How does nitrate regulate plant senescence?

Effects of Melatonin on Morphological Characteristics, Mineral Nutrition, Nitrogen Metabolism, and Energy Status in Alfalfa Under High-Nitrate Stress

“…Ion uptake and compartmentalization are vitally important not only for improving normal growth but also for sustaining plant performance under high-salinity conditions because such adversity disturbs ion homeostasis (Adams et al, 1992 ). Excessive nitrogen is harmful to plants, even though nitrogen is essential for growth, development and metabolisms (Hao et al, 2015 , 2017 ; Zhang R. et al, 2017 ; Wen et al, 2020 ). When nitrogen uptake exceeds plant assimilation capacity, plants will accumulate excessive -N and -N, which will lead to soil secondary salinization and plant salt toxicity, thus affecting growth and development (Britto and Kronzucker, 2002 ; Roosta and Schjoerring, 2007 ; Zhang R. et al, 2017 ).…”

“…As the most productive and highest quality forage crop, alfalfa can be used for grazing, silage, hay, and even human fresh food and health products (Tang et al, 2013 ; Jaime et al, 2019 ; Lin et al, 2020 ). Nitrogen is a component of amino acids, nucleic acids, proteins, nucleoproteins, chlorophyll, enzymes, hormones and secondary metabolites, as well as the basis of key genetic materials (Wen et al, 2020 ). Hence, the efficiency and availability of nitrogen have decisive influences on the growth, development, and metabolisms of plants (Hachiya and Sakakibara, 2017 ).…”

“… -N is the most prevalent in soil for the growth and morphological construction of most plants (Oldroyd and Leyser, 2020 ; Wen et al, 2020 ). However, in the alfalfa-growing areas with a dry climate and alkaline soil, soil nitrification is serious but denitrification is weak, and excess -N is easy to accumulate in the soil (Ju et al, 2011 ).…”

“…It has demonstrated that excessive -N reduces photosynthesis and enzyme activities, and increases ionic toxicity, osmotic stress and reactive oxygen species (ROS), further affecting crop quality and yields (Yang et al, 2010 ; Zhang R. et al, 2017 ). Nitrate absorption and transformation are mainly regulated by the nitrogen metabolism pathway in alfalfa, which is mainly modulated by nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH) (Zhang R. et al, 2017 ; Wen et al, 2020 ). In addition, plant growth and development are ultimately driven by light energy captured through photosynthesis, and the energy available state plays an important role in the metabolism of plants (De Col et al, 2017 ).…”

Photoperiodic Signaling and Senescence, an Ancient Solution to a Modern Problem?

“…programs, eventually leading to the death of the organism. However, despite its apparently deteriorating character, it is often a tightly controlled process whose main objective is to allow recycling, remobilization, and reassignment of nutrients from decaying tissues to developing organs (Wen et al, 2020). In plants with short life cycles, this recycling takes place in seeds or fruits, whereas in perennial plants, it mainly happens in storage organs such as stems or roots (Gan and Amasino, 1997;Lim et al, 2007).…”