Biology subjects

Alallaq, S.

Publications and source records attributed to Alallaq, S..

3 recordsLinked to original sources

bioRxiv2021

Molecular basis of differential adventitious rooting competence in poplar genotypes

O_LIRecalcitrant adventitious root (AR) development is a major hurdle in propagating commercially important woody plants. Although significant progress has been made to identify genes involved in subsequent steps of AR development, the molecular basis of differences in apparent recalcitrance to form AR between easy-to-root and difficult-to-root genotypes remains unknown. C_LIO_LITo address this, we generated cambium tissue-specific transcriptomic data from stem cuttings of hybrid aspen, T89 (difficult-to-root) and hybrid poplar OP42 (easy-to-root) and used transgenic approaches to verify the role of several transcription factors (TF) in the control of adventitious rooting. C_LIO_LIIncreased peroxidase activity is positively correlated with better rooting. We found differentially expressed genes encoding Reactive Oxygen Species (ROS) scavenging proteins to be enriched in OP42 compared to T89. A higher number of differentially expressed TF in OP42 compared to T89 cambium cells was revealed by a more intense transcriptional reprograming in the former. PtMYC2, a potential negative regulator, was less expressed in OP42 compared to T89. Using transgenic approaches, we have demonstrated that PttARF17.1 and PttMYC2.1 negatively regulate adventitious rooting. C_LIO_LIOur results provide insights into the molecular basis of genotypic differences in AR and implicate differential expression of the master regulator MYC2 as a critical player in this process. C_LI

plant biology↗

bioRxiv2020

Light controls de novo adventitious root regeneration by modulating jasmonate and cytokinin homeostasis in Norway spruce hypocotyls

Vegetative propagation relies on the capacity of plants to regenerate de novo adventitious roots (ARs), a quantitative trait controlled by the interaction of endogenous factors such as hormones and environmental cues among which light plays a central role. However, the physiological and molecular components mediating light cues during AR initiation (ARI) remain largely elusive. We explored the effect of light spectral quality on ARI in de-rooted Norway spruce seedlings as well as on hormone metabolism with sensitive mass spectrometry-based methods. We coupled this to gene expression analysis to identify potential signaling pathways and to extensive anatomical characterization to investigate ARI at the cellular level. We showed that in contrast to white light and blue light, red light promoted ARI likely by reducing jasmonate (JA) and JA-isoleucine biosynthesis and repressing the accumulation of isopentyl-adenine-type cytokinins and abscisic acid. We confirmed that exogenously applied JA and/or CK inhibit ARI, and found that they possibly act in the same pathway. The negative effect of JA was confirmed at the histological level. We showed that JA represses the early events of ARI. In conclusion, RL promotes ARI by repressing the accumulation of the wound-induced phytohormones JA and CK. HighlightBlue and red light have an opposite effect on adventitious root initiation in Norway spruce hypocotyl, red light having a promoting effect by modulating hormone homeostasis.

plant biology↗

bioRxiv2019

Cytokinin induction by the Jasmonate-induced AP2/ERF115 represses adventitious rooting in Arabidopsis

Jasmonate (JA), an oxylipin-derived phytohormone, plays crucial roles not only in plant immunity and defense against herbivorous insects but also in plant growth and developmental processes, including regeneration and organogenesis. However, the mechanistic basis of its mode of action and precise role in integrating other signaling cues are poorly understood. Here we provide genetic evidences that JA signaling acts in both NINJA-dependent and -independent modulation of the transcriptional activity of MYC transcription factors involved in the inhibition of adventitious root initiation (ARI). Our data show that NINJA-dependent JA signaling in pericycle cells blocks early events of ARI. Moreover, transcriptomic comparison of ninja-1myc2-322B double mutant (which produce extremely few ARs) and wild type seedlings identified a novel molecular network governed by the APETALA2/ETHYLENE RESPONSE FACTOR 115 (ERF115) transcription factor. We demonstrate that JA-induced ERF115 activates the cytokinin signaling machinery and thereby represses ARI. Altogether, our results reveal a molecular network involving cooperative crosstalk between JA and CK machineries that inhibits ARI.

plant biology↗