Phenotypic Analysis and Molecular Markers of Leaf Senescence

Abstract

The process of leaf senescence consists of the final stage of leaf development. It has evolved as a mechanism to degrade macromolecules and micronutrients and remobilize them to other developing parts of the plant; hence it plays a central role for the survival of plants and crop production. During senescence, a range of physiological, morphological, cellular, and molecular events occur, which are generally referred to as the senescence syndrome that includes several hallmarks such as visible yellowing, loss of chlorophyll and water content, increase of ion leakage and cell death, deformation of chloroplast and cell structure, as well as the upregulation of thousands of so-called senescence-associated genes (SAGs) and downregulation of photosynthesis-associated genes (PAGs). This chapter is devoted to methods characterizing the onset and progression of leaf senescence at the morphological, physiological, cellular, and molecular levels. Leaf senescence normally progresses in an age-dependent manner but is also induced prematurely by a variety of environmental stresses in plants. Focused on the hallmarks of the senescence syndrome, a series of protocols is described to asses quantitatively the senescence process caused by developmental cues or environmental perturbations. We first briefly describe the senescence process, the events associated with the senescence syndrome, and the theories and methods to phenotype senescence. Detailed protocols for monitoring senescence in planta and in vitro, using the whole plant and the detached leaf, respectively, are presented. For convenience, most of the protocols use the model plant species Arabidopsis and rice, but they can be easily extended to other plants.

Copper deficiency alters shoot architecture and reduces fertility of both gynoecium and androecium in Arabidopsis thaliana

“…WRKY53 is a master regulator of age-induced leaf senescence that is associated with the onset of natural senescence and acts upstream in the senescence transcriptional cascade (Zentgraf et al, 2010). Both SAG12 and SAG13 are downstream WRKY53 targets with SAG12 considered a marker for age-dependent natural senescence while SAG13 is commonly used to evaluate stress-induced senescence (Zhao et al, 2018).…”

Characterization of Somatic Embryogenesis Receptor-Like Kinase 4 as a Negative Regulator of Leaf Senescence in Arabidopsis

“…The chlorophyll content was quantified as described previously [35]. The fluorescence in leaves was measured with a chlorophyll fluorometer (Opti-Sciences, Tyngsboro, MA, USA) according to the manufacturer’s instructions.…”

“…The samples were then boiled for 15 min and then the second conductivity was measured. The percentage of the first measurement over the second measurement was used as the membrane leakage indicator [35]. These assay results were retrieved from five independent biological repeats.…”

The secret of H2S to keep plants young and fresh and its products

“…Moreover, under abiotic and biotic stresses, senescence is also a good exit strategy for plants that guarantees their best chance of survival (Bresson et al 2018). During senescence, plants experience a series of metabolic, cellular, physiological and molecular changes, and thus, senescence is closely related to ripening and abscission processes (Bleecker & Patterson 1997;Gan 2018;Zhao et al 2018). Morphologically, the most prominent phenotypes associated with senescence are changes in the colour and texture of leaves and fruits, as well as the vulnerability of the senescing tissues to pathogen attack (Zhao et al 2018).…”