บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Inhibition of dark-induced senescence of pelargonium cutting by gibberellic acid and the involvement of PeGAST-like genes

Rosenvasser S., Mayak S., Friedman H.

5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004, p.78

2004

บทคัดย่อ

Inhibition of dark-induced senescence of pelargonium cutting by gibberellic acid and the involvement of PeGAST-like genes  Senescence of pelargonium cuttings is induced by darkness to which cutting are exposed during shipment.Dark-induced senescence of the cuttings’ young leaves is mainifested by both chlorophyll breakdown and increase in the cystein protease homolog SAG12 expression.Dark-induced senescence is also associated with a gradual increase in reactive oxygen species (ROS) accumulation.Microscopic analysis revealed that ROS accumulate in the cell wall during early stages of dark treatment.Gibberellic acid treatment before or o­n the third day of the dark period inhibits the dark-induced senescence ofthe pelargonium cutting and ROS accumulation, while treatment o­n the fourth day failed to inhibit senescence.

The possible involvement of GA-unregulated GAST-like genes in GA3-inhibition of dark-induced senescence has been examined.Genes of the CAST family which are probably secreted to the apoplast, contain twelve cystein residues in their C-terminus that may function as redox modulators.Towards elucidating the role of PeGAST-like genes in GA3-inhibition of dark-induced senescence, two GAST homologs have been cloned from pelargonium leaves, and were found to be induced by GA3 in pelargonium cutting leaves under normal growth conditions.Darkening of pelargonium cutting increased expression of at least o­ne gene, which its expression subsided during the dark treatment.Gibberellic acid (GA3) treatment either before or at the third day of the dark period increased the expression of PeGAST-like gene, while o­n the forth day it had o­nly a marginal effect o­n PeGAST expression.We suggest that up-regulation of PeGAST like genes protect the tissue against accumulation of ROS possibly in the cell wall.Overexpression of these genes by GA3 treatment is probably o­ne of GA3 mechanisms that protect pelargonium cuttings against dark-induced senescence.