| Phytoalexins are low-molecular-weight antmicrobial compounds utilized by plant to resist biological or none biological invading factors, which is secondary metabolic product. They are important fungi resistant materials and thought to be an important mechanism in plant resistance for their induced synthesis after infection of pathogen. They have great structural diversity, and varied in biosynthetic pathways. It had been reported that introduction of gene of key enzyme in phytoalexins biosynthesis increased its expression level and the accumulation of phytoalexin, resulted in increased resistance to pathogen.Fan and Peng isolated two phytoalexins in rice inoculated with incompatible race of Magnaporthe grisea. They accumulated in rice after 48 hours. According to their chemical structure, tryptamine is precursor of these two phytoalexins. It can be inferred that TDC involved in rice resistance reaction to Magnaporthe grisea.6 genes were found from rice genome database containing pyridoxal-dependent decarboxylase conserved domain. These fragments had been amplified from genomic DNA, and cloned. A fragment of RICETDC5 had been amplified from cDNA library of resistant rice and used to screen the cDNA library.Results of Northern blotting indicated that infection of Magnaporthe grisea could significantly induce the RICETDC5 transcripts, and the accumulation level of RICETDC5 were higher and more durable in incompatible race infected rice leaves than that in compatible race infected leaves. This suggested that RICETDC5 is typical of a gene involved in the disease resistance. |
