Gibberellin Biosynthesis Research Articles

Gibberellin biosynthesis, its roles in plant physiology and abiotic stress responses

Gibberellins (GAs) are a group of phytohormones that significantly impact plant growth and development processes, including seed germination, stem elongation, and fruit development. These diterpenoid acids are influenced by environmental factors such as light and temperature, which can alter their concentration and activity. Initially discovered in the 1920s in the fungus Gibberella fujikuroi, over 136 GAs have been identified in various plants, fungi, and bacteria. A particularly active form of gibberellin, GA3, is widely used in agriculture to promote cell elongation, induce the grow of seedless fruits and improve crop yields. The synthesis and regulation of gibberellins in plants involve complex biosynthetic pathways that integrate both endogenous and environmental signals. Additionally, GAs play a role in stress response, helping plants adapt to challenging conditions like salinity and water scarcity. Research continues to explore the biotechnological applications of GAs, including their use in floriculture, fruit production, and improving plant resilience under stress conditions, making them essential for sustainable agriculture.

Plant growth-promoting fungi improve tobacco yield and chemical components by reassembling rhizosphere fungal microbiome and recruiting probiotic taxa

BackgroundTobacco production faces ongoing challenges due to soil degradation, leading to a persistent decline in yield. Plant growth-promoting fungi (PGPF) have been recognized as an environmentally friendly agricultural strategy. However, many commercial PGPF products exhibit instability due to insufficient environmental compatibility.ResultsIn this study, Penicillium sp. PQxj3 was isolated and assessed for its potential to enhance tobacco productivity under field conditions. The results demonstrated that Penicillium sp. PQxj3 treatment significantly promoted the tobacco growth and improved the crop yield. The height of tobacco in Penicillium sp. PQxj3 treatment group significantly increased by 50.19% and 24.05% compared with CK at exuberant and maturity period (P < 0.05). The average yield of tobacco significantly increased by 36.16% compared to CK (P < 0.05). Fungal microbiome analysis revealed that phylogenetically similar probiotic taxa were recruited by Penicillium sp. PQxj3 and reassembled tobacco rhizosphere fungal microbiome. The key chemical indicators of tobacco such as alkaloid, total sugar, and phosphorus were significantly enhanced in Penicillium sp. PQxj3 treatment. The recruited probiotic taxa (Penicillium brasilianum, Penicillium simplicissimum, Penicillium macrosclerotiorum and Penicillium senticosum) were significantly associated with alkaloid, total sugar etc. (P < 0.05), which were identified as the key drivers for improving the chemical components of tobacco. Transcriptome analysis indicated that Penicillium sp. PQxj3 promoted up-regulation of key functional genes involved in alkaloid, indoleacetic, and gibberellin biosynthesis pathways.ConclusionIn summary, this study assessed the biopromotion mechanism of PGPF Penicillium sp. PQxj3 linking chemical traits, rhizosphere fungal microbiome, and transcriptome profiling. The findings provide a fundamental basis and a sustainable solution for developing fungal fertilizers to enhance agricultural sustainability.

Histological, Transcriptomic, and Functional Analyses Reveal the Role of Gibberellin in Bulbil Development in Lilium lancifolium

Lily bulbils, advantageous axillary organs used for asexual reproduction, have an underexplored developmental mechanism. Gibberellins are known to participate in bulbil development, but the regulatory mechanisms remain unclear. In this study, exogenous gibberellin (GA3) significantly increased the bulbil length, width, and weight by raising the endogenous gibberellin levels and elongating the scale cells. Transcriptomic analysis identified LlGA20ox2, a key gibberellin biosynthesis gene, which was upregulated during bulbil development and significantly responsive to GA3 treatment. Given the similarities in bulbil and bulblet development, we determined the roles of LlGA20ox2 using a bulblet system. Silencing LlGA20ox2 in bulblets inhibited development by reducing the cell length, while overexpression increased the bulblet length and width. In the gibberellin signaling pathway, we identified two key genes, LlGID1C and LlCIGR2. Silencing these genes resulted in phenotypes similar to LlGA20ox2, inhibiting bulblet development. Further transcriptomic analysis revealed that gibberellin-responsive genes were enriched in the glucuronate pathway, pentose phosphate pathway and galactose metabolism pathways. Most of these differentially expressed genes responded to gibberellin and were highly expressed in later stages of bulbil development, suggesting their involvement in gibberellin-regulated bulbil growth. In conclusion, we preliminarily explored the mechanisms of gibberellin regulation in bulbil development, offering significant commercial potential for new lily reproductive organs.

GW3, encoding a member of the P450 subfamily, controls grain width by regulating the GA4 content in spikelets of rice (Oryza sativa L.).

A stable QTL, GW3, controlling grain width was identified in two populations. Its causal gene LOC_Os03g04680 was verified by gene-based haplotype analysis, expression analysis, gene knockout and complementation transgenic tests. Grain width (GW) is one of the key traits affecting grain size and determines grain yield and appearance quality in rice. Mining gene loci and elite alleles controlling GW is necessary. The GW phenotypes of the two populations were investigated in three environments, which showed abundant phenotypic variation. GW3, encoding a P450 subfamily protein, was identified and validated as a causal gene by gene-based haplotype analysis, expression analysis, gene knockout and complementation transgenic tests. The accessions with large GW values had high gene expression levels. In addition, the GW of the accessions with the GG allele was significantly greater than that of the accessions with the AA allele. The Hap 1 and Hap 3 were identified as elite haplotypes, which can increase GW. The expression levels of OsKO1, OsGA3ox1, OsGA20ox1 and OsGA20ox2 in the young panicle of A7444 were significantly greater than those in the young panicle of the mutants, indicating that GW3 may be involved in the gibberellins (GA) biosynthesis pathway to regulate GW. GA4 content detection and electron scanning analysis revealed that GA4 regulates GW by affecting glume cell size. These results provide new insights for studying the genetic mechanism of rice GW and provide a material basis for breeding high-yield rice varieties.

Characterization of the gibberellic oxidase gene SdGA20ox1 in Sophora davidii (Franch.) skeels and interaction protein screening.

Gibberellin 20-oxidases (GA20oxs) are multifunctional enzymes involved in regulating gibberellin (GA) biosynthesis and controlling plant growth. We identified and characterized the GA20ox1 gene in a plant height mutant of Sophora davidii, referred to as SdGA20ox1. This gene was expressed in root, stem, and leaf tissues of the adult S. davidii plant height mutant, with the highest expression observed in the stem. The expression of SdGA20ox1 was regulated by various exogenous hormones. Overexpression of SdGA20ox1 in Arabidopsis resulted in significant elongation of hypocotyl and root length in seedlings, earlier flowering, smaller leaves, reduced leaf chlorophyll content, lighter leaf color, a significant increase in adult plant height, and other phenotypes. Additionally, transgenic plants exhibited a substantial increase in biologically active endogenous GAs (GA1, GA3, and GA4) content, indicating that overexpression of SdGA20ox1 accelerates plant growth and development. Using a yeast two-hybrid (Y2H) screen, we identified two SdGA20ox1-interacting proteins: the ethylene receptor EIN4 (11430582) and the rbcS (11416005) protein. These interactions suggest a potential regulatory mechanism for S. davidii growth. Our findings provide new insights into the role of SdGA20ox1 and its interacting proteins in regulating the growth and development of S. davidii.

The BnaBPs gene regulates flowering time and leaf angle in Brassica napus.

The flowering time and plant architecture of Brassica napus were significantly associated with yield. In this study, we found that the BREVIPEDICELLUS/KNAT1(BP) gene regulated the flowering time and plant architecture of B. napus. However, the precise regulatory mechanism remains unclear. We cloned two homologous BP genes, BnaBPA03 and BnaBPC03, from B. napus Xiaoyun. The protein sequence analysis showed two proteins containing conserved domains KNOX I, KNOX II, ELK, and HOX of the KONX protein family. The CRISPR/Cas9 knockout lines exhibited early budding and flowering time, coupled with floral organ abscission earlier and a larger leaf angle. On the contrary, overexpression plants displayed a phenotype that was the inverse of these characteristics. Furthermore, we observed upregulation of gibberellin and ethylene biosynthesis genes, as well as floral integrator genes in knocked-out plants. The results revealed that BnaBPs play a role in flowering time, floral organ abscission, and leaf angle as well as germination processes mediated. Additionally, BnaBPs exerted an impact on the biosynthesis pathways of ethylene and GA.

OsMBF1a Facilitates Seed Germination by Regulating Biosynthesis of Gibberellic Acid and Abscisic Acid in Rice.

Seed germination is a pivotal stage in the plant life cycle, orchestrated by a myriad of internal and external factors, notably plant hormones. The underlying molecular mechanisms governing rice seed germination remain largely unelucidated. Herein, we uncover OsMBF1a as a crucial regulatory factor that employs a dual strategy to promote seed germination: positively activating genes involved in gibberellin (GA) biosynthesis pathways, while negatively regulating key genes responsible for abscisic acid (ABA) synthesis. Furthermore, OsMBF1a modulates the endogenous levels of ABA and GA in rice seeds, reinforcing its central role in the germination process. The expression of ZmMBF1a and ZmMBF1b, the homologous genes in maize, in rice seeds similarly affects germination, indicating the conserved functionality of MBF1 family genes in regulating seed germination. This study provides novel insights into the molecular mechanisms underlying rice seed germination and underscores the significance of MBF1 family genes in plant growth and development.

Overexpression of two DELLA subfamily genes MiSLR1 and MiSLR2 from mango promotes early flowering and enhances abiotic stress tolerance in Arabidopsis

Gibberellic acids (GAs) are a group of endogenous phytohormones that play important roles in plant growth and development. SLENDER RICE (SLR) serves as a vital component of the DELLA gene family, which plays an irreplaceable role in regulating plant flowering and height, as well as stress responses. SLR gene has not been reported in mango, and its function is unknown. In present study, two DELLA subfamily genes MiSLR1 and MiSLR2 were identified from mango. MiSLR1 and MiSLR2 were highly expressed in the stems of the juvenile stage, but were expressed at a low level in flower buds and flowers. Gibberellin treatment could up-regulate the expression of MiSLR1 and MiSLR2 genes, but gibberellin biosynthesis inhibitor prohexadione-calcium (Pro-Ca) and paclobutrazol (PAC) treatments significantly down-regulated the expression of MiSLR1, while MiSLR2 was up-regulated. The expression levels of MiSLR1 and MiSLR2 were up-regulated under both salt and drought treatments. Overexpression of MiSLR1 and MiSLR2 genes significantly resulted early flowering in transgenic Arabidopsis and significantly up-regulated the expression levels of endogenous flower-related genes, such as SUPPRESSOR OF CONSTANS1 (SOC1), APETALA1 (AP1), and FRUITFULL (FUL). Interestingly, MiSLR1 significantly reduced the height of transgenic plants, while MiSLR2 gene increased. Overexpression of MiSLR1 and MiSLR2 increased seed germination rate, root length and survival rate of transgenic plants under salt and drought stress. Physiological and biochemical detection showed that the contents of proline (Pro) and superoxide dismutase (SOD) were significantly increased, while the contents of malondialdehyde (MDA) and H2O2 were significantly decreased. Additionally, protein interaction analysis revealed that MiSLR1 and MiSLR2 interacted with several flowering-related and GA-related proteins. The interaction between MiSLR with MiGF14 and MiSOC1 proteins was found for the first time. Taken together, the data showed that MiSLR1 and MiSLR2 in transgenic Arabidopsis both regulated the flowering time and plant height, while also acting as positive regulators of abiotic stress responses.

NADP-malic Enzyme OsNADP-ME2 Modulates Plant Height Involving in Gibberellin Signaling in Rice

Plants NADP-malic enzymes (NADP-MEs) act as a class of oxidative decarboxylase to mediate malic acid metabolism in organisms. Despite NADP-MEs have been demonstrated to play pivotal roles in regulating diverse biological processes, the role of NADP-MEs involving in plant growth and development remains rarely known. Here, we characterized the function of rice cytosolic OsNADP-ME2 in regulating plant height. The results showed that RNAi silencing and knock-out of OsNADP-ME2 in rice results in a dwarf plant structure, associating with significant expression inhibition of genes involving in phytohormone Gibberellin (GA) biosynthesis and signaling transduction, but with up-regulation for the expression of GA signaling suppressor SLR1. The accumulation of major bioactive GA1, GA4 and GA7 are evidently altered in RNAi lines, and exogenous GA treatment compromises the dwarf phenotype of OsNADP-ME2 RNAi lines. RNAi silencing of OsNADP-ME2 also causes the reduction of NADP-ME activity associating with decreased production of pyruvate. Thus, our data revealed a novel function of plant NADP-MEs in modulation of rice plant height through regulating bioactive GAs accumulation and GA signaling, and provided a valuable gene resource for rice plant architecture improvement.

Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades.

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

The Role of BrKS in Leafy Head Formation Was Confirmed by Two Allelic Mutants of Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Considering that the presence of a leafy head is a key morphological characteristic that determines the yield and quality of Chinese cabbage, identifying the major genes regulating the formation of a leafy head is crucial for variety improvement. A heading-related gene, BrKS, was previously predicted from a non-heading mutant, nhm1, derived from a heading variety, which encodes a key enzyme involved in gibberellin biosynthesis. Here, another mutant, nhm2, was identified from the same EMS-mutagenized population, and the phenotype of nhm2 was consistent with that of nhm1. We crossed mutants nhm1 and nhm2, and their F1 plants exhibited the mutant phenotype, which indicated that their mutant genes were allelic. A single non-synonymous mutation in the fourth exon of BrKS in mutant nhm1 and another single non-synonymous mutation in the tenth exon of BrKS in mutant nhm2. The same gene mutation in mutants nhm1 and nhm2 produced a similar non-heading phenotype, which confirmed the role of BrKS in the leafy head formation of Chinese cabbage. RNA-Seq analysis indicated that a transcription factor gene, BrERF1A, which is associated with leaf development, significantly down-regulated expression in mutant nhm1, and after the mutant was treated with GA3, the expression level of BrERF1A was recovered, which indicated that BrKS might be involved in leafy head formation through regulating the expression level of BrERF1A. Our findings provide important clues for revealing the molecular mechanism of leafy head formation in Chinese cabbage.

Insights into the ameliorative effect of ZnONPs on arsenic toxicity in soybean mediated by hormonal regulation, transporter modulation, and stress responsive genes.

Arsenic (As) contamination of agricultural soils poses a serious threat to crop productivity and food safety. Zinc oxide nanoparticles (ZnONPs) have emerged as a potential amendment for mitigating the adverse effects of As stress in plants. Soybean crop is mostly grown on marginalized land and is known for high accumulation of As in roots than others tissue. Therefore, this study aimed to elucidate the underlying mechanisms of ZnONPs in ameliorating arsenic toxicity in soybean. Our results demonstrated that ZnOB significantly improved the growth performance of soybean plants exposed to arsenic. This improvement was accompanied by a decrease (55%) in As accumulation and an increase in photosynthetic efficiency. ZnOB also modulated hormonal balance, with a significant increase in auxin (149%), abscisic acid (118%), gibberellin (160%) and jasmonic acid content (92%) under As(V) stress assuring that ZnONPs may enhance root growth and development by regulating hormonal signaling. We then conducted a transcriptomic analysis to understand further the molecular mechanisms underlying the NPs-induced As(V) tolerance. This analysis identified genes differentially expressed in response to ZnONPs supplementation, including those involved in auxin, abscisic acid, gibberellin, and jasmonic acid biosynthesis and signaling pathways. Weighted gene co-expression network analysis identified 37 potential hub genes encoding stress responders, transporters, and signal transducers across six modules potentially facilitated the efflux of arsenic from cells, reducing its toxicity. Our study provides valuable insights into the molecular mechanisms associated with metalloid tolerance in soybean and offers new avenues for improving As tolerance in contaminated soils.

A multifaceted crosstalk between brassinosteroid and gibberellin regulates the resistance of cucumber to Phytophthora melonis.

Cucumber plants are highly susceptible to the hemibiotroph oomycete Phytophthora melonis. However, the mechanism of resistance to cucumber blight remains poorly understood. Here, we demonstrated that cucumber plants with impairment in the biosynthesis of brassinosteroids (BRs) or gibberellins (GAs) were more susceptible to P. melonis. By contrast, increasing levels of endogenous BRs or exogenously application of 24-epibrassinolide enhanced the resistance of cucumber plants against P. melonis. Furthermore, we found that both knockout and overexpression of the BR biosynthesis gene CYP85A1 reduced the endogenous GA3 content compared with that of wild-type plants under the condition of inoculation with P. melonis, and the enhancement of disease resistance conferred by BR was inhibited in plants with silencing of the GA biosynthetic gene GA20ox1 or KAO. Together, these findings suggest that GA homeostasis is an essential factor mediating BRs-induced disease resistance. Moreover, BZR6, a key regulator of BR signaling, was found to physically interact with GA20ox1, thereby suppressing its transcription. Silencing of BZR6 promoted endogenous GA biosynthesis and compromised GA-mediated resistance. These findings reveal multifaceted crosstalk between BR and GA in response to pathogen infection, which can provide a new approach for genetically controlling P. melonis damage in cucumber production.

Genome-Wide Identification and Expression Analysis of ent-kaurene synthase-like Gene Family Associated with Abiotic Stress in Rice.

Rice (Oryza sativa) is one of the most important crops for humans. The homologs of ent-kaurene synthase (KS) in rice, which are responsible for the biosynthesis of gibberellins and various phytoalexins, are identified by their distinct biochemical functions. However, the KS-Like (KSL) family's potential functions related to hormone and abiotic stress in rice remain uncertain. Here, we identified the KSL family of 19 species by domain analysis and grouped 97 KSL family proteins into three categories. Collinearity analysis of KSLs among Poaceae indicated that the KSL gene may independently evolve and OsKSL1 and OsKSL4 likely play a significant role in the evolutionary process. Tissue expression analysis showed that two-thirds of OsKSLs were expressed in various tissues, whereas OsKSL3 and OsKSL5 were specifically expressed in the root and OsKSL4 in the leaf. Based on the fact that OsKSL2 participates in the biosynthesis of gibberellins and promoter analysis, we detected the gene expression profiles of OsKSLs under hormone treatments (GA, PAC, and ABA) and abiotic stresses (darkness and submergence). The qRT-PCR results demonstrated that OsKSL1, OsKSL3, and OsKSL4 responded to all of the treatments, meaning that these three genes can be candidate genes for abiotic stress. Our results provide new insights into the function of the KSL family in rice growth and resistance to abiotic stress.

An orchestrated ethylene-gibberellin signaling cascade contributes to mesocotyl elongation and emergence of rice direct seeding.

A mechanized direct seeding of rice with less labor and water usage, has been widely adopted. However, this approach requires varieties that exhibit uniform seedling emergence. Mesocotyl elongation (ME) offers the main drive of fast emergence of rice seedlings from soils; nevertheless, its genetic basis remains unknown. Here, we identify a major rice quantitative trait locus Mesocotyl Elongation1 (qME1), an allele of the Green Revolution gene Semi-Dwarf1 (SD1), encoding GA20-oxidase for gibberellin (GA) biosynthesis. ME1 expression is strongly induced by soil depth and ethylene. When rice grains are direct-seeded in soils, the ethylene core signaling factor OsEIL1 directly promotes ME1 transcription, accelerating bioactive GA biosynthesis. The GAs further degrade the DELLA protein SLENDER RICE 1 (SLR1), alleviating its inhibition of rice PHYTOCHROME-INTERACTING FACTOR-LIKE13 (OsPIL13) to activate the downstream expansion gene OsEXPA4 and ultimately promote rice seedling ME and emergence. The ancient traits of long mesocotyl and strong emergence ability in wild rice and landrace were gradually lost in company with the Green Revolution dwarf breeding process, and an elite ME1-R allele (D349H) is found in some modern Geng varieties (long mesocotyl lengths) in northern China, which can be used in the direct seeding and dwarf breeding of Geng varieties. Furthermore, the ectopic and high expression of ME1 driven by mesocotyl-specific promoters resulted in rice plants that could be direct-seeded without obvious plant architecture or yield penalties. Collectively, we reveal the molecular mechanism of rice ME, and provide useful information for breeding new Green Revolution varieties with long mesocotyl suitable for direct-seeding practice.

Functional characterization of ent-kaurane-type diterpenoid synthases from Stellera chamaejasme

Sequential catalysis by ent-copalyl diphosphate(CPS) and ent-kaurene synthase(KS) is a critical step for plants to initiate the biosynthesis of gibberellin with geranylgeranyl pyrophosphate(GGPP) as the substrate. This study mined the transcriptome data of Stellera chamaejasme and cloned two key diterpene synthase genes, SchCPS and SchKS, involved in the gibberellin pathway. The two genes had the complete open reading frames of 2 595 bp and 1 701 bp, encoding two hydrophilic proteins composed of 864 and 566 amino acid residues and with the relative molecular mass of 97.9 kDa and 64.6 kDa and the theoretical isoelectric points of 5.61 and 6.12, respectively. Sequence comparison and phylogenetic tree showed that SchCPS contained LHS, PNV, and DxDD motifs conserved in the CPS family and was categorized in the TPS-c subfamily, while SchKS contained DDxxD, NSE/DTE and PIx motifs conserved in the KS family and was categorized in the TPS-e subfamily. Functional validation showed that SchCPS catalyzed the protonation and cyclization of GGPP to ent-CPP, while SchKS acted on ent-CPP dephosphorylation and re-cyclization to ent-kaurene. In this study, the full-length sequences of SchCPS and SchKS were cloned and functionally verified for the first time, which not only enriched the existing CPS and KS gene libraries but also laid a foundation for the cloning and biosynthesis pathway analysis of more genes involved in the synthesis of active components in S. chamaejasme.

Inhibition of flowering by gibberellins in the woody plant Jatropha curcas is restored by overexpression of JcFT

Jatropha curcas (J. curcas) is a perennial oil-seed plant with vigorous vegetative growth but relatively poor reproductive growth and low seed yield. Gibberellins (GAs) promotes flowering in most annual plants but inhibits flowering in many woody plants, including J. curcas. However, the underlying mechanisms of GA inhibits flowering in perennial woody plants remain unclear. Here, we found that overexpression of the GA biosynthesis gene JcGA20ox1 inhibits flowering in J. curcas and in J. curcas × J. integerrima hybrids. Consistent with this finding, overexpression of the GA catabolic gene JcGA2ox6 promotes flowering in J. curcas. qRTPCR revealed that inhibits floral transition by overexpressing JcGA20ox1 resulted from a decrease in the expression of JcFT and other flowering-related genes, which was restored by overexpressing JcFT in J. curcas. Overexpression of JcGA20ox1 or JcGA2ox6 reduced seed yield, but overexpression of JcFT significantly increased seed yield. Furthermore, hybridization experiments showed that the reduction in seed yield caused by overexpression of JcGA20ox1 or JcGA2ox6 was partially restored by the overexpression of JcFT. In addition, JcGA20ox1, JcGA2ox6 and JcFT were also found to be involved in the regulation of seed oil content and endosperm development. In conclusion, our study revealed that the inhibitory effect of GA on flowering is mediated through JcFT and demonstrated the effects of JcGA20ox1, JcGA2ox6 and JcFT on agronomic traits in J. curcas. This study also indicates the potential value of GA metabolism genes and JcFT in the breeding of new varieties of woody oil-seed plants.

The Short Inflorescence Mutation in Diploid Strawberry Fragaria vesca Affects Inflorescence Architecture and Runner Elongation

Mutants are useful for determining the genes that underlie a given trait. This information is highly useful for developing molecular markers for breeding and is the foundational knowledge required for future genomic crop improvements. The dessert strawberry, Fragaria ×ananassa, is a valuable crop with high potential for increased use in controlled environment agriculture. The genome of the woodland strawberry Fragaria vesca is the dominant genome of the four diploid strawberry subgenomes that contribute to the octoploid F. ×ananassa genome. F. vesca is therefore a useful reference system for determining gene function and should be a useful source of gene diversity for breeding of F. ×ananassa. Chemical mutagenesis of the inbred F. vesca line H4 F7-3 resulted in one M2 line with a smaller stature overall and which produces flowers on very short peduncles close to the crown. This line was named short inflorescence (sin). The sin phenotype results from a single gene recessive mutation that is pleiotropic in that the mutation also affects internode lengths of runners as well as petiole elongation of sin plants. Microscopic characterization revealed that sin peduncles are most likely short because of a failure of cells to elongate. Inflorescences, runners, and petioles of sin plants were found to elongate in response to exogenous gibberellin, indicating that sin could be a gibberellin biosynthesis or transport mutant. A brief characterization of sin plants is presented to facilitate collaborative studies of the line.

Bifunctional transcription factors SlERF.H5 and H7 activate cell wall and repress gibberellin biosynthesis genes in tomato via a conserved motif

The plant cell wall is a dynamic structure that plays an essential role in development, but the mechanism regulating cell wall formation remains poorly understood. We demonstrate that two transcription factors, SlERF.H5 and SlERF.H7, control cell wall formation and tomato fruit firmness in an additive manner. Knockout of SlERF.H5, SlERF.H7, or both genes decreased cell wall thickness, firmness, and cellulose contents in fruits during early development, especially in double-knockout lines. Overexpressing either gene resulted in thicker cell walls and greater fruit firmness with elevated cellulose levels in fruits but severely dwarf plants with lower gibberellin contents. We further identified that SlERF.H5 and SlERF.H7 activate the cellulose biosynthesis gene SlCESA3 but repress the gibberellin biosynthesis gene GA20ox1. Moreover, we identified a conserved LPL motif in these ERFs responsible for their activities as transcriptional activators and repressors, providing insight into how bifunctional transcription factors modulate distinct developmental processes.

EjGASA6 promotes flowering and root elongation by enhancing gibberellin biosynthesis

The Gibberellic Acid-stimulated Arabidopsis (GASA) gene family is involved in the regulation of gene expression and plant growth, development, and stress responses. To investigate the function of loquat GASA genes in the growth and developmental regulation of plants, a loquat EjGASA6 gene homologous to Arabidopsis AtGASA6 was cloned. EjGASA6 expression was induced by gibberellin, and ectopic transgenic plants containing this gene exhibited earlier bloom and longer primary roots since these phenotypic characteristics are related to higher gibberellin content. Transcriptome analysis and qRT-PCR results showed that the expression levels of GA3ox1 and GA20ox1, which encode key enzymes in gibberellin biosynthesis, were significantly increased. Furthermore, we confirmed that EjGASA6 could promote the expression of GA20ox1 via the luciferase reporter system. Overall, our results suggest that EjGASA6 promotes blooming and main-root elongation by positively regulating gibberellin biosynthesis. These findings broaden our understanding of the role of GASAs in plant development and growth, and lay the groundwork for future research into the functions of EjGASA6 in regulating loquat growth and development.