Long terminal repeats (LTR) and transcription factors regulate PHRE1 and PHRE2 activity in Moso bamboo under heat stress

Abstract

Background LTR retrotransposons play a significant role in plant growth, genome evolution, and environmental stress response, but their regulatory response to heat stress remains unclear. We have investigated the activities of two LTR retrotransposons, PHRE1 and PHRE2, of moso bamboo (Phyllostachys edulis) in response to heat stress. Results The differential overexpression of PHRE1 and PHRE2 with or without CaMV35s promoter showed enhanced expression under heat stress in transgenic plants. The transcriptional activity studies showed an increase in transposition activity and copy number among moso bamboo wild type and Arabidopsis transgenic plants under heat stress. Comparison of promoter activity in transgenic plants indicated that 5’LTR promoter activity was higher than CaMV35s promoter. Additionally, yeast one-hybrid (Y1H) system and in planta biomolecular fluorescence complementation (BiFC) assay revealed interactions of heat-dependent transcription factors (TFs) with 5’LTR sequence and direct interactions of TFs with pol and gag. Conclusions Our results conclude that the 5’LTR acts as a promoter and could regulate the LTR retrotransposons in moso bamboo under heat stress.

Retrotransposons: How the continuous evolutionary front shapes plant genomes for response to heat stress

“…Moreover, heat-activated LTR retrotransposons play a crucial role in shaping a genome over an evolutionary period (Wessler, 1996;Masuta et al, 2018). Recently, we reported that the role of two LTR retrotransposons, PHRE1 and PHRE2 (Ty3/Gypsy), in Moso bamboo (Phyllostachys edulis) indicated that the 5' LTR acts as a promoter and can increase transposition activity during heat stress (Papolu et al, 2021).…”

“…Carbon nanotubes have been used to perform stable genetic transformation in bacterial (Castillo et al, 2021;Weise et al, 2022) and mammalian (Golestanipour et al, 2018) cells. In our recent study, we used for the first time an efficient polyethylenimine (PEI)-walled carbon nanotube (SWNT) diffusion method to introduce the LTR retrotransposon plasmid DNA into Moso bamboo plants without transgene integration (Papolu et al, 2021) (Figure 2). We found that internalization of nanoparticles in the intact plant cells resulted in increased GFP expression in the leaves after 72 hours.…”

Stress-responsive retrotransposable elements in conifers

“…2). The following four LTR-RTs were also included: IFG7 of Monterey pine (P. radiata); PHRE1 and PHRE2 of Moso Bamboo (Phyllostachys edulis), which are actively transposed by heat (Papolu et al, 2021); and a well-known heat-activated retrotransposon (ONSEN) (Ito et al, 2011(Ito et al, , 2013Cao et al, 2015;Masuta et al, 2018). IFG7 is a member of the IFG family, which is abundant in conifer genomes and has an ancient origin.…”

“…The representative RTs were obtained from the GyDB database (Llorens et al, 2011), except for the sequences of Cereba (AY040832.1) and Opie-2 (U68408.1), which were retrieved from the NCBI nucleotide database. The sequences of PHRE1 and PHRE2 were obtained from Supplementary Table 1 of Papolu et al (2021). The sequence of ONSEN (AT1G11265) was retrieved from The Arabidopsis Information Resource.…”

The power of retrotransposons in high-throughput genotyping and sequencing

“…Numerous studies have investigated the activities of LTR retrotransposons under stress conditions ( Grandbastien, 1998 ; Pecinka et al., 2010 ; Tittel-Elmer et al., 2010 ; Ito et al., 2011 ; Butelli et al., 2012 ; Gaubert et al., 2017 ; Benoit et al., 2019 ; Cho et al., 2019 ; Papolu et al., 2021 ; Ramakrishnan et al., 2022 ). Mobile elements and endogenous retroviruses are important in the distribution of cis-regulatory elements, which contribute to genetic control in both the short (accumulation of hidden variability and processes of selection) and the long (adaptation and separation) term.…”