期刊
FRONTIERS IN PLANT SCIENCE
卷 10, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fpls.2019.00046
关键词
Brassica napus L.; nitrogen remobilization efficiency; senescence; protease activity; regulation; phytohormones
资金
- French National Research Agency [ANR-11-BTBR-004]
- French Ministry of Research
- Ph.D. Doctoral School (EDNBISE, Ecole Doctorale Normande Biologie Integrative, Sante, Environnement)
- ERA-IB project PRODuCE
- Max Planck Society
- COST [CM1004]
- University of Oxford
Oilseed rape (Brassica napus L.) is an oleoproteaginous crop characterized by low N use efficiency (NUE) that is mainly related to a weak Nitrogen Remobilization Efficiency (NRE) during the sequential leaf senescence of the vegetative stages. Based on the hypothesis that proteolysis efficiency is crucial for the improvement of leafNRE, our objective was to characterize key senescence-associated proteolytic mechanisms of two genotypes (Tenor and Samourai) previously identified with contrasting NREs. To reach this goal, biochemical changes, protease activities and phytohormone patterns were studied in mature leaves undergoing senescence in two genotypes with contrasting NRE cultivated in a greenhouse under limiting or ample nitrate supply. The genotype with the higher NRE (Tenor) possessed enhanced senescence processes in response to nitrate limitation, and this led to greater degradation of soluble proteins compared to the other genotype (Samourai). This efficient proteolysis is associated with (i) an increase in serine and cysteine protease (CP) activities and (ii) the appearance of new CP activities (RD21-like, SAG12-like, RD19-like, cathepsin-B, XBCP3-like and aleurain-like proteases) during senescence induced by N limitation. Compared to Samourai, Tenor has a higher hormonal ratio ([salicylic acid] + [abscisic acid])/([cytokinins]) that promotes senescence, particularly under low N conditions, and this is correlated with the stronger protein degradation and serine/CP activities observed during senescence. Short statement: The improvement in N recycling during leaf senescence in a genotype of Brassica napus L. characterized by a high nitrogen remobilization efficiency is related to a high phytohormonal ratio ([salicylic acid] + [abscisic acid])/([cytokinins]) that promotes leaf senescence and is correlated with an increase or the induction of specific serine and cysteine protease activities.
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