Soil salinization severely constrains the growth and sustainable production of Chrysanthemum morifolium. However, the molecular mechanisms underlying salt tolerance in chrysanthemum remain largely uncharacterized. To identify suitable materials for dissecting the molecular mechanisms of salt tolerance, four chrysanthemum cultivars were evaluated under salt stress. Among them, ‘Hangbaiju’ was identified as the most salt-tolerant cultivar as reflected by enhanced osmotic adjustment capacity, reduced membrane damage, and improved maintenance of photosynthetic performance. Based on this screening, comparative transcriptome sequencing was performed to identify candidate genes associated with salt stress response, leading to the identification of CmNHX1–4. CmNHX1–4 were localized to the tonoplast and exhibited sustained transcriptional activation during prolonged salt stress. Notably, CmNHX1–4 displayed distinct temporal and spatial expression patterns across roots and leaves. Functional assays further demonstrated that heterologous expression of CmNHX1–4 in yeast and Arabidopsis significantly enhanced salt tolerance. Moreover, K-means clustering and WGCNA analysis combined with promoter analysis of CmNHXs indicated the potential regulation of CmNHXs by WRKY transcription factors via W-box elements. Further experiments demonstrated that CmWRKY54 directly bound to the promoter of CmNHX1 and activated its transcription. Collectively, our findings reveal a novel regulatory module whereby CmWRKY54 enhances salt tolerance through activating NHX1 expression, which is potentially implicated in mediating the vacuolar sequestration of cytosolic Na+. These results expand our mechanistic understanding of salt tolerance mechanisms in chrysanthemum and provide potential candidate genes for salt tolerance improvement in horticultural crops.

Light and temperature can regulate auxin production which has been recently shown to be key during graft healing, suggesting that abiotic factors may be vital variables for future graft studies. Grafting is an important horticultural tool used to combine advantageous plant traits. Despite its broad usage, the mechanisms that underlie graft healing remain poorly understood. Recent work has highlighted the influence of high temperature-mediated auxin flow on graft success. Light and temperature sensing utilize partially overlapping mechanisms to regulate auxin biosynthesis, signaling, and transport. In this review, we explore the sensors and transcriptional regulators that modulate auxin response, specifically emphasizing how these components regulate graft success and vascular reconnection. We also discuss areas of graft biology regulated by auxin and underexplored areas of photobiology that may be key to a better understanding of graft mechanisms. This review underscores the importance of translating genetic findings from model systems into horticultural crops to expand our knowledge of economically valuable techniques like grafting.

Arbuscular mycorrhizal symbiosis (AMS) is a ubiquitous mutualistic interaction between many terrestrial plants and fungi, with lipids playing a pivotal role in nutrient exchange. However, few genetic regulators of AMS have been functionally validated in tomato. To investigate candidate genes, we employed CRISPR‐Cas9 and VIGS to generate knockout and knockdown lines. A comprehensive suite of molecular biology techniques, including yeast‐1/2‐hybridization, BiFC, ChIP‐qPCR, and RNA‐sequencing, was used to elucidate the regulatory roles of SlWRI5a, SlHY5, and SlFatM in fatty acid (FA) biosynthesis and AMS in tomato. FA composition was analyzed using gas chromatography. In this study, we validated SlWRI5a and SlFatM as key regulators of 16‐carbon FA biosynthesis during AMS in tomato and demonstrated physical interactions between SlWRI5a and SlHY5. SlHY5 expression was induced by AMS and promoted root FA biosynthesis. Finally, we demonstrated that SlWRI5a and SlHY5 can co‐regulate SlFatM‐mediated FA accumulation, thereby influencing AMF colonization efficiency in tomato. Our findings reveal the SlWRI5a/SlHY5–SlFatM regulatory module, offering new insights into lipid‐mediated AMS in tomato. This work also highlights a novel role for HY5 during fungal symbiosis, underscoring its broader significance in plant–microbe interactions.

Extreme weather events, including high temperatures, frequently occur and adversely affect crop growth, posing substantial challenges to global agriculture. MicroRNAs (miRNAs) play integral roles in regulating plant growth and responses to various stresses. In this study, we reveal that microRNA164a (miR164a) in tomato (Solanum lycopersicum) is a pivotal element that exhibits a rapid positive response to heat stress (HS) among multiple miRNAs, while its target NO APICAL MERISTEM 3 (NAM3) shows an opposite complementary response. MiR164a/b-5p-deficient mutant and NAM3-overexpressing plants resulted in increased sensitivity to HS, whereas mutants with reduced NAM3 levels exhibited enhanced thermotolerance. Importantly, HS-induced reactive oxygen species (ROS) accumulation and antioxidant enzyme activities were positively regulated by miR164a and negatively by NAM3, respectively. Furthermore, we demonstrated that NAM3 transcriptionally activated the expression of HSFA4b, and silencing HSFA4b improved tomato thermotolerance. HSFA4b repressed the expression of the antioxidant gene APX1 and the heat shock protein (HSP) gene HSP90, disrupting redox homeostasis and exacerbating oxidative stress. Our findings unveil a pivotal regulatory pathway governed by the miR164a-NAM3 module that confers thermotolerance in tomato via its influence on ROS-related and HSP pathways. These findings provide valuable insights into the molecular mechanisms that underpin tomato thermotolerance, which are crucial for advancing sustainable agricultural practices, particularly in the face of the challenges presented by global climate change.

Cold stress is a major environmental challenge affecting the production of crops. Calcium‐dependent protein kinases (CDPKs/CPKs) are crucial regulators relaying calcium (Ca 2+ ) signals into cellular stress responses. However, the specific mechanisms of CPKs in regulating cold stress signaling are not well understood. In this study, through genetic, physiological and molecular biology assays, we characterized the function of CPK27 in enhancing tomato cold tolerance. We found that CPK27 stimulates flavonoid biosynthesis in a Ca 2+ ‐dependent manner, which in turn boosts the plant's tolerance. Tomato plants lacking CPK27 ( cpk27 ) showed decreased flavonoid levels under cold stress, accompanied by the increased sensitivity to cold. Activated by cold stress, CPK27 accumulates within the nucleus, where it physically interacts and phosphorylates ELONGATED HYPOCOTYL 5 (HY5) protein at serine23 (S23) and S57 residues, contributing to the cold‐induced accumulation of HY5 protein. HY5 directly binds to the promoter regions and stimulates the transcription of flavonoid biosynthesis genes. Further genetic analysis showed that CPK27 acts upstream of HY5, and the flavonoid biosynthesis pathway activated by CPK27 is HY5‐dependent. Our study elucidates the regulatory mechanism whereby the CPK27‐HY5 molecule integrates cold‐triggered Ca 2+ signals with flavonoid biosynthesis pathways to confer cold stress tolerance, thereby uncovering the key strategy for cold signal transduction.

Arbuscular mycorrhizal symbiosis (AMS) is a ubiquitous mutualistic interaction between many terrestrial plants and fungi, with lipids playing a pivotal role in nutrient exchange. However, few genetic regulators of AMS have been functionally validated in tomato. To investigate candidate genes, we employed CRISPR-Cas9 and VIGS to generate knockout and knockdown lines. A comprehensive suite of molecular biology techniques, including yeast-1/2-hybridization, BiFC, ChIP-qPCR, and RNA-sequencing, was used to elucidate the regulatory roles of SlWRI5a, SlHY5, and SlFatM in fatty acid (FA) biosynthesis and AMS in tomato. FA composition was analyzed using gas chromatography. In this study, we validated SlWRI5a and SlFatM as key regulators of 16-carbon FA biosynthesis during AMS in tomato and demonstrated physical interactions between SlWRI5a and SlHY5. SlHY5 expression was induced by AMS and promoted root FA biosynthesis. Finally, we demonstrated that SlWRI5a and SlHY5 can co-regulate SlFatM-mediated FA accumulation, thereby influencing AMF colonization efficiency in tomato. Our findings reveal the SlWRI5a/SlHY5-SlFatM regulatory module, offering new insights into lipid-mediated AMS in tomato. This work also highlights a novel role for HY5 during fungal symbiosis, underscoring its broader significance in plant-microbe interactions.

Cold stress is a major environmental challenge affecting the production of crops. Calcium-dependent protein kinases (CDPKs/CPKs) are crucial regulators relaying calcium (Ca2+) signals into cellular stress responses. However, the specific mechanisms of CPKs in regulating cold stress signaling are not well understood. In this study, through genetic, physiological and molecular biology assays, we characterized the function of CPK27 in enhancing tomato cold tolerance. We found that CPK27 stimulates flavonoid biosynthesis in a Ca2+-dependent manner, which in turn boosts the plant's tolerance. Tomato plants lacking CPK27 (cpk27) showed decreased flavonoid levels under cold stress, accompanied by the increased sensitivity to cold. Activated by cold stress, CPK27 accumulates within the nucleus, where it physically interacts and phosphorylates ELONGATED HYPOCOTYL 5 (HY5) protein at serine23 (S23) and S57 residues, contributing to the cold-induced accumulation of HY5 protein. HY5 directly binds to the promoter regions and stimulates the transcription of flavonoid biosynthesis genes. Further genetic analysis showed that CPK27 acts upstream of HY5, and the flavonoid biosynthesis pathway activated by CPK27 is HY5-dependent. Our study elucidates the regulatory mechanism whereby the CPK27-HY5 molecule integrates cold-triggered Ca2+ signals with flavonoid biosynthesis pathways to confer cold stress tolerance, thereby uncovering the key strategy for cold signal transduction.

Plant cytochrome P450 (CYP) superfamily, the largest enzyme metabolism family, has been identified in many species and plays a vital role in plant development and stress response via secondary metabolite biosynthesis. A comprehensive identification and functional investigation of CYPs in tomato plants would contribute to deeper understanding of their biological significance. In this study, 268 tomato CYP genes were identified and found to be unevenly located on 12 chromosomes. Based on the phylogenetic analysis, these 268 SlCYPs were classed into two distinct clades (A-type and non-A-type) and nine clans, including 48 families. Moreover, 67 tandem and 22 WGD (whole genome duplication)/segmental duplication events were detected, of which 12 SlCYP genes experienced both WGD/segmental and tandem duplication events, indicating that tandem duplication plays a major role in the expansion of the SlCYP family. Besides, 48 pairs containing 41 SlCYP and 44 AtCYP genes were orthologous, while 216 orthologous pairs were obtained between tomato and potato. The expression level of all SlCYP genes in tomato tissues at different development stages was analyzed, and most expressed SlCYPs showed a tissue-specific pattern. Meanwhile, 143 differentially expressed SlCYPs were identified under cold stress. Furthermore, the RT-qPCR results indicated that SlCYPs may be involved in fruit ripening and cold tolerance in tomato seedlings. These findings provide valuable insights into the evolutionary relationships and functional characteristics of SlCYPs, which can be utilized for further investigation of fruit metabolic pathways and cold tolerance in tomato.

Summary Plant secreted peptides RAPID ALKALINISATION FACTORs (RALFs), which act through the receptor FERONIA (FER), play important roles in plant growth. However, it remains unclear whether and how RALF‐FER contributes to the trade‐off of plant growth–defense. Here, we used a variety of techniques such as CRISPR/Cas9, protein–protein interaction and transcriptional regulation methods to investigate the role of RALF2 and its receptor FER in regulating lignin deposition, root growth, and defense against Fusarium oxysporum f. sp. lycopersici (Fol) in tomato (Solanum lycopersicum). The ralf2 and fer mutants show reduced primary root length, elevated lignin accumulation, and enhanced resistance against Fol than the wild‐type. FER interacts with and phosphorylates MYB63 to promote its degradation. MYB63 serves as an activator of lignin deposition by regulating the transcription of dirigent protein gene DIR19. Mutation of DIR19 suppresses lignin accumulation, and reverses the short root phenotype and Fol resistance in ralf2 or fer mutant. Collectively, our results demonstrate that the RALF2‐FER‐MYB63 module fine‐tunes root growth and resistance against Fol through regulating the deposition of lignin in tomato roots. The study sheds new light on how plants maintain the growth–defense balance via RALF‐FER.

Cold stress restricts the metabolic and physiological activities of plants, thereby affecting their growth and development. Although broad-complex, tramtrack, and bric-à-brac (BTB) proteins are essential for diverse biological processes and stress responses, the mechanisms underlying BTB-mediated cold responses remain not fully understood. Here, we characterize the function of the cold-induced SlBTB19 protein in tomato (Solanum lycopersicum). Overexpression of SlBTB19 resulted in increased plant sensitivity to cold stress, whereas SlBTB19 knockout mutants exhibited a cold-tolerance phenotype. Further analyses, including protein-protein interaction studies and cell-free degradation assays, revealed that SlBTB19 interacts with and destabilizes the transcription factor SlWRKY2. Using virus-induced gene silencing (VIGS) to silence SlWRKY2 in both wild-type and slbtb19 mutants, we provided genetic evidence that SlWRKY2 acts downstream of SlBTB19 in regulating cold tolerance. Importantly, we demonstrated that SlWRKY2 positively regulates cold tolerance in a CRT/DRE binding factor (CBF)-dependent manner. Under cold stress, SlWRKY2 binds to the W-box in the CBF1 and CBF3 promoters, directly activating their expression. In summary, our findings identify a SlBTB19-SlWRKY2 module that negatively regulates the CBF-dependent cold tolerance pathway in tomato.

B-box (BBX) proteins are an important class of zinc finger transcription factors that play a critical role in plant growth and stress response. However, the mechanisms of how BBX proteins participate in the cold response in tomato remain unclear. Here, using approaches of reverse genetics, biochemical and molecular biology we characterized a BBX transcription factor, SlBBX17, which positively regulates cold tolerance in tomato (Solanum lycopersicum). Overexpressing SlBBX17 enhanced C-repeat binding factor (CBF)-dependent cold tolerance in tomato plants, whereas silencing SlBBX17 increased plant susceptibility to cold stress. Crucially, the positive role of SlBBX17 in CBF-dependent cold tolerance was dependent on ELONGATED HYPOCOTYL5 (HY5). SlBBX17 physically interacted with SlHY5 to directly promote the protein stability of SlHY5 and subsequently increased the transcriptional activity of SlHY5 on SlCBF genes under cold stress. Further experiments showed that cold-activated mitogen-activated protein kinases, SlMPK1 and SlMPK2, also physically interact with and phosphorylate SlBBX17 to enhance the interaction between SlBBX17 and SlHY5, leading to enhanced CBF-dependent cold tolerance. Collectively, the study unveiled a mechanistic framework by which SlMPK1/2-SlBBX17-SlHY5 regulated transcription of SlCBFs to enhance cold tolerance, thereby shedding light on the molecular mechanisms of how plants respond to cold stress via multiple transcription factors.

Chilling temperatures induce an increase in cytoplasmic calcium (Ca2+) ions to transmit cold signals, but the precise role of Calmodulins (CaMs), a type of Ca2+ sensor, in plant tolerance to cold stress remains elusive. In this study, we characterized a tomato (Solanum lycopersicum) CaM gene, CALMODULIN6 (CaM6), which responds to cold stimulus. Overexpressing CaM6 increased tomato sensitivity to cold stress whereas silencing CaM6 resulted in a cold-insensitive phenotype. We showed that CaM6 interacts with Inducer of CBF expression 1 (ICE1) in a Ca2+-independent process and ICE1 contributes to cold tolerance in tomato plants. By integrating RNA-sequencing (RNA-seq) and chromatin immunoprecipitation-sequencing (ChIP-seq) assays, we revealed that ICE1 directly altered the expression of 76 downstream cold-responsive (COR) genes that potentially confer cold tolerance to tomato plants. Moreover, the physical interaction of CaM6 with ICE1 attenuated ICE1 transcriptional activity during cold stress. These findings reveal that CaM6 attenuates the cold tolerance of tomato plants by suppressing ICE1-dependent COR gene expression. We propose a CaM6/ICE1 module in which ICE1 is epistatic to CaM6 under cold stress. Our study sheds light on the mechanism of plant response to cold stress and reveals CaM6 is involved in the regulation of ICE1.

\u3010Objective\u3011<\/strong>This study analyzed the effects of supplementary far-red light (FR) on the growth and abiotic stress tolerance of pepper seedlings, aiming to provide a theoretical basis on precise light environments for cultivating high quality vegetable seedlings.<\/p><\/sec>\u3010Method\u3011<\/strong>In this study, Bola Hongshuai pepper cult

Cold is a common abiotic stress that seriously affects plant growth and development. MYB transcription factors are regulatory molecules that play important roles in various biological processes. We have previously demonstrated that SlMYB15 positively regulates cold tolerance in tomato. However, the underlying mechanism of SlMYB15-induced cold tolerance remains largely unexplored. Here, cold-induced SlMYB15 was found to be targeted by Solanum lycopersicum (sly)-miR156e-3p, which was decreased by cold stimulus in tomato. Tomato plants overexpressing sly-MIR156e-3p displayed significant enhancement in susceptibility to cold stress, while silencing of sly-miR156e-3p by an artificial microRNA interference strategy caused tomato plants to be more tolerant to cold. Moreover, both overexpression of SlMYB15 and silencing of sly-miR156e-3p increased the accumulation of ABA. SlMYB15 directly binds to the promoter regions of ABA biosynthesis and signalling genes, SlNCED1 and SlABF4, resulting in enhanced cold tolerance. Further experiments showed that SlMYB15 and sly-miR156e-3p also coordinated the cold tolerance of tomato via the reactive oxygen species (ROS) signalling pathway, as reflected by the increased expression of SlRBOH1, enhanced H2O2 and O2•-accumulation, and amplified activity of antioxidant enzymes in SlMYB15-overexpressing and sly-miR156e-3p-silenced plants. Taken together, our results demonstrate that SlMYB15 targeted by sly-miR156e-3p confers higher survivability to cold stress via ABA and ROS signals. This study provides valuable information for breeding improved crop cultivars better equipped with cold tolerance.

[目的]研究补照适量远红光(FR)对辣椒幼苗生长发育和非生物胁迫抗性的调控作用,旨在为实际生产过程中利用精确的光环境调控手段培育壮苗提供理论依据.[方法]以辣椒'博辣红帅'品种为研究材料,将苗龄7 d的辣椒幼苗置于LED光源对照光谱(NL;红R/蓝B=3/1,光量子通量密度PPFD为150 μmol·m-2·s-1)及在此基础上分别补充10 μmol.m-2·s-1远红光(6％FR)、20 μmol·m-2·s-1远红光(13％FR)和30 μmol·m-2·s-1远红光(20％FR)的处理组光谱环境条件下培养,并于苗龄21 d时进行低温和干旱处理.通过测定生物量、抗性相关基因表达、抗氧化酶活性、激素含量、叶绿素荧光参数以及叶片相对电导率等,探究补充6％FR对辣椒幼苗生长和非生物胁迫抗性的影响.[结果]与对照光谱相比,补充6％FR显著提高了辣椒幼苗株高、茎粗、干鲜重以及壮苗指数(P＜0.05).低温胁迫下,相比于对照光谱组,补充6％FR显著提高了辣椒叶片冷响应基因CBF1和抗氧化酶相关基因Cu/Zn-SOD、GR、APX、CAT,DHAR的表达水平,超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)活性比对照分别增加25.2％、53.6％、55.8％、72.7％和33.4％,抗逆相关激素脱落酸(ABA)的含量提高69.5％.同时,低温胁迫下补充6％FR后辣椒叶片PSII最大光化学效率(Fv/Fm)较对照光谱组显著升高,而相对电导率(REL)显著降低,表明补充6％FR缓解了低温下PSII光抑制和叶片细胞的损伤,提高了辣椒幼苗的耐冷性.此外,干旱胁迫下,相比于对照光谱组,补充6％FR使辣椒幼苗的抗氧化酶SOD、GR、APX、CAT、DHAR活性分别增加13.7％、38.0％.37.2％、27.6％和23.7％,ABA含量和PSII实际光化学效率(ΦPSⅡ)也显著升高,而REL则明显降低,表明补充6％FR减轻了干旱胁迫引起的PSII光抑制和膜脂过氧化,提高了辣椒幼苗的耐旱性.[结论]补充6％FR不仅可促使辣椒壮苗的形成,还可通过增加抗氧化酶活性和ABA含量提高辣椒幼苗对低温胁迫和干旱胁迫的抗性.

Photosynthetic pigments in higher plants, including chlorophyll and carotenoid, are crucial for photosynthesis and photoprotection. Previous studies have shown that nitric oxide (NO) plays a dual role in plant photosynthesis. However, how pigment biosynthesis is suppressed by NO remains unclear. In this study, we generated NO-accumulated gsnor mutants, applied exogenous NO donors, and used a series of methods, including reverse transcription quantitative PCR, immunoblotting, chromatin immunoprecipitation, electrophoretic mobility shift, dual-luciferase, and NO content assays, to explore the regulation of photosynthetic pigment biosynthesis by NO in tomato. We established that both endogenous and exogenous NO inhibited pigment accumulation and photosynthetic capacities. High levels of NO stimulated the degradation of LONG HYPOCOTYL 5 (HY5) protein and further inactivated the transcription of genes encoding protochlorophyllide oxidoreductase C (PORC) and phytoene synthase 2 (PSY2)—two enzymes that catalyze the rate-limiting steps in chlorophyll and carotenoid biosynthesis. Our findings provide a new insight into the mechanism of NO signaling in modulating HY5-mediated photosynthetic pigment biosynthesis at the transcriptional level in tomato plants.

设施栽培冬春生产中的低温逆境严重影响番茄等喜温作物的光合作用,而不适宜的光强、光周期、光质等光环境加剧了作物的低温光抑制,导致产量降低和品质变劣.因此,解析植物响应光温逆境的生理分子机制对冬春季节生产中作物抗逆性调控不可或缺.近年来,植物响应光温逆境的分子机制逐渐清晰,然而光温信号整合因子及其功能还有待进一步挖掘.基于此,对番茄响应光温逆境的生理分子机制进行了综述,重点讨论了光及其信号对植物低温抗性的影响,并分析了此领域研究中存在的问题及今后研究的方向,以期为减轻番茄的逆境危害、提高产量和品质等提供参考,也为深入探索新的光温互作因子及其功能奠定基础.

The induction of C-repeat binding factors (CBFs) is crucial for plant survival at low temperatures. Therefore, understanding the mechanisms that regulate CBF transcription is vital for the future development of crops with increased cold tolerance. Here, we provide evidence for the existence of a LONG HYPOCOTYL 5 (HY5)-MYB15-CBFs transcriptional cascade that plays a crucial role in the cold response in tomato. The exposure of tomato plants to cold (4°C) increased the levels of HY5, MYB15 and CBFs transcripts. Moreover, mutations in HY5 or MYB15 decreased the levels of CBF transcripts. In contrast, overexpression of HY5 or MYB15 increased CBF transcript abundance. Crucially, the HY5 transcription factor activated the expression of MYB15 by directly binding to the promoter region, while both HY5 and MYB15 activated the expression of CBF1, CBF2 and CBF3. Taken together, these data show that HY5 can directly regulate CBF transcript levels, and also influence CBF expression indirectly via MYB15. The coordinated action of HY5 and MYB15 allows precise regulation of CBF expression and subsequent cold tolerance. These findings provide an improved understanding of the molecular mechanisms affording transcriptional regulation of CBFs, which can be exploited in the future to enhance cold tolerance in crops.

Optimizing the photoprotection of different leaves as a whole is important for plants to adapt to fluctuations in ambient light conditions. However, the molecular basis of this leaf-to-leaf communication is poorly understood. Here, we used a range of techniques, including grafting, chlorophyll fluorescence, revers transcription quantitative PCR, immunoblotting, chromatin immunoprecipitation, and electrophoretic mobility shift assays, to explore the complexities of leaf-to-leaf light signal transmission and activation of the photoprotective response to light fluctuation in tomato (Solanum lycopersicum). We established that light perception in the top leaves attenuated the photoinhibition of both PSII and PSI by triggering photoprotection pathways in the bottom leaves. Local light promoted the accumulation and movement of LONG HYPOCOTYL5 from the sunlit local leaves to the systemic leaves, priming the photoprotective response of the latter to light fluctuation. By directly activating the transcription of PROTON GRADIENT REGULATION5 and VIOLAXANTHIN DE-EPOXIDASE, LONG HYPOCOTYL5 induced cyclic electron flow, the xanthophyll cycle, and energy-dependent quenching. Our findings reveal a systemic signaling pathway and provide insight into an elaborate regulatory network, demonstrating a pre-emptive advantage in terms of the activation of photoprotection and, hence, the ability to survive in a fluctuating light environment.