Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.06.03.597090

OsAAI1-OsMADS25 module orchestrates root morphogenesis by fine-tuning IAA in drought stressed rice

Xu, N.·Luo, R.·Long, Q.·Man, J.·Yin, J.·Liao, H.·Jiang, M.
View original source ↗Export metadata ↓

Abstract

Indole-3-acetic acid (IAA) plays a critical role as a plant hormone in regulating the growth and development of the root system in plants, particularly in enhancing their ability to withstand abiotic stress. In this study, we found that overexpression of OsAAI1 promoted the growth of rice root system. The length of primary root, the number of lateral roots, the density of lateral roots, and the number of adventitious roots of overexpression of OsAAI1 (OE19) were significantly better than those of the wild type (ZH11) and the mutant line (osaai1), and the IAA content of OE19 was significantly higher than those of ZH11 and osaai1. We also found that exogenous application of IAA could compensate for the root growth defect caused by the osaai1 mutation. OE19 had the highest number and widest distribution of total roots under the water-cut drought treatment, and exogenous application of IAA attenuated the growth inhibitory effect of drought stress on osaai1. Our study also revealed that OsAAI1 interacts with the MADS-box family transcription factor OsMASD25. Additionally, the application of IAA helped alleviate the growth inhibitory effects of drought stress on osmads25.Importantly, OsMADS25 interaction with OsAAI1 was found to enhance the transcriptional expression of its downstream target genes LAX1 and OsBAG4, which are crucial genes in rices response to drought stress. These findings suggest that OsAAI1 and OsMADS25 are crucial in rices drought acclimation process by regulating downstream gene expression and influencing the IAA signaling pathway. Author summaryThe root system is a crucial organ for crop plants as it facilitates the absorption of water and nutrients, contributing to their drought resistance. Indole-3-acetic acid (IAA) plays a pivotal role in the growth of various types of roots in plants. Under drought stress conditions, changes in IAA levels and transport can impact the morphology of plant roots. This research illustrates that OsAAI1 positively influences rice root development and enhances the plants response to drought stress through the auxin signaling pathway. The study reveals a physical interaction between OsAAI1 and the transcription factor OsMADS25. This interaction boosts the expression of the auxin synthesis gene OsYUC4 and suppresses the auxin inhibitory factor OsIAA14, thereby promoting the auxin signaling pathway, stimulating rice root growth, and enhancing the plants ability to withstand drought. Furthermore, the interaction between OsAAI1 and OsMADS25 has been found to also positively affect the expression of the genes LAX1 and OsBAG4, which is associated with activated drought resistance in rice plants.

Explore related subjects

plant biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Xu, N., Luo, R., Long, Q., Man, J., Yin, J., Liao, H., Jiang, M.. 2024-06-03. OsAAI1-OsMADS25 module orchestrates root morphogenesis by fine-tuning IAA in drought stressed rice. https://doi.org/10.1101/2024.06.03.597090

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

MpILR1 Hydrolyzes Jasmonate-Amino Acid Conjugates to Activate dn-iso-OPDA Signaling in Marchantia polymorpha.

Jasmonates are essential phytohormones that coordinate defense responses and developmental programs across land plants. In angiosperms, the active jasmonate ligand jasmonoyl-L-isoleucine (JA-Ile), is produced through GH3-mediated conjugation of jasmonic acid to isoleucine and JA-Ile homeostasis is further shaped by ILR1/ILL-family amidohydrolases. In contrast, the primary bioactive jasmonate ligand in bryophytes, dinor-12-oxo-phytodienoic acid (dn-iso-OPDA), is inactivated through conjugation with amino acids, raising the question of whether these conjugates constitute a reversible hormone reservoir or an irreversible catabolic end point. Although the ILR1-like family has been characterized extensively for its role in auxin and jasmonate homeostasis in angiosperms, its function in bryophytes remains basically unexplored. Here we show that MpILR1, the sole Marchantia ortholog of the ILR1/ILL family, hydrolyzes a specific subset of dn-iso-OPDA-amino acid conjugates in vivo. Loss-of-function Mpilr1 mutants exhibit enhanced accumulation of dn-iso-OPDA conjugated to hydrophobic amino acids (Val, Leu and Ile) but not to hydrophilic residues (His, Glu and Gln), demonstrating substrate-selective hydrolysis. MpILR1 hydrolytic activity is required for full dn-iso-OPDA-mediated responses, including transcriptional activation and defense against gastropod herbivory. These findings establish MpILR1 as a key positive regulator of jasmonate signaling in Marchantia polymorpha and suggest that hormone conjugation/deconjugation is an ancient regulatory mechanism evolved during plant terrestrialization.

plant biology↗
bioRxiv2026

Drought-Spec-Net: Early Tomato Drought Detection and Potential Yield-Impact Assessment Using Vis NIR Data

Drought stress significantly reduces tomato (Solanum lycopersicum L.) productivity, and early detection is critical to minimize yield losses through timely interventions. In this study, we developed Drought-Spec-Net, a hybrid 1D convolutional neural network that integrates local and global spectral feature extraction to detect early drought stress from visible and near infrared (Vis NIR) spectra data of tomato seedlings. The model was trained on 378 samples using an 80:20 train test split, with 20% of the training set reserved for validation. DroughtSpecNet outperformed the evaluated baseline and state of the art models, achieving 97% accuracy, 95% precision, 98% recall, and an F1 score of 97%. To improve the agronomic interpretation of the model outputs, predicted drought probabilities were converted into a literature-informed potential yield impact indicator using a maximum impact level of 60%. On the test set (76 samples), mapped potential yield-impact values ranged from 0% to 60%, with an average reduction of 12.97%. We also conducted an initial experiment using our greenhouse RGB dataset, collected daily from drought treated and well-watered tomato plants at West Virginia State University (WVSU). From this dataset, 44 images were selected for ilastik-based canopy segmentation, producing plant-level drought severity indices (DSI) with a mean of 0.28, median of 0.14, and range of 0.01 to 0.91. Additionally, we trained and fine-tuned a large language model (LLM) based on PLLaMA7BInstruct, called AgriLLaMA, for automated agronomic report generation from Drought-Spec-Net outputs. The generated reports summarize predicted stress levels, mapped potential yield impacts, and preliminary management considerations. This integrated approach not only improves early drought stress detection but also delivers quantitative and interpretable estimates of potential productivity losses, providing a complete framework connecting physiological stress detection to actionable agricultural outcomes.

plant biology↗
bioRxiv2026

BSA101: Unlocking Historical Mutant Collections with BSA-Seq

Forward genetics is a powerful approach for gene discovery, but identifying causal mutations becomes difficult when mutants are maintained in heterogeneous populations with uncertain pedigrees. This is exemplified by classical tasselseed (ts) mutants, which have long served as a genetic model for studying sex determination and carpel suppression. Decades of repeated outcrossing to diverse inbred lines have created substantial genetic heterogeneity, limiting the effectiveness of conventional bulked-segregant analysis sequencing (BSA-Seq). To address this, we developed a BSA-Seq framework that integrates flexible experimental designs, multiple reference genomes, and complementary statistical methods tailored for genetically heterogeneous populations. Applying this framework revealed that reference genome selection is critical for mapping success and that Euclidean distance raised to the fourth power (ED4) outperformed homozygosity mapping (HM). Furthermore, the framework enables simultaneous mapping of multiple mutations within a single population, eliminating the need for additional mapping populations. Applying this framework to 26 ts mutant stocks from the Maize Genetics Cooperation Stock Center, we successfully mapped 24 mutants to genomic intervals containing known ts genes, while the remaining mutants mapped to distinct genomic intervals, defining novel candidate regions underlying carpel suppression. Together, these results demonstrate that historical mutant collections represent an underutilized resource for gene discovery and establish a generalizable mapping strategy for unlocking their genetic potential across diverse species.

plant biology↗