Transcriptome Profiling of Haloxylon persicum (Bunge ex Boiss and Buhse) an Endangered Plant Species under PEG-Induced Drought Stress

Abstract

Haloxylon persicum is an endangered western Asiatic desert plant species, which survives under extreme environmental conditions. In this study, we focused on transcriptome analysis of H. persicum to understand the molecular mechanisms associated with drought tolerance. Two different periods of polyethylene glycol (PEG)-induced drought stress (48 h and 72 h) were imposed on H. persicum under in vitro conditions, which resulted in 18 million reads, subsequently assembled by de novo method with more than 8000 transcripts in each treatment. The N50 values were 1437, 1467, and 1524 for the control sample, 48 h samples, and 72 h samples, respectively. The gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis resulted in enrichment of mitogen-activated protein kinase (MAPK) and plant hormone signal transduction pathways under PEG-induced drought conditions. The differential gene expression analysis (DGEs) revealed significant changes in the expression pattern between the control and the treated samples. The KEGG analysis resulted in mapping transcripts with 138 different pathways reported in plants. The differential expression of drought-responsive transcription factors depicts the possible signaling cascades involved in drought tolerance. The present study provides greater insight into the fundamental transcriptome reprogramming of desert plants under drought.

Characterization of the gene expression profile response to drought stress in Haloxylon using PacBio single-molecule real-time and Illumina sequencing

“…Drought is one of the main environmental factors that restrict the survival, secondary metabolism, and productivity of plant species ( Li et al, 2021 ). Under drought stress, plants undergo several changes, which eventually lead to the reduction in gas exchange and photosynthesis and a decrease in cell division and cell expansion due to reduced enzyme activities and energy deficiency ( Thayale Purayil et al, 2020 ). To adapt to these conditions, plants employ a series of morphological, physiological, biochemical and molecular mechanisms, such as growth restriction ( Gupta et al, 2020 ), reactive oxygen species (ROS) scavenging ( Zhang et al, 2022 ) and transcriptional activation ( Zhu, 2016 ).…”

“…To adapt to these conditions, plants employ a series of morphological, physiological, biochemical and molecular mechanisms, such as growth restriction ( Gupta et al, 2020 ), reactive oxygen species (ROS) scavenging ( Zhang et al, 2022 ) and transcriptional activation ( Zhu, 2016 ). Functional proteins and regulatory proteins are two major categories of stress-inducible proteins that play an important role in plant adaptation to stress ( Thayale Purayil et al, 2020 ). Regulatory proteins are involved in the regulation of downstream genes in stress response pathways.…”

“…The role of MAPK signaling cascades in abiotic stresses such as drought, salt stress, high temperature and low temperature stress has been elucidated in different plants ( Bigeard and Hirt, 2018 ). Under drought conditions, the phosphorylation of target genes is regulated by MAPK, which controls the activities of different structural proteins and various TFs involved in abiotic stress tolerance ( Thayale Purayil et al, 2020 ). Together with TFs, MAPK signaling cascades play important roles in ABA-dependent and ABA-independent plant abiotic stress responses ( Mahmood et al, 2019 ).…”

“…Molecular mechanisms to drought stress have been extensively studied in broad-leaved species such as Populus nigra ( Yildirim and Kaya, 2017 ), Betula platyphylla ( Li H. Y. et al, 2020 ), and Morus spp. ( Sun et al, 2020 ), but only a few studies have focused on Haloxylon ammodendron ( Long et al, 2014 ; Fan et al, 2018 ) and Haloxylon persicum ( Thayale Purayil et al, 2020 ). Therefore, it is important to understand the drought tolerance of H. ammodendron and H. persicum .…”

“…They often form large-area pure stands in desert regions and have the function of fixing dunes. As xerophytic desert trees, these species have the characteristics of resistance to drought, high temperatures, saline alkali soils, wind erosion, and cold ( Long et al, 2014 ; Thayale Purayil et al, 2020 ). The genus is widely distributed in desert and semi-desert areas, and the plants have ecological benefits.…”