Senescence represents the final developmental act of the leaf, during which the leaf cell is dismantled in a coordinated manner to remobilize nutrients and to secure reproductive success. The process of senescence provides the plant with phenotypic plasticity to help it adapt to adverse environmental conditions. Here, we provide a comprehensive overview of the factors and mechanisms that contro...

Leaf senescence and associated changes in redox components were monitored in commercial pea (Pisum sativum L. cv. Phoenix) plants grown under different nitrogen regimes for 12 weeks until both nodules and leaves had fully senesced. One group of plants was inoculated with Rhizobium leguminosarum and grown with nutrient solution without nitrogen. A second group was not inoculated and these were g...

Aging in leaves is characterized by a decrease in chlorophyll content and an accompanying loss of protein and ribonucleic acid. It is well known that these symptoms of senescence occur at an accelerated rate in excised mature leaves and in leaf discs floated on water. In recent years it has been established that several chemical substances retard the senescence of leaves. Among the compounds wh...

To better understand the molecular mechanisms behind plant growth and leaf senescence in monocot plants, we identified a mutant exhibiting dwarfism and an early-senescence leaf phenotype, termed dwarf and early-senescence leaf1 (del1). Histological analysis showed that the abnormal growth was caused by a reduction in cell number. Further investigation revealed that the decline in cell number in...

Development was monitored throughout the entire life span of silver birch (Betula pendula Roth.) leaves. The focus was on senescence-related changes in photosynthesis and gene expression. The youngest fully developed leaves were compared with older senescing leaves in two silver birch lines: the wild-type line R and a late-senescing line R3.1. Line R3.1 was found among transgenic lines produced...

The dynamic assembly and disassembly of microtubules (MTs) is essential for cell function. Although leaf senescence is a well-documented process, the role of the MT cytoskeleton during senescence in plants remains unknown. Here, we show that both natural leaf senescence and senescence of individually darkened Arabidopsis (Arabidopsis thaliana) leaves are accompanied by early degradation of the ...

As the last stage of leaf development, senescence is a fine-tuned process regulated by interplays of multiple signaling pathways. We have previously identified soybean (Glycine max) SENESCENCE-ASSOCIATED RECEPTOR-LIKE KINASE (SARK), a leucine-rich repeat-receptor-like protein kinase from soybean, as a positive regulator of leaf senescence. Here, we report the elucidation of the molecular mechan...

Cytokinins are plant hormones with profound roles in growth and development, including control of leaf longevity. Although the cytokinin signal is known to be perceived by histidine kinase receptors, the underlying molecular mechanism and specificity of the receptors leading to delayed leaf senescence have not yet been elucidated. Here, we found that AHK3, one of the three cytokinin receptors i...

In plants, urea derives either from root uptake or protein degradation. Although large quantities of urea are released during senescence, urea is mainly seen as a short-lived nitrogen (N) catabolite serving urease-mediated hydrolysis to ammonium. Here, we investigated the roles of DUR3 and of urea in N remobilization. During natural leaf senescence urea concentrations and DUR3 transcript levels...