Investigation of the role of senescence-associated receptor- like kinase (AtSARK) under salinity stress
Soil salinity has an impact on plant development that may result in their precocious and objectionable senescence. The problem of salinization of soils is actual in modern age, since 77 million hectares out of 1.5 billion hectares of cultivable land in the world is considered as saline soil (Miransari, 2017), therefore they are ineligible for agronomical purposes. In fact, soil salinity is an issue for Kazakhstan, because 40 percent of its area is salinized by chloride, sulfate and sodium salts (Isanova et al., 2019). High salinity level damages the plants by impeding the aqueous balance in and out of the plant cells (Chhabra, 1996), thereby increasing the plant senescence (Ghanem et al., 2008). This sequence of events will negatively affect the agriculture, therefore it is necessary to study the ways by which it is possible to ameliorate the stress resistance of plants, which is in our case to investigate the molecular mechanisms behind the plant senescence that involves senescence-associated genes. The plant senescence is well-regulated destructive process that determines the final developmental phase in plants, which can be either induced by stress or age (Woo, Masclaux-Daubresse & Lim, 2018). This stage is accompanied with changes in leaf color due to chlorophyll degradation, in cellular integrity and in metabolism (Rasool et al., 2019). To be more specific, senescence causes the decreased antioxidant enzyme activity, which results in elevated accumulation of ROS molecules at some distinctive time points, and breakdown of essential macromolecules, such as nucleic acids, proteins and lipids (Woo, Masclaux-Daubresse & Lim, 2018). The exact mechanism that explains how and when plant cells resolve to start senescence process is still unknown (Woo, Masclaux-Daubresse & Lim, 2018); however, studying the senescence associated genes will be essential to create transgenic plants with high tolerance against multiple abiotic stresses, including salinity stress. The senescence-associated receptor-like kinase, or SARK, is considered as one of the not completely investigated leucine-rich repeat containing receptor-like molecule (Xiao et al., 2015). It is known to be involved in the positive regulation of the plant senescence process through the auxin and ethylene biosynthesis, which is mainly responsible for the general plant development (Xu et al., 2011). The category of leucine-reach repeats receptor-like kinases possess the essential role in responding of plant cells to stressful stimuli (Xu et al., 2011). In addition, it was demonstrated that premature senescence (age dependent) and abnormal development of model plant Arabidopsis thaliana was resulted due to the overexpression of SARK gene; however, it was no evidence of involvement of SARK in stress induced senescence (Xu et al., 2011). So, our study will focus on the investigation of the role of SARK gene in salinity stress caused plant senescence by application of biochemical and molecular methods on wild-type (Col ecotype) and Atsark mutant samples of Arabidopsis thaliana plant.