Biology subjects

Zhao, P.-X.

Publications and source records attributed to Zhao, P.-X..

9 recordsLinked to original sources

bioRxiv2023

Loss of OsARF18 confers glufosinate ammonium herbicide resistance in rice

Weed is one of the major biotic stresses that causes severe loss of crop yield. Herbicide is one of the most cost-effective ways to control weeds. Thus, the development of herbicide-resistant crops is critical for the application of herbicides. To isolate new glufosinate ammonium resistance loci, we screened a rice ethyl methyl sulfonate-mutagenized library and obtained the glufosinate ammonium-resistant mutant gar1-1. GAR1 encodes auxin response factor 18 (OsARF18). A G-to-A substitution in the coding region of OsARF18 results in loss of function of OsARF18 and thereby enhances glufosinate ammonium resistance of gar1-1, which was confirmed by three additional CRISPR/Cas9-edited gar1 alleles. GLUTAMINE SYNTHETASE 1;1 (OsGS1;1) and GLUTAMINE SYNTHETASE 1;2 (OsGS1;2) were upregulated in gar1-1 upon glufosinate ammonium treatment, directly contributing to increased GS activity that enhances glufosinate ammonium herbicide resistance. We further show that OsARF18 suppresses OsGS1;1 and OsGS1;2 expression. Comparative transcriptomic analyses reveal a huge shift in the gene expression profile involved in stress tolerance and growth. A large number of detoxification-related genes are enriched in gar1-1, which may also contribute to enhanced herbicide resistance. Moreover, stress tolerance-related genes are upregulated and growth-related genes are downregulated in gar1-1, consistent with the improved tolerance to salt and osmotic stress of gar1 mutants. Taken together, our study demonstrates that OsARF18 is a negative regulator of glufosinate ammonium resistance as well as salt and osmotic stress tolerance, suggesting a role in balancing the stress response and growth.

plant biology↗

bioRxiv2023

Root-derived long-range signals activate ABA synthesis in frd3 leaves to enhance drought resistance

Vascular plants have evolved sophisticated mechanisms of long-distance signaling to cope with environmental stress. Reactive oxygen species (ROS) act as systemic signals in plant stress responses. However, it is not known whether ROS serve as root-to-shoot signals in the drought response. Here, we show that ferric reductase defective3 (frd3) mutants exhibit enhanced drought resistance concomitant with increased NCED3 transcript levels and ABA contents in leaves. The frd3 mutants also have an elevated hydrogen peroxide (H2O2) level in roots and leaves compared with the wild type. Grafting experiments demonstrate that drought resistance can be conferred by the frd3 rootstock, suggesting that long-distance signals derived in frd3 roots trigger ABA level increases in leaves and thereby enhance drought resistance and that H2O2 is a strong candidate for long-distance signals. Furthermore, comparative transcriptome and proteomics analyses revealed that many genes and proteins involved in the abiotic stress response, ROS homeostasis, and signaling pathways were affected in the frd3 mutant, supporting the drought resistance phenotype. Taken together, our findings suggest that frd3 root-derived long-range signals activate ABA synthesis in leaves and enhance drought resistance, indicating possible root-to-shoot H2O2 signaling in the plant drought response.

plant biology↗

bioRxiv2023

The ABI3-ERF1 module mediates ABA-auxin crosstalk to regulate lateral root emergence

Lateral root (LR) development is regulated by hormones and environmental signals. Abscisic acid (ABA) is involved in LR development, but it is not well understood how ABA signaling interacts with auxin to regulate LR formation. Here, we report that Arabidopsis ERF1 is responsive to ABA during LR development and mediates the crosstalk between ABA and auxin signaling to regulate LR emergence. ABA attenuates ERF1-mediated excessive auxin accumulation with altered distribution known to inhibit LR emergence. ABI3 acts as a negative factor in LR emergence and transcriptionally activates ERF1 by binding to the RY motif in its promoter, and reciprocally, ERF1 activates ABI3, which forms a positive regulatory loop that enables rapid signal amplification. Notably, ABI3 physically interacts with ERF1, consequently reducing the cis element-binding activities of both ERF1 and ABI3 and thus attenuating ERF1-regulated transcription of PIN1, AUX1, and ARF7 involved in the modulation of LR emergence and ABI3-regulated ABI5 in ABA signaling, which may provide a molecular rheostat to avoid overamplification of auxin and ABA signaling. Taken together, our findings unveil the pivotal ABI3-ERF1 module that mediates the crosstalk between ABA and auxin signaling in LR emergence.

plant biology↗

bioRxiv2023

ERF1 inhibits lateral root emergence by promoting local auxin accumulation with altered distribution and repressing ARF7 expression

Lateral roots (LRs) are crucial for plants to sense environmental signals in addition to water and nutrient absorption. Auxin is key for LR formation, but the underlying mechanisms are not fully understood. Here we report that Arabidopsis ERF1 inhibits LR emergence by promoting local auxin accumulation with altered distribution and regulating auxin signaling. Loss of ERF1 increases LR density compared with the wild type, whereas ERF1 overexpression causes the opposite phenotype. ERF1 enhances auxin transport by upregulating PIN1 and AUX1, resulting in excessive auxin accumulation in the endodermal, cortical, and epidermal cells surrounding LR primordia. Furthermore, ERF1 represses ARF7 transcription, consequently affecting the expression of cell wall remodeling genes that facilitate LR emergence. Together, our study reveals that ERF1 integrates environmental signals to promote local auxin accumulation with altered distribution and repress ARF7, consequently inhibiting LR emergence in adaptation to fluctuating environments. HighlightsO_LIERF1 functions as a negative regulator of lateral root emergence C_LIO_LIERF1 enhances rootward and shootward auxin transport by directly upregulating the expression of PIN1 and AUX1, resulting in high local auxin accumulation and abnormal auxin distribution in the endodermal, cortical, and epidermal cells overlying lateral root primordia C_LIO_LIERF1 represses the transcription of ARF7 and cell wall remodeling genes in lateral root emergence C_LI

plant biology↗

bioRxiv2022

Nitrate-dependent salt tolerance mediated by OsNLP4-OsMADS27 module

Salt stress is a major constraint of plant growth and yield. Nitrogen (N) fertilizers are known to alleviate salt stress. However, the underlying molecular mechanisms remain unclear. Here we show that OsNLP4-OsMADS27 module controls nitrate-dependent salt tolerance in rice. The expression of OsMADS27 is specifically induced by nitrate. The OsMADS27 knockout mutants are more sensitive to salt stress than the wild type, whereas the OsMADS27 overexpression lines are more tolerant. Transcriptomic analyses revealed that OsMADS27 controls the expression of a number of known stress-responsive genes as well as those involved in ion homeostasis and antioxidation. We demonstrated that OsMADS27 directly binds to the promoter of OsHKT1.1 and OsSPL7 to regulate their expression. Notably, OsMADS27-mediated salt tolerance is nitrate-dependent and positively correlated with nitrate concentration. We further showed that OsNLP4, a nitrate-responsive key regulator in N metabolism and N use efficiency, positively regulates the expression of OsMADS27 by directly binding to the nitrate-responsive cis-element in its promoter, thereby transmitting the nitrate signal to OsMADS27 and conferring its nitrate dependence. Our results reveal the role of nitrate-responsive OsNLP4-OsMADS27 module and its downstream target genes in salt tolerance, filling the gap in the molecular mechanism of nitrate-dependent salt tolerance of rice. Moreover, OsMADS27 overexpression increased grain yield under salt stress in presence of sufficient nitrate, indicating that OsMADS27 is a promising candidate for the improvement of salt tolerance in rice.

plant biology↗

bioRxiv2021

AGL16 negatively modulates stress response to balance with growth

Sensile plants constantly experience environmental stresses in nature. They must have evolved effective mechanisms to balance growth with stress response. Here we report the MADS-box transcription factor AGL16 acting as a negative regulator in stress response. Loss-of-AGL16 confers resistance to salt stress in seed germination, root elongation, and soil-grown plants, while elevated AGL16 expression confers the opposite phenotypes compared with wild type. However, the sensitivity to ABA in seed germination is inversely correlated with AGL16 expression level. Transcriptomic comparison revealed that the improved salt resistance of agl16 mutant was largely attributed to enhanced expression of stress responsive transcriptional factors and genes involved in ABA signaling and ion homeostasis. We further demonstrated that AGL16 directly binds to the CArG motifs in the promoter of HKT1;1, HsfA6a, and MYB102 and represses their expression. Genetic analyses with double mutants also support that HsfA6a and MYB102 are target genes of AGL16. Taken together, our results show that AGL16 acts as negative regulator transcriptionally suppressing key components in stress response and may play a critical role in balancing stress response with growth.

plant biology↗

bioRxiv2019

Arabidopsis ERF109 regulates auxin transport-related genes in root development

The transcription factor ERF109 acts as a crosstalk node between jasmonic acid signaling and auxin biosynthesis by directly regulating YUC2 and ASA1 during lateral root formation in Arabidopsis. However, whether ERF109 regulates the auxin transport remains unclear. Here we report a mechanism of ERF109-mediated auxin transport in root system. Through root transcriptome comparison between erf109, wild type, and 35S:ERF109, we found that the genes PIN2 and PIN4, encoding the major membrane-based efflux carriers of auxin, were enriched in the overexpression line. In the promoters of these auxin transport genes, GCC-box cis elements were found and potentially bound by ERF109. Moreover, PID, encoding a key regulator in polar auxin transport, was found upregulated in 35S:ERF109 and down regulated in erf109. Yeast-one-hybrid and chromatin immunoprecipitation assays showed that ERF109 directly bound to the GCC-box of PIN2, PIN4, and PID. Genetic analyses with double mutants confirmed the function of ERF109 in the regulation of auxin transport in Arabidopsis roots. Taken together, our results show that ERF109 modulates auxin transport by directly regulating PIN2, PIN4 and PID. This ERF109-mediated auxin transport likely works together with ERF109-mediated auxin synthesis to establish auxin maxima for lateral root initiation.

plant biology↗

bioRxiv2019

MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement

Drought is one of the most severe environmental factors limiting plant growth and productivity. Plants respond to drought by closing stomata to reduce water loss. The molecular mechanisms underlying plant drought resistance are very complex and yet to be fully understood. While much research attention has been focused on the positive regulation of stomatal closure, less is known about its negative regulation, equally important in this reversible process. Here we show that the MADS-box transcriptional factor AGL16 acts as a negative regulator in drought resistance by regulating both stomatal density and movement. Loss-of-function mutant agl16 was more resistant to drought stress with higher relative water content, which was attributed to a reduced leaf stomatal density and more sensitive stomatal closure due to a higher leaf ABA level compared with wild type, while AGL16 overexpression lines displayed the opposite phenotypes. AGL16 is preferentially expressed in guard cells and down regulated in response to drought stress. The expression of CYP707A3 and AAO3 in ABA metabolism and SDD1 in stomatal development was altered by AGL16 as shown in agl16 and overexpression lines. Chromatin immunoprecipitation, transient transactivation, and yeast-one-hybrid assays demonstrated that AGL16 bound the CArG motif in the promoter of the CYP707A3, AAO3, and SDD1 to regulate their transcription, and therefore alter leaf stomatal density and ABA level. Taken together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

plant biology↗

bioRxiv2016

Arabidopsis MADS-box transcription factor AGL21 acts as environmental surveillance for seed germination by regulating ABI5

Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Abscisic acid (ABA) and its signaling play a vital role in integrating environmental information to regulate seed germination. MCM1/AGAMOUS/DEFICIENS/SRF (MADS)-box transcription factors are mainly known as key regulators of seed and flower development in Arabidopsis. However, their functions in seed germination are still poorly understood. Here we report that MADS-box transcription factor AGL21 negatively modulates seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 (ABI5) in Arabidopsis. AGL21 responds to multiple environmental stresses and plant hormones. The AGL21-overexpressing plants are hypersensitive to ABA, salt and osmotic stresses during seed germination and early post-germination growth, whereas agl21 mutants are less sensitive. AGL21 positively regulates ABI5 expression in seeds. Genetic analyses reveal that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrate that AGL21 could directly bind to the ABI5 promoter in plant cells. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.

plant biology↗