Foliar senescence is a highly orchestrated phenomenon associated with de novo synthesis of proteolytic enzymes and antioxidants, dismantling of cellular contents and relocation of nutrients to storage organs (García-Plazaola et al. 2003, Gepstein 2004, Wojciechowska et al. 2018a, Woo et al. 2019, Figure 1). During senescence, a major fraction of mobile mineral nutrients, in particular, nitrogen (N), phosphorus and potassium, is resorbed from leaves to fuel the growth of new leaves and other plant parts (Killingbeck 1996, Franklin and Ågren 2002, Niinemets and Tamm 2005, Niinemets et al. 2012, Figure 1). A significant fraction of soluble carbon is also retranslocated from senescing leaves before leaf abscission (Chapin and Moilanen 1991, Norby et al. 2001, Niinemets and Tamm 2005). However, much less is known of root carbon and N resorption from senescing roots. Some studies have observed that nutrients are not resorbed from senescing roots (Gordon and Jackson 2000, Liu et al. 2019), while others have found that roots are capable of nutrient resorption (Kunkle et al. 2009, Freschet et al. 2010, Zadworny et al. 2015). As fine root turnover can account for 20–50% or even more of total annual plant carbon fixation (Finér et al. 2011, Müller-Haubold et al. 2013), and 10–60% of plant annual N flux is used for fine root production (Ruess et al. 1996, Magill et al. 2004, Aosaar et al. 2016, Mucha et al. 2020), gaining an insight into senescence of roots is of major significance for understanding tree carbon and nutrient relations.

中文翻译：

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树上和地下的植物器官衰老：如何最好地利用资源来促进新的生长？

叶面衰老是与蛋白水解酶和抗氧化剂的从头合成，细胞内含物的分解以及养分向存储器官的重新定位有关的高度精心策划的现象（García-Plazaola等人2003，Gepstein 2004，Wojciechowska等人2018 aWoo等。2019，图1）。在衰老过程中，大部分的移动性矿物质营养素，特别是氮（N），磷和钾，会从叶片中吸收，以促进新叶片和其他植物部分的生长（Killingbeck 1996，Franklin和Ågren2002，Niinemets和Tamm 2005年，Niinemets等人，2012年，图1）。大量的可溶性碳在叶片脱落之前也从衰老的叶片中重新迁移（Chapin和Moilanen 1991，Norby等2001，Niinemets和Tamm 2005）。但是，对于衰老的根部吸收碳和氮的了解还很少。一些研究已经观察到养分不会从衰老的根部吸收养分（Gordon和Jackson 2000，Liu等人，2019），而另一些研究发现根部能够吸收养分（Kunkle等人，2009； Freschet等人，2010； Zadworny）。等人，2015年）。