Transcriptomics analysis of salt stress tolerance in the roots of the mangrove Avicennia officinalis

Abstract

Salinity affects growth and development of plants, but mangroves exhibit exceptional salt tolerance. With direct exposure to salinity, mangrove roots possess specific adaptations to tolerate salt stress. Therefore, studying the early effects of salt on mangrove roots can help us better understand the tolerance mechanisms. Using two-month-old greenhouse-grown seedlings of the mangrove tree Avicennia officinalis subjected to NaCl treatment, we profiled gene expression changes in the roots by RNA-sequencing. Of the 6547 genes that were differentially regulated in response to salt treatment, 1404 and 5213 genes were significantly up- and down-regulated, respectively. By comparative genomics, 93 key salt tolerance-related genes were identified of which 47 were up-regulated. Upon placing all the differentially expressed genes (DEG) in known signaling pathways, it was evident that most of the DEGs involved in ethylene and auxin signaling were up-regulated while those involved in ABA signaling were down-regulated. These results imply that ABA-independent signaling pathways also play a major role in salt tolerance of A. officinalis. Further, ethylene response factors (ERFs) were abundantly expressed upon salt treatment and the Arabidopsis mutant aterf115, a homolog of AoERF114 is characterized. Overall, our results would help in understanding the possible molecular mechanism underlying salt tolerance in plants.

Molecular responses to freshwater limitation in the mangrove tree Avicennia germinans (Acanthaceae)

“…Mangroves have aerial, photosynthesizing roots, which contribute to carbon gain and enable root respiration in anaerobic soils, using both atmospheric and photosynthetically regenerated oxygen (Kitaya et al, 2002). Therefore, although various photosynthesis genes frequently express only in basal levels in roots of the model plant, Arabidopsis thaliana (Klepikova, Kasianov, Gerasimov, Logacheva, & Penin, 2016), they may express in higher levels in mangroves, even during the seedling stage, when aerial roots are generally absent, as observed in A. germinans , and in the congeneric A. officinalis (Krishnamurthy et al, 2017). Differential transcripts expression analyses revealed that photosynthesis-associated transcripts were enriched, mainly in roots and stems from the DET-Arid set.…”

Foreign cry1Ac gene integration and endogenous borer stress-related genes synergistically improve insect resistance in sugarcane

“…Microarrays, serial analysis of gene expression and RNA sequencing (RNA-Seq) are the three most commonly used methods for transcriptome analysis in gene expression studies [28, 29]. RNA-Seq, which allows for the near-complete characterization of transcriptomic events occurring in a specific tissue at a certain time, has been widely applied and proven particularly useful in non-model plants, including sugarcane [28, 30–32]. For transgenic plants, a number of studies to date have used transcriptome analysis to study gene expression or assess the impact of genetic engineering [29, 33–36].…”

AtCIPK16 Mediates Salt Stress Through Phytohormones and Transcription Factors

“…Rapid adjustment to new conditions may explain the high salinity tolerance of halophytes, such as mangroves, and this may be an important mechanism for improved salt tolerance (Krishnamurthy et al 2017;Liang et al 2012;Zhu 2001). Secondly, the rapid onset of the initial osmotic adjustments to counteract the immediate reduction in plant growth due to salinity stress, requires instant rootto-shoot signalling once salt has been detected at the roots (Batistič and Kudla 2010;Gilroy et al 2014;Roy et al 2014;Roy et al 2011;Shabala et al 2016).…”