Abstract
Haloxylon ammodendron, a perennial xero-halophyte, is an essential species for investigating the effects of drought on desert tree. To gain a comprehensive knowledge on the responses of H. ammodendron to drought stress, we specially performed the molecular and physiological analysis of H. ammodendron in response to −0.75 MPa osmotic stress for six and 24 h in lab condition via RNA-seq and digital gene expression (DGE). In total, 87,109 unigenes with a mean length of 680 bp and 13,486 potential simple sequence repeats (SSRs) were generated, and 3353 differentially expressed genes (DEGs) in shoots and 4564 in roots were identified under stress. These DEGs were mainly related to ion transporters, signal transduction, ROS-scavenging, photosynthesis, cell wall organization, membrane stabilization and hormones. Moreover, the physiological changes of inorganic ions and organic solute content, peroxidase (POD) activity and osmotic potential were in accordance with dynamic transcript profiles of the relevant genes. In this study, a detailed investigation of the pathways and candidate genes identified promote the research on the molecular mechanisms of abiotic stress tolerance in the xero-halophytic species. Our data provides valuable genetic resources for future improvement of forage and crop species for better adaptation to abiotic stresses.
Highlights
Drought is one of the major abiotic stresses affecting plant growth and development worldwide, leading to productivity reduction of approximately one third of earth’s arable land [1,2]
The research advances on H. ammodendron have mainly focused on its structural and physiological changes in response to drought stress: (1) H. ammodendron could absorb a large number of Na+ than K+ transported to photosynthesizing stems and leaves for osmotic adjustment under drought stress [12]; (2) 1.0% of the soil water was considered to be the “survival water threshold” of the growth [8]; (3) the application of Na or the combination usage of Na and Si led to enhancement of growth and drought tolerance of H. ammodendron [10]
In order to obtain a more complete understanding of the complex gene networks regulating physiological and biochemical processes for H. ammodendron adaptation to osmotic stress, we specially examined the gene expression dynamics of plants responding to drought and elucidated the potential molecular mechanisms involved in drought tolerance of H. ammodendron
Summary
Drought is one of the major abiotic stresses affecting plant growth and development worldwide, leading to productivity reduction of approximately one third of earth’s arable land [1,2]. Understanding the regulatory mechanism involved in stress responses and identifying stress-resistant genes in xerophytes are necessary to improve drought tolerance of crop plants using genetic engineering. The research advances on H. ammodendron have mainly focused on its structural and physiological changes in response to drought stress: (1) H. ammodendron could absorb a large number of Na+ than K+ transported to photosynthesizing stems and leaves for osmotic adjustment under drought stress [12]; (2) 1.0% of the soil water was considered to be the “survival water threshold” of the growth [8]; (3) the application of Na or the combination usage of Na and Si led to enhancement of growth and drought tolerance of H. ammodendron [10]. The physiological and molecular mechanism underlying how H. ammodendron adapt to dry environment is still unclear and the genome of H. ammodendron has not been sequenced up to now
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