A Genotypic Comparison Reveals That the Improvement in Nitrogen Remobilization Efficiency in Oilseed Rape Leaves Is Related to Specific Patterns of Senescence-Associated Protease Activities and Phytohormones.

摘要: Oilseed rape (Brassica napus L.) is an oleoproteaginous crop characterized by low N use efficiency (NUE) that mainly related to a weak Nitrogen Remobilization Efficiency (NRE) during the sequential leaf senescence of vegetative stages. Based on hypothesis proteolysis crucial for improvement leafNRE, our objective was characterize key senescence-associated proteolytic mechanisms two genotypes (Tenor and Samourai) previously identified with contrasting NREs. To reach this goal, biochemical changes, protease activities phytohormone patterns were studied in mature leaves undergoing NRE cultivated greenhouse under limiting or ample nitrate supply. The genotype higher (Tenor) possessed enhanced processes response limitation, led greater degradation soluble proteins compared other (Samourai). This efficient associated (i) increase serine cysteine (CP) (ii) appearance new CP (RD21-like, SAG12-like, RD19-like, cathepsin-B, XBCP3-like aleurain-like proteases) induced limitation. Compared Samourai, Tenor has hormonal ratio ([salicylic acid] + [abscisic acid])/([cytokinins]) promotes senescence, particularly conditions, correlated stronger protein serine/CP observed senescence. Short statement: recycling Brassica L. high nitrogen remobilization phytohormonal induction specific activities.