Biology subjects

Abreu, I. A.

Publications and source records attributed to Abreu, I. A..

3 recordsLinked to original sources

bioRxiv2024

OsbHLH089 and OsbHLH094 Modulate OsSLR1 Levels to Maintain Male Reproductive Fitness in Rice

DELLA proteins are a unique class of transcriptional regulators in plants, playing critical roles in diverse biological processes. Far from being only negative regulators of the Gibberellin (GA) signalling pathway, DELLAs act as central signalling hubs due to their versatile binding capacity and responsiveness to GA fluctuations. This adaptability allows DELLAs to interact with a wide array of proteins but also makes their functional study challenging: disruptions in DELLA function lead to pleiotropic effects across multiple pathways. To address this complexity, understanding DELLA interactors provides valuable insights into DELLAs nuanced functions and regulation. Building on this approach, we investigated novel OsSLR1 interactors, OsbHLH089 and OsbHLH094, members of the basic-helix-loop-helix transcription factor family. Our findings reveal that OsbHLH089 and OsbHLH094 are expressed in mature pollen grains, with the Osbhlh089/94 double mutant displaying smaller, indehiscent anthers and non-viable pollen, indicating their redundant role in pollen development during its late stages. Through ChIP-Seq and RNA-Seq analyses, we identified five target genes repressed by OsbHLH089 and OsbHLH094 (OsTDL1A, OsSPS1, OsDGD2{beta}, OspPGM, and OsDPE2) that are essential for pollen and anther development. Interestingly, we also observed the binding of these TFs to the OsSLR1 promoter. Notably, while other target genes were repressed, OsSLR1 was induced, with a significant protein accumulation in the double mutant compared to the Kitaake background in the late stages of pollen development. This suggests that OsSLR1 accumulation may compromise pollen viability, further highlighting the critical regulatory role of OsbHLH089 and OsbHLH094 in repressing OsSLR1 levels for proper pollen and anther development.

plant biology↗

bioRxiv2020

SUMOylation of rice DELLA SLR1 modulates transcriptional responses and improves yield under salt stress

DELLA proteins modulate GA signalling and are major regulators of plant plasticity to endure stress. DELLAs are mostly regulated at the post-translational level, and their activity relies on the interaction with upstream regulators and transcription factors (TFs). SUMOylation is a post-translational modification (PTM) capable of changing protein interaction and found to influence DELLA activity in Arabidopsis. We determined that SUMOylation of the single rice DELLA SLENDER RICE1 (SLR1) occurs in a lysine residue different from the one previously identified in Arabidopsis REPRESSOR OF GA (RGA). Remarkably, artificially increasing SUMOylated SLR1 (SUMO1SLR1) levels attenuated the penalty of salt stress on plant yield. Gene expression analysis revealed that the overexpression of SUMOylated SLR1 regulates key dioxygenases that modulate active GA levels, namely GA20ox2 and GA2ox3, which could partially explain the sustained productivity upon salt stress imposition. Besides, SLR1 SUMOylation blocked the interaction with the growth regulator YAB4, which may fine-tune GA20ox2 expression. Mechanistically, we propose that SLR1 SUMOylation disrupts the interaction with members of several transcription factor families to modulate gene expression. We found that SLR1 SUMOylation represents a novel mechanism modulating DELLA activity, which attenuates the impact of stress on plant performance. One sentence summaryRice plants show increased yield under salt stress when its gibberellin transcriptional regulator DELLA protein is artificially SUMOylated.

plant biology↗

bioRxiv2018

Synergistic binding of bHLH transcription factors to the promoter of the maize NADP-ME gene used in C4 photosynthesis is based on an ancient code found in the ancestral C3 state

C4 photosynthesis has evolved repeatedly from the ancestral C3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the worlds most productive crops. The C4 cycle is accomplished through cell-type specific accumulation of enzymes but cis-elements and transcription factors controlling C4 photosynthesis remain largely unknown. Using the NADP-Malic Enzyme (NADP-ME) gene as a model we aimed to better understand molecular mechanisms associated with the evolution of C4 photosynthesis. Two basic Helix-Loop-Helix (bHLH) transcription factors, ZmbHLH128 and ZmbHLH129, were shown to bind the C4 NADP-ME promoter from maize. These proteins form heterodimers and ZmbHLH129 impairs trans-activation by ZmbHLH128. Electrophoretic mobility shift assays indicate that a pair of cis-elements separated by a seven base pair spacer synergistically bind either ZmbHLH128 or ZmbHLH129. This pair of cis-elements is found in both C3 and C4 species of the PACMAD clade. Our analysis is consistent with this cis-element pair originating from a single motif present in the ancestral C3 state. We conclude that C4 photosynthesis has co-opted an ancient C3 regulatory code built on G-box recognition by bHLH to regulate the NADP-ME gene. More broadly, our findings also contribute to the understanding of gene regulatory networks controlling C4 photosynthesis.

plant biology↗