Transcriptomic Profiling and Physiological Responses of Halophyte Kochia sieversiana Provide Insights into Salt Tolerance

Abstract

Halophytes are remarkable plants that can tolerate extremely high-salinity conditions, and have different salinity tolerance mechanisms from those of glycophytic plants. In this work, we investigated the mechanisms of salinity tolerance of an extreme halophyte, Kochia sieversiana (Pall.) C. A. M, using RNA sequencing and physiological tests. The results showed that moderate salinity stimulated the growth and water uptake of K. sieversiana and, even under 480-mM salinity condition, K. sieversiana maintained an extremely high water content. This high water content may be a specific adaptive strategy of K. sieversiana to high salinity. The physiological analysis indicated that increasing succulence and great accumulations of sodium, alanine, sucrose, and maltose may be favorable to the water uptake and osmotic regulation of K. sieversiana under high-salinity stress. Transcriptome data indicated that some aquaporin genes and potassium (K+) transporter genes may be important for water uptake and ion balance, respectively, while different members of those gene families were employed under low- and high-salinity stresses. In addition, several aquaporin genes were up-regulated in low- but not high-salinity stressed roots. The highly expressed aquaporin genes may allow low-salinity stressed K. sieversiana plants to uptake more water than control plants. The leaf K+/root K+ ratio was enhanced under low- but not high-salinity stress, which suggested that low salinity might promote K+ transport from the roots to the shoots. Hence, we speculated that low salinity might allow K. sieversiana to uptake more water and transport more K+ from roots to shoots, increasing the growth rate of K. sieversiana.

De novo transcriptome sequencing and analysis of genes related to salt stress response in Glehnia littoralis

“…Comparative transcriptome analyses have previously been reported for a few halophytes, such as Halogeton glomeratus ( Yao et al, 2018 ; Wang et al, 2015 ), Iris lactea var. chinensis ( Gu et al, 2018 ), Kochia sieversiana ( Zhao et al, 2017 ), Nitraria sibirica Pall. ( Li et al, 2017a ), Suaeda maritima ( Gharat et al, 2016 ), Sporobolus virginicus ( Yamamoto et al, 2015 ), and Mesembryanthemum crystallinum ( Oh et al, 2015 ).…”

Beyond the greenhouse: coupling environmental and salt stress response reveals unexpected global transcriptional regulatory networks inSalicornia bigelovii

“…Kochia sieversiana can subsist at high salinity, most AQP genes were significantly up-regulated in 419 low, but not high salinity stressed roots (Zhao et al, 2017). In contrast, the halophyte Schrenkiella 420 parvula expressed a high number of AQPs for tolerance to salt toxicity with TIP2 being highly 421 expressed in S. parvula root as compared to shoot tissues (Loqué et al, 2005;Oh et al, 2014).…”

Recent Advances on Cellular Signaling Paradigm and Salt Stress Responsive Genes in Halophytes

“…AlHKT2;1 transcript level was found to be upregulated in the shoot at 12 and 24 h, while significant transcript abundance was recorded during K + starvation in the roots (Sanadhya et al 2015). Zhao et al (2017) reported the four HKT gene members in a halophytic grass Kochia sieversiana, where no significant transcript abundance was observed for HKT genes under the salt stress (Zhao et al 2017).…”

“…The major non-enzymatic action consists of ascorbate, glutathione, carotenoids, and tocopherol antioxidants (Nikalje et al 2017). There are many reports available on the characterization of halophyte antioxidant enzymes and their roles in ROS scavenging (Muchate et al 2016;Zhao et al 2017). In Sesuvium portulacastrum, physio-biochemical analysis of a facultative halophyte was maintained with the help of antioxidant enzyme activity (CAT, GR, SOD, APX, and GPX) under the salt stress (Muchate et al 2016).…”

“…In Sesuvium portulacastrum, physio-biochemical analysis of a facultative halophyte was maintained with the help of antioxidant enzyme activity (CAT, GR, SOD, APX, and GPX) under the salt stress (Muchate et al 2016). However, most of the transcript and RNA-Seq analysis reported the upregulation of antioxidant enzymes in salt stress (Zhao et al 2017).…”