Biology subjects

De Rybel, B.

Publications and source records attributed to De Rybel, B..

4 recordsLinked to original sources

bioRxiv2018

RCD1 Coordinates Chloroplastic and Mitochondrial Electron Transfer through Interaction with ANAC Transcription Factors

Signaling from chloroplasts and mitochondria, both dependent on reactive oxygen species (ROS), merge at the nuclear protein RADICAL-INDUCED CELL DEATH1 (RCD1). ROS produced in the chloroplasts affect the abundance, thiol redox state and oligomerization of RCD1. RCD1 directly interacts in vivo with ANAC013 and ANAC017 transcription factors, which are the mediators of the ROS-related mitochondrial complex III retrograde signa and suppresses activity of ANAC013 and ANAC017. Inactivation of RCD1 leads to increased expression of ANAC013 and ANAC017-regulated genes belonging to the mitochondrial dysfunction stimulon (MDS), including genes for mitochondrial alternative oxidases (AOXs). Accumulating AOXs and other MDS gene products alter electron transfer pathways in the chloroplasts, leading to diminished production of chloroplastic ROS and increased protection of photosynthetic apparatus from ROS damage. RCD1-dependent regulation affects chloroplastic and mitochondrial retrograde signaling including chloroplast signaling by 3-phosphoadenosine 5-phosphate (PAP). Sensitivity of RCD1 to organellar ROS provides feedback control of nuclear gene expression.

plant biology↗

bioRxiv2018

OsIQD14 regulates rice grain shape through modulating the microtubule cytoskeleton

Cortical microtubule (MT) arrays play a critical role in plant cell shape determination by defining the direction of cell expansion1-3. The control of plant organ shape and architecture is a major target of cereal crop improvement. Given the pleiotropic effects of MT modification, however, it is challenging to exploiting MT array organization for crop improvement. Moreover, as plants continuously adapt cell growth and expansion to ever-changing environmental conditions, multiple environmental (e.g. light4) and developmental (e.g. hormones5,6) inputs need to be translated into changes of the MT cytoskeleton. Here, we identify and functionally characterize an auxin-inducible and MT-localized protein OsIQ67-DOMAIN14 (OsIQD14), which is highly expressed in rice seed hull cells. While deficiency of OsIQD14 results in short and wide seeds and increases overall yield, overexpression leads to narrow and long seeds, caused by changes in the direction of MT arrangement. We further show that OsIQD14-mediated MT reordering is regulated through interacting with SPIRAL2, a MT-binding protein involved in KATANIN1-mediated MT rearrangement7,8, and with calmodulin proteins. As such, OsIQD14 acts as an integrator of auxin and calcium inputs into MT rearrangements, and allows effective local cell shape manipulation to improve a key rice yield trait.

plant biology↗

bioRxiv2018

IQD proteins integrate auxin and calcium signaling to regulate microtubule dynamics during Arabidopsis development

Geometry and growth and division direction of individual cells are major contributors to plant organ shape and these processes are dependent on dynamics of microtubules (MT). Different MT structures, like the cortical microtubules, preprophase band and mitotic spindle, are characterized by diverse architectural dynamics (Hashimoto, 2015). While several MT binding proteins have been identified that have various effects on MT stability and architecture, they do not discriminate between the different MT structures. It is therefore likely that specific MT binding proteins exist that differentiate between MT structures in order to allow for the differences in architectural dynamics. Although evidence for the effect of specific cues, such as light and auxin, on MT dynamics has been shown in recent years (Lindeboom et al., 2013; Chen et al., 2014), it remains unknown how such cues are integrated and lead to specific effects. Here we provide evidence for how auxin and calcium signaling can be integrated to modulate MT dynamics, by means of IQD proteins. We show that the Arabidopsis IQD15-18 subclade of this family is regulated by auxin signaling, can bind calmodulins in a calcium-dependent manner and are evolutionarily conserved. Furthermore, AtIQD15-18 directly bind SPIRAL2 protein in vitro and in vivo and modulate its function, likely in a calmodulin-dependent way, thereby providing a missing link between two important regulatory pathways of MT dynamics.\n\nOne sentence summaryIQD proteins integrate auxin and calcium signaling, two major signaling pathways, to control the cytoskeleton dynamics and cell shape of Arabidopsis.

plant biology↗

bioRxiv2017

Regulation of intercellular TARGET OF MONOPTEROS 7 protein transport in the Arabidopsis root

Intercellular communication coordinates hypophysis establishment in the Arabidopsis embryo. Previously, TARGET OF MONOPTEROS 7 (TMO7) was reported to be transported to the hypophysis, the founder cell of the root cap, and RNA suppression experiment implicated its function in embryonic root development. However, it remained unclear what protein properties and mechanisms mediate TMO7 protein transport, and what role the movement plays in development. Here, we report that in the post-embryonic root, TMO7 and its close relatives are transported into the root cap through plasmodesmata in a sequence, but not size dependent manner. We also show that nuclear residence is critical for TMO7 transport, and postulate that modification, potentially phosphorylation, labels TMO7 for transport. Additionally, three novel CRISPR/Cas9-induced tmo7 alleles confirmed a role in hypophysis division, but suggest complex redundancies with close relatives in root formation. Finally, we demonstrate that TMO7 transport is biologically meaningful, as local expression partially restores hypophysis division in a plasmodesmatal protein transport mutant. Our study identifies motifs and amino acids critical for TMO7 protein transport and establishes the importance of TMO7 in hypophysis and root development.\n\nSummary StatementUnique protein motifs, subcellular localization and post-translational modification, rather than protein size regulate plasmodesmatal transport of TMO7 family proteins during Arabidopsis root development.

plant biology↗