บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Function and regulation of plant senescence-related nucleases.

Burd S., Sonego L., Jiao G., Lers A.

5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004. page 35

2004

บทคัดย่อ

Function and regulation of plant senescence-related nucleases.      Induction of nuclease and ribonuclease activities is characteristic to senescence in higher plants.These activities are likely to be involved in nucleic acids catabolism; however, the regulation and specific function of these enzymes and their encoding genes are unclear.LX ribonuclease transcript and protein were found to be induced during tomato natural leaf senescence, as well as, following ethylene treatment in young leaves.Consequence of inhibited LX expression is investigated in tomato.LX promoter can confer senescence-specific expression to the GUS repotrer gene in Arabidopsis.The bifunctional nuclease BFN1 is associated with Arabidopsis leaf senescence and its function is examined in knockout mutants.BFN1 promoter can activate GUS senescence-specific expression in Arabidopsis and tomato.The ability LX/bfn1 promoters to activate expression in conditions/tissues other than senescence are investigated.In parsley, senescence-related nuclease activities, PcNUC1 and PcNUC2 of ~43 and~40 kDa MW, respectively, were purified and characterized.

The two glycosylated nucleases are identical in the determined amino acid sequence and possibly differ in the sugar moiety.PcNUC2 nuclease was subjected to biochemical and kinetic analyses demonstrating its ability to degrade both RNA and DNA with higher efficiency manifested toward DNA.The ability of the enzyme to degrade double-stranded plasmid DNA following an initial endonucleolytic digest was demonstrated.PcNUC1/2 transcript is highly and specifically induced in both naturally and postharvest senescing parsley leaves but can be induced I young leaves by ethylene.The deduced amino acid sequence of PcNUC1/2 exhibits high homology to other senescence/PCD- related nucleases in plants, including BFN1.Senescence-associated plant nucleases are likely to have a major role in highly organized system for nucleic acid and phosphate recycling in the senescing tissues; however, it is possible they function also in other plant senescence-unrelated developmental stages/tissues.