Biology subjects

Berhin, A.

Publications and source records attributed to Berhin, A..

5 recordsLinked to original sources

bioRxiv2025

From Genes to Glands: Unraveling the Pivotal Influence of NtAGL66, an AGAMOUS-like Transcription Factor, on Glandular Trichome Development in Nicotiana tabacum

Glandular trichomes are specialized epidermal structures that play an essential role in plant defense by synthesizing, storing, and secreting specialized metabolites. This study investigates the function of NtAGL66, an AGAMOUS-like gene in Nicotiana tabacum, uncovering its role in the development of secretory heads in long glandular trichomes. Expression profiling reveals that NtAGL66 is specifically expressed in the developing secretory glands. Functional analyses show that NtAGL66 overexpression promotes the differentiation of the secretory structure, while CRISPR-Cas9-mediated knockout significantly reduces the capacity of trichomes to form functional secretory glands, highlighting its essential role in trichome specialization. Transcriptomic (RNA-seq) and functional genomic (DAP-seq) analyses indicate that NtAGL66 regulates also secondary metabolic pathways and is likely involved in broader transcriptional networks, including floral development. Notably, this includes genes such as NtTOE1, previously shown to control both floral organogenesis and glandular trichome formation in tomato. Moreover, NtAGL66 directly regulates the transcription factor NtGL2 through promoter binding. By identifying an AGAMOUS-like gene as a key regulator of secretory gland development, this study offers novel insights into the genetic mechanisms underlying glandular trichome differentiation and specialized metabolite biosynthesis in Solanaceae.

plant biology↗

bioRxiv2025

Insight into the genetic network governing long-stalked glandular trichome development in Nicotiana tabacum

Glandular trichomes play a pivotal role in plant defense against various biotic and abiotic stresses. To unravel the genetic network driving glandular trichome development in Nicotiana tabacum, we employed a transcriptional switch-based approach using heterologous expression of AmMIXTA, a MYB transcription factor from Antirrhinum majus. Through comprehensive RNA-seq analysis of transgenic tobacco seedlings where long-stalked glandular trichome development was induced in aerial parts, we identified a suite of differentially expressed genes, including several transcription factors, shedding light on the early transcriptional cascade governing this developmental process. Moreover, through confocal live cell imaging of transcriptional reporter lines, interaction studies and DAP-seq assays, we confirmed the involvement of NtZFP8, a gene identified in our study, in long-stalked glandular trichome development. Our findings support a model in which NtZFP8 regulates a gene network essential for this developmental process. This study underscores the effectiveness of our approach in decoding the regulatory landscape of glandular trichome development in N. tabacum and provides a valuable framework for future functional investigations. Key MessageGlandular trichomes are essential for plant defense. Using a transcriptional switch-based approach in Nicotiana tabacum, we identified key regulators, including NtZFP8, which controls long-stalked trichome development. Our study establishes a foundation for future functional analyses of candidate genes uncovered through this approach.

plant biology↗

bioRxiv2025

GPAT2 plays a role in the root cap cuticle formation of Arabidopsis that is not redundant to GPAT4 and GPAT8

During the first days after germination, the root cap protects the seeding with its cuticle, which persists until the embryonic outer root cap cell layer is shed. The polyester constituting the delicate Arabidopsis root cap cuticle of the primary root has an atypical composition, containing unsubstituted very-long-chain fatty acids in addition to the oxygenated fatty acids typically found in cutin. The sn2-glycerol-3-phosphate acyltransferases GPAT4 and GPAT8, which possess an active phosphatase domain, synthesize monoacylglycerols and are crucial for incorporating oxygenated fatty acids into the root cap cutin. Here, we show that the incorporation of very-long-chain fatty acids into cutin requires the glycerol-3-phosphate acyltransferase GPAT2, which lacks an active phosphatase domain and produces lysophosphatidic acids. The GPAT2 knockout alters the properties of the root cap leading to increased mucilage deposition but lower barrier properties. Furthermore, we demonstrate that the long-chain CoA synthetase LACS2 is required solely for the incorporation of oxygenated fatty acids into cutin, similar to GPAT4 and GPAT8. Consequently, two largely non-redundant pathways contribute to root cap cuticle formation in the primary root: both the LACS2/GPAT4/GPAT8- and the GPAT2-dependent pathways contribute non-redundantly to its barrier and surface properties. LACS2 also plays an important role in the formation of the root cap cuticle in emerging lateral roots, whereas GPAT2 has a minor function in this process. These findings underscore the diverse mechanisms by which cuticle synthesis is fine-tuned across plant organs and developmental stages to achieve specialized barrier and surface properties.

plant biology↗

bioRxiv2024

The GPAT4/6/8 clade functions in Arabidopsis root suberization non-redundantly with the GPAT5/7 clade required for suberin lamellae

SummaryLipid polymers such as cutin and suberin strengthen the diffusion barrier properties of the cell wall in specific cell types and are essential for water relations, mineral nutrition, and stress protection in plants. Land plant-specific glycerol-3-phosphate acyltransferases (GPATs) of different clades are central players in cutin and suberin monomer biosynthesis. Here, we show that the GPAT4/6/8 clade in Arabidopsis thaliana, which is known to mediate cutin formation, is also required for developmentally regulated root suberization, in addition to the established roles of GPAT5/7 in suberization. The GPAT5/7 clade is mainly required for abscisic acid-regulated suberization. In addition, the GPAT5/7 clade is crucial for the formation of the typical lamellated suberin ultrastructure observed by transmission electron microscopy, as distinct amorphous globular polyester structures were deposited in the apoplast of the gpat5 gpat7 double mutant, in contrast to the thinner but still lamellated suberin deposition in the gpat4 gpat6 gpat8 triple mutant. The intrinsic phosphatase activity of GPAT4, GPAT6, and GPAT8, which leads to monoacylglycerol biosynthesis, may be important for suberin biosynthesis. GPAT5/7 lack an active phosphatase domain. Notably, gpat5 gpat7 phenotypes were partially reverted by treatment with a phosphatase inhibitor or the expression of phosphatase-dead variants of GPAT4/6/8. Thus, GPATs that lack an active phosphatase domain, which are predicted to synthetize lysophosphatidic acids, might be crucial for the formation of the lamellated structure of suberin. GPATs with active and non-active phosphatase domains appear to have non-redundant functions and must cooperate to achieve the efficient biosynthesis of correctly structured suberin. Significance statementThe establishment of proper lamellated suberin in roots plays essential roles in regulating mineral nutrition and water relations in plants. The basis for the macromolecular arrangement determining the ultrastructure and properties of suberin lamellae is unknown. Here, we report that both the GPAT4/6/8 and GPAT5/7 clades of glycerol-3-phosphate acyltransferases (GPATs) contribute to suberin formation in Arabidopsis roots. In addition, we reveal that the GPAT5/7 clade is required for the formation of the lamellated suberin ultrastructure. Several lines of evidence suggest that the loss of phosphatase activity in GPATs might have played a crucial role in the formation of suberin lamellae during evolution.

plant biology↗

bioRxiv2021

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92 and MYB93), that are regulated by these two signals, and are sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing, lead to a dramatic reduction of suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips), through a compensatory mechanism. Through the functional analysis of these four MYBs we generated plants allowing unbiased investigations of endodermal suberin function without accounting for confounding effects due to Casparian strip defects, and could unravel specific roles of suberin in nutrient homeostasis.

plant biology↗