GA20ox Genes Research Articles

Overexpression of the Poa pratensis GA2ox gene family significantly reduced the plant height of transgenic Arabidopsis thaliana and Poa pratensis

Gibberellin (GAs) is an important plant hormone that plays a key role in plant growth and development. Gibberellin 2-oxidase (GA2ox) catalyzes the inactivation of biologically active GA or their direct precursors. In this study, five GA2ox genes were isolated from the wild type Poa pratensis ‘Baron’, named PpGA2ox3, PpGA2ox4, PpGA2ox5, PpGA2ox8, and PpGA2ox9. Phylogenetic tree analysis showed that PpGA2ox3, PpGA2ox4, PpGA2ox5, and PpGA2ox8 belong to class I GA2ox genes, while PpGA2ox9 belongs to class III GA2ox genes. They expressed in all tissues of Poa pratensis, in each plant tissue and growth stage, the expression patterns were different. After GA3 spraying treatment, the expression of each gene showed different patterns. Subcellular localization showed that PpGA2ox3 was located in chloroplasts, while PpGA2ox5 and PpGA2ox9 were located in the cytoplasm. When PpGA2ox3 and PpGA2ox9 were overexpressed in Arabidopsis thaliana, they all led to a typical dwarf phenotype, as well as low plant height, small leaves and late flowering. Similarly, when they overexpressed in P. pratensis, the transgenic plants also exhibited a dwarf phenotype with a lower leaf length/width ratio. Hormone analysis suggested that these dwarfing traits might be caused by a decrease in GA4 content. These studies indicated that the PpGA2ox gene family played an important role in studying the mechanism of plant dwarfism and also had the potential to become important genes for the breeding of P. pratensis.

Functional characterization of WsPR-1 reveals its interplay with cytokinin and gibberellin signaling pathways

Pathogenesis-related protein 1 (PR-1) is an antimicrobial protein involved in systemic acquired resistance (SAR) in plants, but its regulatory role and interactions with other pathways remain unclear. In this study, we functionally characterize WsPR-1 gene of Withania somnifera in Nicotiana tabacum to elucidate its role in plant defense, growth, and development. Interestingly, transgenic tobacco plants with increased levels of cytokinin (CK) and decreased gibberellins (GAs) exhibited stunted shoot growth, an underdeveloped root system, modified leaf morphology, reduced seed pod production, and delayed leaf senescence. Transcriptional analysis revealed that WsPR-1 overexpression downregulated the GA 20-oxidase (GA20ox) gene involved in GA biosynthesis while upregulating GA 2-oxidase (GA2ox), a GA catabolic enzyme. Moreover, transcript levels of FRUITFULL (FUL) and LEAFY (NFL2) flowering genes exhibited a decrease in WsPR-1 plants, which could explain the delayed flowering and reduced seed pod development in transgenic plants. Confocal microscopy confirmed increased lignin deposition in stem cross-sections of WsPR-1 transgenic plants, supported by gene expression analysis and lignin content quantification. Additionally, our findings also suggest the involvement of Knotted1-like homeobox (KNOX) gene in enhancing cytokinin levels. This study highlights PR-1's regulatory role in plant growth and development, with potential to boost crop yields and enhance resilience.

Physiological and transcriptome analysis of changes in endogenous hormone and sugar content during the formation of tender asparagus stems

Asparagus is a nutritionally dense stem vegetable whose growth and development are correlated with its quality and yield. To investigate the dynamic changes and underlying mechanisms during the elongation and growth process of asparagus stems, we documented the growth pattern of asparagus and selected stem segments from four consecutive elongation stages using physiological and transcriptome analyses. Notably, the growth rate of asparagus accelerated at a length of 25 cm. A significant decrease in the concentration of sucrose, fructose, glucose, and additional sugars was observed in the elongation region of tender stems. Conversely, the levels of auxin and gibberellins(GAs) were elevated along with increased activity of enzymes involved in sucrose degradation. A significant positive correlation existed between auxin, GAs, and enzymes involved in sucrose degradation. The ABA content gradually increased with stem elongation. The tissue section showed that cell elongation is an inherent manifestation of stem elongation. The differential genes screened by transcriptome analysis were enriched in pathways such as starch and sucrose metabolism, phytohormone synthesis metabolism, and signal transduction. The expression levels of genes such as ARF, GA20ox, NCED, PIF4, and otherswere upregulated during stem elongation, while DAO, GA2ox, and other genes were downregulated. The gene expression level was consistent with changes in hormone content and influenced the cell length elongation. Additionally, the expression results of RT-qPCR were consistent with RNA-seq. The observed variations in gene expression levels, endogenous hormones and sugar changes during the elongation and growth of asparagus tender stems offer valuable insights for future investigations into the molecular mechanisms of asparagus stem growth and development and provide a theoretical foundation for cultivation and production practices.

The BEL1-like homeodomain protein OsBLH4 regulates rice plant height, grain number, and heading date by repressing the expression of OsGA2ox1.

Gibberellins (GAs) play crucial roles in regulating plant architecture and grain yield of crops. In rice, the inactivation of endogenous bioactive GAs and their precursors by GA 2-oxidases (GA2oxs) regulates stem elongation and reproductive development. However, the regulatory mechanisms of GA2ox gene expression, especially in rice reproductive organs, are unknown. The BEL1-like homeodomain protein OsBLH4, a negative regulatory factor for the rice OsGA2ox1 gene, was identified in this study. Loss of OsBLH4 function results in decreased bioactive GA levels and pleiotropic phenotypes, including reduced plant height, decreased grain number per panicle, and delayed heading date, as also observed in OsGA2ox1-overexpressing plants. Consistent with the mutant phenotype, OsBLH4 was predominantly expressed in shoots and young spikelets; its encoded protein was exclusively localized in the nucleus. Molecular analysis demonstrated that OsBLH4 directly bound to the promoter region of OsGA2ox1 to repress its expression. Genetic assays revealed that OsBLH4 acts upstream of OsGA2ox1 to control rice plant height, grain number, and heading date. Taken together, these results indicate a crucial role for OsBLH4 in regulating rice plant architecture and yield potential via regulation of bioactive GA levels, and provide a potential strategy for genetic improvements of rice.

Genome-wide identification of GA2ox genes family and analysis of PbrGA2ox1-mediated enhanced chlorophyll accumulation by promoting chloroplast development in pear

BackgroundChlorophyll (Chl) is an agronomic trait associated with photosynthesis and yield. Gibberellin 2-oxidases (GA2oxs) have previously been shown to be involved in Chl accumulation. However, whether and how the PbrGA2ox proteins (PbrGA2oxs) mediate Chl accumulation in pear (Pyrus spp.) is scarce.ResultsHere, we aimed to elucidate the role of the pear GA2ox gene family in Chl accumulation and the related underlying mechanisms. We isolated 13 PbrGA2ox genes (PbrGA2oxs) from the pear database and identified PbrGA2ox1 as a potential regulator of Chl accumulation. We found that transiently overexpressing PbrGA2ox1 in chlorotic pear leaves led to Chl accumulation, and PbrGA2ox1 silencing in normal pear leaves led to Chl degradation, as evident by the regreening and chlorosis phenomenon, respectively. Meanwhile, PbrGA2ox1-overexpressing (OE) tobacco plants discernably exhibited Chl built-up, as evidenced by significantly higher Pn and Fv/Fm. In addition, RNA sequencing (RNA-seq), physiological and biochemical investigations revealed an increase in abscisic acid (ABA), methyl jasmonate (MeJA), and salicylic acid (SA) concentrations and signaling pathways; a marked elevation in reducing and soluble sugar contents; and a marginal decline in the starch and sucrose levels in OE plants. Interestingly, PbrGA2ox1 overexpression did not prominently affect Chl synthesis. However, it indeed facilitated chloroplast development by increasing chloroplast number per cell and compacting the thylakoid granum stacks. These findings might jointly contribute to Chl accumulation in OE plants.ConclusionOverall, our results suggested that GA2oxs accelerate Chl accumulation by stimulating chloroplast development and proved the potential of PbrGA2ox1 as a candidate gene for genetically breeding biofortified pear plants with a higher yield.

Diversity of Gibberellin 2-oxidase genes in the barley genome offers opportunities for genetic improvement

IntroductionGibberellin (GA) is a vital phytohormone in regulating plant growth and development. During the “Green Revolution”, modification of GA-related genes created semi-dwarfing phenotype in cereal crops but adversely affected grain weight. Gibberellin 2-oxidases (GA2oxs) in barley act as key catabolic enzymes in deactivating GA, but their functions are still less known. ObjectivesThis study investigates the physiological function of two HvGA2ox genes in barley and identifies novel semi-dwarf alleles with minimum impacts on other agronomic traits. MethodsVirus-induced gene silencing and CRISPR/Cas9 technology were used to manipulate gene expression of HvGA2ox9 and HvGA2ox8a in barley and RNA-seq was conducted to compare the transcriptome between wild type and mutants. Also, field trials in multiple environments were performed to detect the functional haplotypes. ResultsThere were ten GA2oxs that distinctly expressed in shoot, tiller, inflorescence, grain, embryo and root. Knockdown of HvGA2ox9 did not affect plant height, while ga2ox8a mutants generated by CRISPR/Cas9 increased plant height and significantly altered seed width and weight due to the increased bioactive GA4 level. RNA-seq analysis revealed that genes involved in starch and sucrose metabolism were significantly decreased in the inflorescence of ga2ox8a mutants. Furthermore, haplotype analysis revealed one naturally occurring HvGA2ox8a haplotype was associated with decreased plant height, early flowering and wider and heavier seed. ConclusionOur results demonstrate the potential of manipulating GA2ox genes to fine tune GA signalling and biofunctions in desired plant tissues and open a promising avenue for minimising the trade-off effects of Green Revolution semi-dwarfing genes on grain size and weight. The knowledge will promote the development of next generation barley cultivars with better adaptation to a changing climate.

Preliminary Study on the Formation Mechanism of Malformed Sweet Cherry (Prunus avium L.) Fruits in Southern China Using Transcriptome and Metabolome Data.

Gibberellin (GA) is an important plant hormone that is involved in various physiological processes during plant development. Sweet cherries planted in southern China have always encountered difficulty in bearing fruit. In recent years, gibberellin has successfully solved this problem, but there has also been an increase in malformed fruits. This study mainly explores the mechanism of malformed fruit formation in sweet cherries. By analyzing the synthesis pathway of gibberellin using metabolomics and transcriptomics, the relationship between gibberellin and the formation mechanism of deformed fruit was preliminarily determined. The results showed that the content of GA3 in malformed fruits was significantly higher than in normal fruits. The differentially expressed genes in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were mainly enriched in pathways such as "plant hormone signal transduction", "diterpenoid biosynthesis", and "carotenoid biosynthesis". Using Quantitative Real-Time Reverse Transcription PCR (qRT-PCR) analysis, the gibberellin hydrolase gene GA2ox and gibberellin synthase genes GA20ox and GA3ox were found to be significantly up-regulated. Therefore, we speculate that the formation of malformed fruits in sweet cherries may be related to the accumulation of GA3. This lays the foundation for further research on the mechanism of malformed sweet cherry fruits.

Transcriptomic analysis of alternative splicing events for different stages of growth and development in Sistan Yaghooti grape clusters

Sistan Yaghooti grape variety, despite characteristics such as early ripening, is vulnerable to cluster rot due to small berries and dense clusters. In this regard, AS may serve as a regulatory mechanism during developmental processes and in response to environmental signals. RNA-Seq analysis was performed to measure gene expression and the extent of AS events in the cluster growth and development stages of Sistan Yaghooti grape. The number of AS events increased during stages, suggesting that it contributes to the grapevine's adaptability to various stresses. In addition, DEG and DAS genes showed little overlap in cluster growth stages. Functional analysis of 19,194 DAS -gene sets showed that VIT_06s0004g06670 gene is involved in the activation of calcium channels (Ca2+) through the activation of 5 PLC biosynthetic pathways. Among the 27,229 DEG -sets, VIT_07s0005g05320 gene showed higher expression. Interestingly, this gene is involved in the synthesis of an EF -hand domain-containing protein capable of binding to Ca2+ by activating 4 biochemical pathways. These genes increase cytosolic Ca2+ concentration, enhancing plant stress tolerance and resistance to cracking. These results show that AS can respond independently to different types of stress. Among the other DAS genes, the GA2ox gene (VvGA2ox) showed an increase in AS events during cluster development. This gene is critical for initiating the degradation process of GA and plays a crucial role in different stages of seed development. Therefore, it is very likely that this gene is one of the main factors responsible for the density and seedlessness of Sistan Yaghooti grape.

Impact of water stress during reproductive development on seed dormancy in Bromus diandrus Roth and Lolium rigidum Gaudin

Context Bromus diandrus Roth and Lolium rigidum Gaudin are important weeds of cereal-based cropping systems of Australian agriculture. Adaptation to environmental stresses, protracted seed germination and herbicide resistance have made these weeds serious threats to crop production. Aims Studies were undertaken to determine the impact of moisture stress during reproductive development on the extent of seed dormancy and the expression of genes involved with gibberellic acid and abscisic acid synthesis. Methodology A pot study was undertaken at two locations, with two populations each of B. diandrus and L. rigidum. Water stress was applied from either the GS31 or GS60 stage until seed maturation, along with a well-watered treatment. Seeds of stressed vs well-watered treatments were assessed for seed dormancy and the expression of ABA1 and GA20ox genes using quantitative polymerase chain reaction. Results The seeds from GS31 treatment, where plants experienced the longest water stress, were most dormant in both weed species. Water stress treatments altered the expression of the GA20ox gene, which was correlated with the level of dormancy in seeds of B. diandrus and L. rigidum. Conclusions This investigation has provided clear evidence of the impact of water stress on seed dormancy and on expression of genes involved in regulating seed dormancy in these weed species. Implications As spring rainfall in the Australian agricultural landscape is highly variable, weeds are likely to experience variable levels of water stress during reproductive development, which in turn is likely to influence seed dormancy, weed seedling emergence and effectiveness of pre-sowing weed management next season.

Genome-wide identification and expression analysis of GA20ox and GA3ox genes during pod development in peanut.

Gibberellins (GAs) play important roles in regulating peanut growth and development. GA20ox and GA3ox are key enzymes involved in GA biosynthesis. These enzymes encoded by a multigene family belong to the 2OG-Fe (II) oxygenase superfamily. To date, no genome-wide comparative analysis of peanut AhGA20ox and AhGA3ox-encoding genes has been performed, and the roles of these genes in peanut pod development are not clear. A whole-genome analysis of AhGA20ox and AhGA3ox gene families in peanut was carried out using bioinformatic tools. The expression of these genes at different stage of pod development was analyzed using qRT-PCR. In this study, a total of 15 AhGA20ox and five AhGA3ox genes were identified in peanut genome, which were distributed on 14 chromosomes. Phylogenetic analysis divided the GA20oxs and GA3oxs into three groups, but AhGA20oxs and AhGA3oxs in two groups. The conserved pattern of gene structure, cis-elements, and protein motifs further confirmed their evolutionary relationship in peanut. AhGA20ox and AhGA3ox genes were differential expressed at different stages of pod development. The strong expression of AhGA20ox1/AhGA20ox4, AhGA20ox12/AhGA20ox15, AhGA3ox1 and AhGA3ox4/AhGA3ox5 in S1-stage indicated that these genes could have a key role in controlling peg elongation. Furthermore, AhGA20ox and AhGA3ox also showed diverse expression patterns in different peanut tissues including leaves, main stems, flowers and inflorescences. Noticeably, AhGA20ox9/AhGA20ox11 and AhGA3o4/AhGA3ox5 were highly expressed in the main stem, whereas the AhGA3ox1 and AhGA20ox10 were strongly expressed in the inflorescence. The expression levels of AhGA20ox2/AhGA20ox3, AhGA20ox5/AhGA20ox6, AhGA20ox7/AhGA20ox8, AhGA20ox13/AhGA20ox14 and AhGA3ox2/AhGA3ox3 were high in the flowers, suggesting their involvement in flower development. These results provide a basis for deciphering the roles of AhGA20ox and AhGA3ox in peanut growth and development, especially in pod development.

GA20ox Family Genes Mediate Gibberellin and Auxin Crosstalk in Moso bamboo (Phyllostachys edulis).

Moso bamboo (Phyllostachys edulis) is one of the fastest growing plants. Gibberellin (GA) is a key phytohormone regulating growth, but there are few studies on the growth of Moso bamboo regulated by GA. The gibberellin 20 oxidase (GA20ox) gene family was targeted in this study. Chromosomal distribution and collinearity analysis identified 10 GA20ox genes evenly distributed on chromosomes, and the family genes were relatively conservative in evolution. The genetic relationship of GA20ox genes had been confirmed to be closest in different genera of plants in a phylogenetic and selective pressure analysis between Moso bamboo and rice. About 1/3 GA20ox genes experienced positive selective pressure with segmental duplication being the main driver of gene family expansion. Analysis of expression patterns revealed that only six PheGA20ox genes were expressed in different organs of shoot development and flowers, that there was redundancy in gene function. Underground organs were not the main site of GA synthesis in Moso bamboo, and floral organs are involved in the GA biosynthesis process. The auxin signaling factor PheARF47 was located upstream of PheGA20ox3 and PheGA20ox6 genes, where PheARF47 regulated PheGA20ox3 through cis-P box elements and cis-AuxRR elements, based on the result that promoter analysis combined with yeast one-hybrid and dual luciferase detection analysis identified. Overall, we identified the evolutionary pattern of PheGA20ox genes in Moso bamboo and the possible major synthesis sites of GA, screened for key genes in the crosstalk between auxin and GA, and laid the foundation for further exploration of the synergistic regulation of growth by GA and auxin in Moso bamboo.

Identification of GA2ox Family Genes and Expression Analysis under Gibberellin Treatment in Pineapple (Ananas comosus (L.) Merr.).

Gibberellin (GAs) plays an important regulatory role in the development and growth of pineapple (Ananas comosus (L.) Merr.). Bioinformatics was used to confirm the differential expression of GA2 gibberellin oxidase gene AcGA2oxs in the pineapple genome, which laid the foundation for exploring its role in pineapple. In this study, 42 GA2ox genes (AcGA2oxs) were identified in the pineapple genome, named from AcGA2ox1 to AcGA2ox42, and divided into four groups according to phylogenetic analysis. We also analyzed the gene structure, conserved motifs and chromosome localization of AcGA2oxs. AcGA2oxs within the same group had similar gene structure and motifs composition. Collinear analysis and cis-element analysis provided the basis for understanding the evolution and function of GA2ox genes in pineapple. In addition, we selected different tissue parts to analyze the expression profile of AcGA2oxs, and the results show that 41 genes were expressed, except for AcGA2ox18. AcGA2ox18 may not be expressed in these sites or may be pseudogenes. qRT-PCR (real-time fluorescence quantitative PCR) was used to detect the relative expression levels of the GA2ox gene family under different concentrations of GA3 treatment, and it was found that AcGA2ox gene expression was upregulated in different degrees under GA3 treatment. These results provide useful information for further study on the evolution and function of the GA2ox family in pineapple.

In silico curation of QTL-rich clusters and candidate gene identification for plant height of bread wheat

Many genetic loci for wheat plant height (PH) have been reported, and 26 dwarfing genes have been catalogued. To identify major and stable genetic loci for PH, here we thoroughly summarized these functionally or genetic verified dwarfing loci from QTL linkage analysis and genome-wide association study published from 2003 to 2022. A total of 332 QTL, 270 GWAS loci and 83 genes for PH were integrated onto chromosomes according to their locations in the IWGSC RefSeq v2.1 and 65 QTL-rich clusters (QRC) were defined. Candidate genes in each QRC were predicted based on IWGSC Annotation v2.1 and the information on functional validation of homologous genes in other species. A total of 38 candidate genes were predicted for 65 QRC including three GA2ox genes in QRC-4B-IV, QRC-5A-VIII and QRC-6A-II (Rht24) as well as GA 20-oxidase 2 (TaSD1-3A) in QRC-3A-IV. These outcomes lay concrete foundations for map-based cloning of wheat dwarfing genes and application in breeding.

Jasmonate-mediated gibberellin catabolism constrains growth during herbivore attack in rice.

Plant defense against herbivores is costly and often associated with growth repression. The phytohormone jasmonate (JA) plays a central role in prioritizing defense over growth during herbivore attack, but the underlying mechanisms remain unclear. When brown planthoppers (BPH, Nilaparvata lugens) attack rice (Oryza sativa), growth is dramatically suppressed. BPH infestation also increases inactive gibberellin (GA) levels and transcripts of GA 2-oxidase (GA2ox) genes, 2 (GA2ox3 and GA2ox7) of which encode enzymes that catalyze the conversion of bioactive GAs to inactive GAs in vitro and in vivo. Mutation of these GA2oxs diminishes BPH-elicited growth restriction without affecting BPH resistance. Phytohormone profiling and transcriptome analyses revealed that GA2ox-mediated GA catabolism was enhanced by JA signaling. The transcript levels of GA2ox3 and GA2ox7 were significantly attenuated under BPH attack in JA biosynthesis (allene oxide cyclase [aoc]) or signaling-deficient (myc2) mutants. In contrast, GA2ox3 and GA2ox7 expression was increased in MYC2 overexpression lines. MYC2 directly binds to the G-boxes in the promoters of both GA2ox genes to regulate their expression. We conclude that JA signaling simultaneously activates defense responses and GA catabolism to rapidly optimize resource allocation in attacked plants and provides a mechanism for phytohormone crosstalk.

Conservation and divergence of expression of GA2-oxidase homeologs in apple (Malus x domestica Borkh.).

In domesticated apple (Malus x domestica Borkh.) and other woody perennials, floral initiation can be repressed by gibberellins (GAs). The associated mechanism is a major unanswered question in plant physiology, and understanding organismal aspects of GA signaling in apple has important commercial applications. In plants, the major mechanism for elimination of GAs and resetting of GA signaling is through catabolism by GA2-oxidases (GA2ox). We found that the GA2ox gene family in apple comprises 16 genes representing eight, clearly defined homeologous pairs, which were named as MdGA2ox1A/1B to MdGA2ox8A/8B. Expression of the genes was analyzed in the various structures of the spur, where flowers are initiated, as well as in various structures of seedlings over one diurnal cycle and in response to water-deficit and salt stress. Among the results, we found that MdGA2ox2A/2B dominated expression in the shoot apex and were strongly upregulated in the apex after treatment with exogenous GA3, suggesting potential involvement in repression of flowering. Several MdGA2ox genes also showed preferential expression in the leaf petiole, fruit pedicel, and the seed coat of developing seeds, potentially representing mechanisms to limit diffusion of GAs across these structures. In all contexts studied, we documented both concerted and distinct expression of individual homeologs. This work introduces an accessible woody plant model for studies of GA signaling, GA2ox gene regulation, and conservation/divergence of expression of homeologous genes, and should find application in development of new cultivars of apple and other tree fruits.

Heterologous functional analysis and expression patterns of gibberellin 2-oxidase genes of barley (Hordeum vulgare L.)

The level of bioactive gibberellins (GAs) in plants is regulated partly by their inactivation, mainly by the action of GA 2-oxidases (GA2oxs). This study identified three new GA2ox genes in barley: HvGA2ox1, HvGA2ox3 and HvGA2ox6. Analysis of their nucleotide and putative amino acid sequences revealed that they share high sequence identity with other plant GA2oxs and their corresponding proteins. Phylogenetic analysis revealed the HvGA2ox1, HvGA2ox3 and HvGA2ox6 belong to GA2ox structural classes II, I, and III, respectively. Feeding the HvGA2ox1 and HvGA2ox3 recombinant proteins with the C19-GAs, GA1 and GA20, resulted in the production of GA8 and GA29, respectively, with no product detected when they were fed with the C20-GA, GA12. Whereas the HvGA2ox6 recombinant protein was able to convert GA12 to GA110, and no product was detected when it was fed with GA1 or GA20. HvGA2ox1 and HvGA2ox3 were highly expressed in internodes and the endosperm of maturing seeds while HvGA2ox6 was predominantly expressed in the embryos. Salinity stress upregulated the expression of all three genes in seedling tissues. Our results indicate that HvGA2ox1, HvGA2ox3 and HvGA2ox6 encode functional GA2oxs that can regulate GA levels, and therefore growth and development of a barley plant, and its interaction with environment.

Genome-Wide Identification, Evolution and Expression Analyses of GA2ox Gene Family in Brassica napus L.

Gibberellin 2-oxidases (GA2ox) are important enzymes that maintain the balance of bioactive GAs in plants. GA2ox genes have been identified and characterized in many plants, but these genes were not investigated in Brassica napus. Here, we identified 31 GA2ox genes in B. napus and 15 of these BnGA2ox genes were distributed in the A and C subgenomes. Subcellular localization predictions suggested that all BnGA2ox proteins were localized in the cytoplasm, and gene structure analysis showed that the BnGA2ox genes contained 2–4 exons. Phylogenetic analysis indicated that BnGA2ox family proteins in monocotyledons and dicotyledons can be divided into four groups, including two C19-GA2ox and two C20-GA2ox clades. Group 4 is a C20-GA2ox Class discovered recently. Most BnaGA2ox genes had a syntenic relationship with AtGA2ox genes. BnaGA2ox genes in the C subgenome had experienced stronger selection pressure than genes in the A subgenome. BnaGA2ox genes were highly expressed in specific tissues such as those involved in growth and development, and most of them were mainly involved in abiotic responses, regulation of phytohormones and growth and development. Our study provided a valuable evolutionary analysis of GA2ox genes in monocotyledons and dicotyledons, as well as an insight into the biological functions of GA2ox family genes in B. napus.

A splicing site change between exon 5 and 6 of the nuclear-encoded chloroplast-localized HvYGL8 gene results in reduced chlorophyll content and plant height in barley.

The chloroplast is an important cellular organelle and metabolic hub, which is not only responsible for plant photosynthesis but is also involved in the de novo biosynthesis of pigments, fatty acids, and hormone metabolisms. Several genes that are responsible for rice leaf color variations have been reported to be directly or indirectly involved in chlorophyll biosynthesis and chloroplast development, whereas a few genes have been functionally confirmed to be responsible for leaf color changes in barley at the molecular level. In this study, we obtained a yellow leaf and dwarf ygl8 mutant from the progeny of Morex (a variety of barley) seeds treated with EMS. We performed bulked-segregant analysis (BSA) and RNA-seq analysis and targeted a UMP kinase encoding gene, YGL8, which generated a splicing site change between exon 5 and 6 of YGL8 due to a G to A single-nucleotide transition in the 5th exon/intron junction in the ygl8 mutant. The splicing site change between exon 5 and 6 of YGL8 had no effects on chloroplast subcellular localization but resulted in an additional loop in the UMP kinase domain, which might disturb the access of the substrates. On one hand, the splicing site change between exon 5 and 6 of YGL8 downregulated the transcriptional expression of chloroplast-encoded genes and chlorophyll-biosynthesis-related genes in a temperature-dependent manner in the ygl8 mutant. On the other hand, the downregulation of bioactive GA-biosynthesis-related GA20ox genes and cell-wall-cellulose-biosynthesis-related CesA genes was also observed in the ygl8 mutant, which led to a reduction in plant height. Our study will facilitate the understanding of the regulation of leaf color and plant height in barley.

Genome-Wide Identification, Evolution and Expression Analyses of GA2ox Gene Family in Brassica napus L.

Gibberellin 2-oxidases (GA2ox) are important enzymes that maintain the balance of bioactive GAs in plants. GA2ox genes have been identified and characterized in many plants, but these genes were not investigated in Brassica napus. Here, we identified 31 GA2ox genes in B. napus and 15 of these BnaGA2ox genes were distributed in the A and C subgenomes. Subcellular localization predictions suggested that all BnaGA2ox proteins were localized in the cytoplasm, and gene structure analysis showed that the BnaGA2ox genes contained 2–4 exons. Phylogenetic analysis indicated that BnGA2ox family proteins in monocotyledons and dicotyledons can be divided into four groups, including two C19-GA2ox and two C20-GA2ox clades. Group 4 is a C20-GA2ox Class discovered recently. Most BnaGA2ox genes had a syntenic relationship with AtGA2ox genes. BnaGA2ox genes in the C subgenome had experienced stronger selection pressure than genes in the A subgenome. BnaGA2ox genes were highly expressed in specific tissues such as those involved in growth and development, and most of them were mainly involved in abiotic responses, regulation of phytohormones and growth and development. Our study provided a valuable evolutionary analysis of GA2ox genes in monocotyledons and dicotyledons, as well as an insight into the biological functions of GA2ox family genes in B. napus.

Targeted Metabolic and Transcriptomic Analysis of Pinus yunnanensis var. pygmaea with Loss of Apical Dominance.

Pinus yunnanensis var. pygmaea demonstrates obvious loss of apical dominance, inconspicuous main trunk, which can be used as an ideal material for dwarfing rootstocks. In order to find out the reasons for the lack of apical dominance of P. pygmaea, endogenous phytohormone content determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and comparative transcriptomes were performed on the shoot apical meristem and root apical meristem of three pine species (P. massoniana, P. pygmaea, and P. elliottii). The results showed that the lack of CK and the massive accumulation of ABA and GA-related hormones may be the reasons for the loss of shoot apical dominance and the formation of multi-branching, the abnormal synthesis of diterpenoid biosynthesis may lead to the influence of GA-related synthesis, and the high expression of GA 2-oxidase (GA2ox) gene may be the cause of dwarfing. Weighted correlation network analysis (WGCNA) screened some modules that were highly expressed in the shoot apical meristem of P. pygmaea. These findings provided valuable information for identifying the network regulation of shoot apical dominance loss in P. pygmaea and enhanced the understanding of the molecular mechanism of shoot apical dominance growth differences among Pinus species.