specific primers. Therefore, it seems a very efficient and widely application technique for the rapid identification of large unknown DNA regions (Antal et al., 2004). In this study, we firstly cloned a fragment of strawberry dhar gene conserved region. Then based on the obtained conserved regions sequences, we designed two pairs of nested primers to isolate strawberry dhar gene flanking sequences by SON-PCR. At last, we obtained a 1374bp sequence by splicing the isolated flanking fragments with the conserved region fragment. Homology analysis of deduced amino acid sequence on the Fadhar showed that it shared high homology with different plants species, indicating that it is a relatively conservative gene in plants. In addition, the amino acid homology tree showed that three of Arabidopsis thaliana dhar gene did not fell into one cluster, indicating that dhar gene may be encoded by a multi-gene family. At present, only a few genes of dhar gene family in plants have been cloned. So it is very important to clone all the genes of the family, which will help to undetstand the composition and function of the gene family.
ACKNOWLEDGMENTS The present research is supported by the Foundation for the Educational Commission of Sichuan Province, China (07ZZ023; 2006ZD004).
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