The Plant Journal最新文献

In the course of their life, plants continuously experience a wide range of unfavourable environmental conditions in the form of biotic and abiotic stress factors. The perception of stress via various organelles and rapid, tailored cellular responses are essential for the establishment of plant stress resilience. Mitochondria as the biosynthetic sites of energy equivalents in the form of ATP-provided in order to enable a multitude of biological processes in the cell-are often directly impacted by external stress factors. At the same time, mitochondrial function may fluctuate to a tolerable extent without the need to activate downstream retrograde signalling cascades for stress adaptation. In this Focus Review, we summarise the current state of knowledge on the perception and processing of stress signals by mitochondria and show which layers of retrograde signalling, that is, those involving transcription factors, metabolites, but also enzymes with moonlighting functions, enable communication with the nucleus. Also, light is shed on signal integration between mitochondria and chloroplasts as part of retrograde signalling. With this Focus Review, we aim to show ways in which organelle-specific communication can be further researched and the collected data used in the long-term to strengthen plant resilience in the context of climate change.

Calmodulin7 (CAM7) is a key transcription factor of Arabidopsis seedling development. CAM7 works together with HY5 bZIP protein to promote photomorphogenesis at various wavelengths of light. In this study, we show that AtMYB4, identified from a yeast two-hybrid screen, physically interacts with CAM7 and works as a positive regulator of photomorphogenesis at various wavelengths of light. CAM7 and HY5 directly bind to the promoter of AtMYB4 to promote its expression for photomorphogenic growth. On the other hand, ARA4, identified from the same yeast two-hybrid screen, works as a negative regulator of photomorphogenic growth specifically in white light. The double mutant analysis reveals that the altered hypocotyl elongation of atmyb4 and ara4 is either partly or completely suppressed by additional loss of function of CAM7. Furthermore, ARA4 genetically interacts with AtMYB4 in an antagonistic manner to suppress the elongated hypocotyl phenotype of atmyb4. The transactivation studies reveal that while CAM7 activates the promoter of AtMYB4 in association with HY5, ARA4 negatively regulates AtMYB4 expression. Taken together, these results demonstrate that working as a negative regulator of photomorphogenesis, ARA4 plays a balancing act on CAM7 and HY5-mediated regulation of AtMYB4.

ROS/redox signaling plays an important role in the regulation of signal transduction and acclimation pathways activated by multiple abiotic stresses and leaf senescence. However, the regulatory events that produce ROS under different stimuli are far from clear. Here, we report the elucidation of the molecular mechanism of an h type thioredoxin, AhTRX h2, positively regulates Al sensitivity and leaf senescence by promoting ROS. AhTRX h2 transcript levels increased greatly during both natural senescence and Al stress condition in peanut. Ectopic expression of AhTRX h2 in Arabidopsis conferred Al sensitivity as well as premature leaf senescence, manifested by multiple indices, including inhibiting root elongation, severe cell death, and accelerated expression of MC1 and CEX17. AhTRX h2 exhibited similar functions to AtTRX h2, as AhTRX h2 was able to restore the phenotypes of the AtTRX h2 defective mutant (trxh2-4) which showed Al tolerant and late senescence phenotypes. The knock down of AhTRX h2 markedly suppressed Al- and senescence-induced cell death in peanut. AhTRX h2 could recruit catalytic subunit of protein phosphatase 2A (PP2AC2) to form a stable complex. The interaction between AhTRX h2 and AtPP2AC2, as well as AhPP2AC2 and AtTRX h2 was also proved. Overexpression of AhPP2AC2 significantly enhanced Al sensitivity and leaf senescence in Arabidopsis. Protein stability assay revealed that AhTRX h2 was more stable during aging or aluminum stress. Moreover, PP2AC2 could greatly enhance the stability of AhTRX h2 in vivo. Consistent with these observations, overexpression of AhPP2AC2 effectively enhanced AhTRX h2-induced Al sensitivity and precocious leaf senescence. AhTRX h2 and AhPP2AC2 required ABA and ROS in response to cell death under Al stress and senescence, and it was evidence to suggest that ABA acted upstream of ROS in this process. Together, AhTRX h2 and AhPP2AC2 constitute a stable complex that promotes the accumulation of ABA and ROS, effectively regulate cell death. These findings suggest that TRX h2-PP2AC2-mediated pathway may be a widespread mechanism in regulating Al stress and leaf senescence.

Sorghum bicolor (sorghum) is a vital C4 monocotyledon crop cultivated in arid regions worldwide, valued for its significance in both human and animal nutrition. Despite its agricultural prominence, sorghum research has been hindered by low transformation frequency. In this study, we examined sorghum transformation using the pVS1-VIR2 ternary vector system for Agrobacterium, combined with the morphogenic genes BABY BOOM and WUSCHEL2 and selection using G418. We optimized Agrobacterium-mediated infection, targeting key parameters such as bacterial optical density, co-cultivation time, and temperature. Additionally, an excision-based transformation system enabled us to generate transgenic plants free of morphogenic regulators. The method yielded remarkable transformation frequencies, reaching up to 164.8% based on total isolated plantlets. The same combination of ternary vector, morphogenic genes and geneticin-based selection also resulted in a marked increase in transformation efficiency of the Zea mays (maize) inbred line B104. The potential for genomic editing using this approach positions it as a valuable tool for the development of sorghum and maize varieties that comply with evolving European regulations. Our work marks a significant stride in sorghum biotechnology and holds promise for addressing global food security challenges in a changing climate.

In plants, pre-mRNA alternative splicing has been demonstrated to be a crucial tier that regulates gene expression in response to salt stress. However, the underlying mechanisms remain elusive. Here, we studied the roles of DIGEORGE-SYNDROME CRITICAL REGION 14-like (AtDGCR14L) in regulating pre-mRNA splicing and salt stress tolerance. We discovered that Arabidopsis AtDGCR14L is required for maintaining plant salt stress tolerance and the constitutively spliced and active isoforms of important stress- and/or abscisic acid (ABA)-responsive genes. We also identified the interaction between AtDGCR14L and splicing factor U1-70k, which needs a highly conserved three amino acid (TWG) motif in DGCR14. Different from wild-type AtDGCR14L, the overexpression of the TWG-substituted AtDGCR14L mutant did not change salt stress tolerance or pre-mRNA splicing of stress/ABA-responsive genes. Additionally, SWITCH3A (SWI3A) is a core subunit of the SWI/SUCROSE NONFERMENTING (SWI/SNF) chromatin-remodeling complexes. We found that SWI3A, whose splicing depends on AtDGCR14L, actively enhances salt stress tolerance. These results revealed that AtDGCR14L may play an essential role in crosstalk between plant salt-stress response and pre-mRNA splicing mechanisms. We also unveiled the potential role of SWI3A in controlling salt stress tolerance. The TWG motif in the intrinsically disordered region of AtDGCR14L is highly conserved and crucial for DGCR14 functions.

Tomato (Solanum lycopersicum L.) is an important model plant species in photomorphogenesis research. Ultraviolet B (UV-B) induces the dissociation of homodimers of the photoreceptor UV RESISTANCE LOCUS8 (UVR8) into monomers, which translocate into the nucleus. Nuclear accumulation of UVR8 is a prerequisite for its signaling function. Previous studies have reported that SUPPRESSOR OF PHYTOCHROME A-105 (SPA) family members may regulate UV-B signaling in Arabidopsis (Arabidopsis thaliana); however, the underlying mechanism is unknown. Here, we show that the tomato genome encodes four SPA (SlSPA) orthologs. Genome-edited Slspa3 mutants exhibited enhanced photomorphogenic responses in white light, suggesting that SlSPA3 inhibits general photomorphogenesis. By contrast, UVR8-mediated gene expression in response to UV-B was compromised in Slspa3 mutants, suggesting that SlSPA3 promotes UV-B signaling. UV-B-induced nuclear accumulation of UVR8, which is essential for UV-B signaling, was reduced in the Slspa3 mutants. Moreover, UV-B-induced nuclear accumulation of UVR8 was also reduced in the Arabidopsis spa1 spa2 spa3 and spa1 spa2 spa4 triple mutants, indicating a conserved mechanism in these two species. Notably, spa1 spa2 spa4 exhibited normal UV-B-induced interaction between UVR8 and the plant morphogenesis repressor CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1). This suggests that the well-established mechanisms of UVR8 nuclear retention remained unaffected in spa1 spa2 spa4. Thus, our work uncovered a potentially unrecognized mechanism by which SPA proteins regulate UV-B signaling through the promotion of UVR8 nuclear abundance in land plants.

Cotton seed development and fiber elongation are the inseparable and overlapped development processes requiring the continuous supply of sucrose as the direct carbon source. However, little is known about the molecular mechanism of how sucrose is transported from the source tissues (leaves) into growing cotton seeds. Here, we identify the function of a sucrose transporter gene, Sugars Will Eventually be Exported Transporter 10, GhSWEET10 in cotton seed development. GhSWEET10 encodes a functional sucrose transporter, predominantly expressing in the funiculus, inner seedcoat, and endosperm during fiber elongation. GhSWEET10 RNAi plants (GhSWEET10i) accumulated less sucrose and glucose in growing seeds and that led to shorter fibers and smaller seeds, whereas GhSWEET10 overexpressed plants (GhSWEET10OE) had bigger seeds and longer fibers with more sugar accumulation during fiber elongation. GhSWEET10 gene is transcriptionally controlled by the transcription factor GhDOFD45. GhDOFD45 knockout plants (GhDOFD45-KO) possessed the phenotypes of smaller seeds and shorter fibers like those of GhSWEET10i plants. Furthermore, GhSWEET10 mainly exports the sucrose from the funiculus into developing seeds according to the mimic-analysis of sucrose transporting. Collectively, all these findings show that GhDOFD45 positively regulates GhSWEET10 expression to mainly transport sucrose from leaves into developing cotton seeds. Our findings also imply that the sucrose transport into enlarging seeds benefits fiber development, and thus GhSWEET10 can be selected as a target of breeding novel cotton varieties with larger and more vigorous seeds.

Arsenic (As) is extremely toxic to plants, posing a serious concern for food safety. Identification of genes responsive to As is significative for figuring out this issue. Here, we identified a bHLH transcription factor OsbHLH6 that was involved in mediating the processes of As tolerance, uptake, and root-to-shoot translocation in rice. The expression of OsbHLH6 gene was strongly induced after 3 and 48 h of arsenite [As(III)] treatment. The OsbHLH6-overexpressed transgenic rice (OE-OsbHLH6) was sensitive to, while the knockout mutant of OsbHLH6 gene (Osbhlh6) was tolerant to As(III) stress by affecting the contents of reactive oxygen species (ROS) and non-protein thiols (NPT), etc. Knockout of OsbHLH6 gene increased significantly the As concentration in roots, but decreased extensively As accumulation in shoots, compared to that in OE-OsbHLH6 and WT plants. The transcripts of phytochelatins (PCs) synthetase encoding genes OsPCS1 and OsPCS2, as well as As(III) transporter encoding genes OsLsi1 and OsABCC1 were greatly abundant in Osbhlh6 mutants than in OE-OsbHLH6 and WT plants under As(III) stress. In contrast, the expression of OsLsi2 gene was extensively suppressed by As(III) in Osbhlh6 mutants. OsbHLH6 acted as a transcriptional activator to bind directly to the promoter and regulate the expression of OsPrx2 gene that encodes a peroxidase precursor. Moreover, overexpression of OsbHLH6 gene resulted in significant change of expression of amounts of abiotic stress-related genes, which might partially contribute to the As sensitivity of OE-OsbHLH6 plants. These findings may broaden our understanding of the molecular mechanism of OsbHLH6-mediated As response in rice and provide novel useful genes for rice As stress-resistant breeding.

Arabidopsis plants were grown in white light (400-700 nm) or in white light supplemented with far-red (FR) light peaking at 730 nm. FR-enriched light induced the typical shade avoidance syndrome characterized by enhanced length of seedling hypocotyl and leaf petiole. FR supplementation also caused a noticeable decrease in the carotenoid and chlorophyll content that was attributable to a block of pigment accumulation during plant development. The carotenoid decrease resulted from a downregulation of their biosynthesis pathway rather than carotenoid degradation. The losses of photosynthetic pigments are part of structural and functional rearrangements of the photosynthetic apparatus. The plastoquinone pool was chronically more oxidized in plants acclimated to white + FR light compared to white light-grown plants. Growth in FR-enriched light was associated with a higher photochemical efficiency of PSII compared to growth in white light and with a substantial increase in root and shoot biomass production. Light distribution between the photosystems was modified in favor of PSII by an increase in the PSII/PSI ratio and an inhibition of state transitions. Neither LHCII abundance nor nonphotochemical energy dissipation in the PSII chlorophyll antennae were modified significantly by the addition of FR light. A PSI supercomplex, not previously observed in Arabidopsis, was specifically found in plants grown in FR-enriched light. This large PSI complex contains a supplementary Lhca1-4 dimer, leading to a total of 6 LHCI antennae instead of 4 in the canonical PSI. Through those photosystem rearrangements and the synergistic interaction with white light, FR light is photosynthetically active and can boost photosynthesis and plant growth.

A well-known defense-associated steroidal glycoalkaloid (SGA) metabolic shift eliminates the bitterness and toxicity of ripe tomato fruits. This study was conducted to clarify the effects of MADS-RIN (RIN) and its cofactors on SGA metabolism in tomato fruits. Using a CRISPR/Cas9-based gene-editing system, we mutated RIN and two cofactor genes (FUL1 and FUL2). The observed changes to fruit color and size in the mutants reflected the overlapping and distinct effects of RIN, FUL1, and FUL2 on fruit ripening. According to a UPLC-MS/MS analysis, the RIN and cofactor mutants had decreased levels of the relatively non-toxic metabolite esculeoside A, but they accumulated toxic SGA pathway intermediates, suggesting RIN and its cofactors are directly involved in esculeoside A biosynthesis. Transcriptome and qPCR analyses detected the downregulated expression of GAME5, which encodes a key enzyme mediating esculeoside A biosynthesis. ChIP-seq and ChIP-qPCR analyses confirmed GAME5 is targeted by RIN. RIN was observed to activate GAME5 transcription by binding to two non-canonical CArG-boxes in the GAME5 promoter. Additionally, RIN promotes SGA metabolism independently of ethylene. Collectively, these findings enhance our understanding of the molecular mechanism governing tomato fruit ripening and SGA biosynthesis. Furthermore, they may be useful for improving tomato fruit quality and safety.