Na2CO3-responsive mechanisms in halophyte Puccinellia tenuiflora roots revealed by physiological and proteomic analyses

Abstract

Soil alkalization severely affects crop growth and agricultural productivity. Alkali salts impose ionic, osmotic, and high pH stresses on plants. The alkali tolerance molecular mechanism in roots from halophyte Puccinellia tenuiflora is still unclear. Here, the changes associated with Na2CO3 tolerance in P. tenuiflora roots were assessed using physiological and iTRAQ-based quantitative proteomic analyses. We set up the first protein dataset in P. tenuiflora roots containing 2,671 non-redundant proteins. Our results showed that Na2CO3 slightly inhibited root growth, caused ROS accumulation, cell membrane damage, and ion imbalance, as well as reduction of transport and protein synthesis/turnover. The Na2CO3-responsive patterns of 72 proteins highlighted specific signaling and metabolic pathways in roots. Ca2+ signaling was activated to transmit alkali stress signals as inferred by the accumulation of calcium-binding proteins. Additionally, the activities of peroxidase and glutathione peroxidase, and the peroxiredoxin abundance were increased for ROS scavenging. Furthermore, ion toxicity was relieved through Na+ influx restriction and compartmentalization, and osmotic homeostasis reestablishment due to glycine betaine accumulation. Importantly, two transcription factors were increased for regulating specific alkali-responsive gene expression. Carbohydrate metabolism-related enzymes were increased for providing energy and carbon skeletons for cellular metabolism. All these provide new insights into alkali-tolerant mechanisms in roots.

Elongation of barley roots in high‐pH nutrient solution is supported by both cell proliferation and differentiation in the root apex

“…The suppression of root elongation in tomato cultured in pH 8 solution could result from the intentional growth suppression by the tomato itself. The effects of external pH on signalling in root growth regulation have been recently reported (Graças et al 2016;Zhao et al 2016). Further studies are needed to investigate the transmission of high-pH stress from the rhizosphere to shoots followed by systemic regulation of growth.…”

Na2CO3-Responsive Photosynthetic and ROS Scavenging Mechanisms in Chloroplasts of Alkaligrass Revealed by Phosphoproteomics

“…S hoot length and leaf fresh weight of seedlings were immediately measured. Dry weight, relative water content, as well as ion contents of K + , Na + , Ca 2+ and Mg 2+ were determined according to the method of Zhao et al [26].…”

“…The malondialdehyde content and relative electrolyte leakage were determined using previous methods [68,69]. Free proline and total soluble sugar contents were quantified with a spectrometer at 520 nm and 630 nm, respectively [26]. The content of endogenous ABA was measured by an indirect ELISA method [70].…”

“…It has strong ability to survive in extreme saline-alkali soil (pH range of 9-10). Several salinity-/alkali-responsive genes and/or proteins in leaves and roots of alkaligrass have been reported [24-26]. A previous transcriptomic study also revealed that a number of Na 2 CO 3 responsive genes were overrepresented in metabolism, signal transduction, transcription, and cell rescue [27].…”

A Na2CO3-responsive chitinase gene fromChinese wildryeimprove pathogen resistance and saline-alkali stress tolerance in transgenic tobacco and maize

“…The changed cellulose content may regulate cross-linking and rigidity of the 475 cell wall, which acts as a barrier for salt entrance or pathogen invasion. 476 Although a large number of alkali-responsive genes were reported from different plants, 477 a few have been cloned and characterized (Zhao et al, 2016). Overexpression of the 478 alkali-stress-inducable RMtATP6 and NADP-ME 2 in rice and Arabidopsis enhanced the 479 tolerance against osmotic, NaCl and Na 2 CO 3 stresses (Liu et al, 2007;Zhang et al, 2006 (Kobayashi et al, 2012).…”