Semi-dwarf Mutant Research Articles

BW312 Hordeum vulgare semi-dwarf mutant exhibits a shifted metabolic profile towards pathogen resistance.

Plant hormonal mutants, which do not produce or are insensitive to hormones, are often affected in their growth and development, but other metabolic rearrangements might be involved. A trade-off between growth and stress response is necessary for the plant survival. Here, we explore the metabolic profile and the pathogen resistance of a brassinosteroid-insensitive Hordeum vulgare L. semi-dwarf mutant, BW312. We investigate BW312 metabolism through a chemical enrichment analysis, confirming a shifted metabolic profile towards pathogen resistance. The effective pathogen resistance of the mutant was tested in presence of Pyrenophora teres and Fusarium graminearum. Four compound families were increased in the mutant (pyrrolidines, basic amino acids, alkaloids, monounsaturated fatty acids), while two compound families were decreased (pyrrolidinones, anthocyanins). Dipeptides were also altered (increased and decreased). BW312 displayed a better resistance to Pyrenophora teres in the earliest stage of infection with a 21.5% decrease of the lesion length 10days after infection. BW312 also exhibited a reduced lesion length (43.3%) and a reduced browning of the lesions (55.5%) when exposed to Fusarium graminearum at the seedling stage. The observed metabolomic shift strongly suggests that the BW312 semi-dwarf mutant is in a primed state, resulting in a standby state of alertness to pathogens.

Phenotypic characterization and genetic mapping of the semi-dwarf mutant sdw9 in maize.

In summary, we characterized a maize semi-dwarf mutant, sdw9, and successfully isolated the responsible gene, which encodes a GRAS protein, through a combination of map-based cloning and Re-sequencing (Re-seq). Our findings demonstrate that the candidate gene ZmGRAS42 regulates BR signaling genes, thereby influencing internode development. This regulatory function likely involves processes such as cell division, cell cycle regulation and cell wall synthesis. Favorable variations of ZmGRAS42 identified in this study may hold promise for the development of lodging-resistant maize cultivars suitable for high-density planting, contributing to the improvement of maize breeding programs. Plant height and lateral root angle are crucial determinants of plant architecture in maize (Zea mays) which are closely related to lodging resistance at high planting density. These traits are intricately regulated by various phytohormones. Mutations affecting hormone biosynthesis and signaling often lead to reduced yield alongside diminished plant height, posing challenges in breeding dwarf maize varieties. In this study, the maize mutant sdw9 was characterized, which displays shorter stature and altered lateral root angle compared to WT, while showing potential to increase planting density and improve overall yield despite a slight reduction in single-ear yield. Employing positional cloning coupled with Re-seq techniques, we pinpointed a transposon insertion in the candidate gene ZmGRAS42, which encodes a GRAS transcription factor involved in BR signaling in maize. Transcriptome analysis revealed that ZmGRAS42 orchestrates the expression of several known dwarfing genes such as D8, Br2, and Na2, along with genes associated with cell wall organization, cell division, and cell cycle regulation, notably Cesa4, Cesa7, and Cyc11. Furthermore, identification of favorable ZmGRAS42 haplotypes linked to reduced plant height offers novel avenues for maize breeding strategies. These findings not only hold the potential for enhancing maize lodging resistance but also for optimizing land utilization through high-density planting practices.

A maize semi-dwarf mutant reveals a GRAS transcription factor involved in brassinosteroid signaling.

Brassinosteroids (BR) and gibberellins (GA) regulate plant height and leaf angle in maize (Zea mays). Mutants with defects in BR or GA biosynthesis or signaling identify components of these pathways and enhance our knowledge about plant growth and development. In this study, we characterized three recessive mutant alleles of GRAS transcription factor 42 (gras42) in maize, a GRAS transcription factor gene orthologous to the DWARF AND LOW TILLERING (DLT) gene of rice (Oryza sativa). These maize mutants exhibited semi-dwarf stature, shorter and wider leaves, and more upright leaf angle. Transcriptome analysis revealed a role for GRAS42 as a determinant of BR signaling. Analysis of the expression consequences from loss of GRAS42 in the gras42-mu1021149 mutant indicated a weak loss of BR signaling in the mutant, consistent with its previously demonstrated role in BR signaling in rice. Loss of BR signaling was also evident by the enhancement of weak BR biosynthetic mutant alleles in double mutants of nana plant1-1 and gras42-mu1021149. The gras42-mu1021149 mutant had little effect on GA-regulated gene expression, suggesting that GRAS42 is not a regulator of core GA signaling genes in maize. Single-cell expression data identified gras42 expressed among cells in the G2/M phase of the cell cycle consistent with its previously demonstrated role in cell cycle gene expression in Arabidopsis (Arabidopsis thaliana). Cis-acting natural variation controlling GRAS42 transcript accumulation was identified by expression genome-wide association study (eGWAS) in maize. Our results demonstrate a conserved role for GRAS42/SCARECROW-LIKE 28 (SCL28)/DLT in BR signaling, clarify the role of this gene in GA signaling, and suggest mechanisms of tillering and leaf angle control by BR.

Molecular and physiological characterization of early semi-dwarf mutants of rice and localization of SNP variants in Sd1 locus generated through gamma radiation

Purpose The ‘Improved White Ponni’ (IWP) rice variety, which is susceptible to lodging, leading to yield losses. Our primary goal is to develop new rice lines with non-lodging traits, enhancing stem strength and resistance to adverse conditions. Additionally, we aim to improve yield-contributing agronomic traits, benefiting farmers, food security, and the environment. Our work contributes to scientific knowledge and addresses a significant issue in Southern Indian rice cultivation. Materials and Methods In the present study, early and semi-dwarf early mutants of IWP were developed without altering the native grain quality traits using gamma ray-mediated mutagenesis. The seeds (500) were irradiated with γ-rays after fixing the Lethal Dose 50 (LD50), and selection for semi-dwarfism and earliness was imposed on a large M2 population. The selected traits were confirmed by evaluating the M3 lines at morpho-physiological, biochemical, and molecular levels. Results The response of mutants to gibberellic acid has been studied, which identified responsive mutants as well as slow-responding mutant lines including IWP-11-2, IWP-48-2, IWP-50-11, and IWP-33-2. Agar plate assay indicated low α- amylase content in IWP-50-11, IWP-33-2, IWP-43-1, IWP-47-2, and IWP-18-1. The scanning electron microscopy demonstrated that the mutants displayed an increased cellular dimension in comparison to the wild type. In dwarf mutants, null alleles were observed for the SD1 gene-specific primers which depicts gene undergone mutation. Further sequencing revealed the presence of single nucleotide polymorphisms in the SD1 gene resulting in semi-dwarfism in the mutant IWP-D-1. Conclusions The impact of a defective gibberellic acid-mediated signaling pathway in mutants to produce a novel high-yielding and early maturing semi-dwarf rice variety.

Auxin plays a key role in nitrogen and plant density-modulated root growth and yield in different plant types of rapeseed

ContextWith the increasing global food and oil security problems, improvement in rapeseed (Brassica napus L.) yield become urgent. Moreover, previous studies rarely used the semi-dwarf and compact plant type of rapeseed to improve yield potential. ObjectiveHerein, we aimed to investigate the effects of different nitrogen application rates and plant density on root growth and yield-related traits using three genotypes with different plant types to clarify various regulatory mechanisms using semi-dwarf and compact plant type mutants to achieve high yield. MethodsSplit-split-plot experiments with three nitrogen application rates (N1: N2: N3, 120: 240: 360 kg ha−1) and three plant densities (D1: D2: D3, 15 × 104: 45 × 104: 75 × 104 plants·ha−1) were conducted during the three growing seasons (2019–2022) using semi-dwarf mutant HS5sca, and HS5 (wild type) as well as their F1 hybrid HS5+/sca. ResultsWith decreasing nitrogen application rate (N3 to N2), the expression level of IAA signal response genes BnaA07. GH3 and BnaA03. IAA13 was decreased in root, while increased in shoot at the early-flowering stage. Moreover, IAA content was decreased in roots and aboveground parts, whereas soluble sugar content of root bleeding sap was increased and volume of root bleeding sap was decreased in three genotypes at early-flowering stage. Additionally, nitrogen accumulation per plant and yield per plant was decreased, while population nitrogen accumulation and population yield were increased with decreasing nitrogen application rate in three studied genotypes. On the other side, with increasing plant density, the expression of BnaA07. GH3 and BnaA03. IAA13 genes were first increased and then decreased in root tissues. In addition, root surface area, the total volume of root bleeding sap, and nitrogen accumulation were decreased, which decreased dry matter and yield per plant. However, total root area, population nitrogen accumulation, and population yield in the three genotypes were increased, and yield was the highest at D2. The population yield of HS5sca, HS5+/sca, and HS5 achieved the largest increase of 26.0%, 10.3%, and 9.5% under N2D2 in 2019, 6.9%, 8.4%, and 4.7% under N3D2 in 2020, respectively, as compared to N3D1. Moreover, the morphological indices of HS5+/sca were greater than other genotypes, with the highest population yield. ConclusionsAppropriate nitrogen application rate with plant density optimized the root architecture and aboveground type of HS5+/sca that improved auxin level through affecting the downstream auxin-related genes, as well as improved dry matter accumulation and distribution, which increased yield potential. Compared with the two parents, F1 genotype HS5+/sca was suitable for nitrogen fertilizer (240 kg ha−1) and plant density (45–75 × 104 plants ha−1). Implications+ /sca heterozygous genotypes might promote root growth under low nitrogen application rate and high plant density. A strong root system is an important guarantee of high yield; thus, this heterozygous site could use to introduce excellent hybrids in rapeseed production to further improve root traits and optimize cultivation factors to increase seed yield.

Gibberellin metabolism and signaling.

Gibberellins (GAs) are plant hormones with a tetracyclic diterpenoid structure that are involved in various important developmental processes. Two GA-deficient mutants were isolated: a semidwarf mutant "sd1", which was found to have a defective GA20ox2 gene and was introduced to the world in a green revolution cultivar, and a severe dwarf allele of "d18", with a defective GA3ox2 gene. Based on the phenotypic similarity of d18, rice dwarf mutants were screened, further classifying them into GA-sensitive and GA-insensitive by applying exogenous GA3. Finally, GA-deficient rice mutants at 6 different loci and 3 GA signaling mutants (gid1, gid2, and slr1) were isolated. The GID1 gene encodes a GA nuclear receptor, and the GID1-DELLA (SLR1) system for GA perception is widely used in vascular plants. The structural characteristics of GID1 and GA metabolic enzymes have also been reviewed.

Genetic analysis and mapping of dwarf gene without yield penalty in a γ-ray-induced wheat mutant.

Plant height is one of the most important agronomic traits that affects yield in wheat, owing to that the utilization of dwarf or semi-dwarf genes is closely associated with lodging resistance. In this study, we identified a semi-dwarf mutant, jg0030, induced by γ-ray mutagenesis of the wheat variety 'Jing411' (wild type). Compared with the 'Jing411', plant height of the jg0030 mutant was reduced by 7%-18% in two years' field experiments, and the plants showed no changes in yield-related traits. Treatment with gibberellic acid (GA) suggested that jg0030 is a GA-sensitive mutant. Analysis of the frequency distribution of plant height in 297 F3 families derived from crossing jg0030 with the 'Jing411' indicated that the semi-dwarf phenotype is controlled by a major gene. Using the wheat 660K SNP array-based Bulked Segregant Analysis (BSA) and the exome capture sequencing-BSA assay, the dwarf gene was mapped on the long arm of chromosome 2B. We developed a set of KASP markers and mapped the dwarf gene to a region between marker PH1 and PH7. This region encompassed a genetic distance of 55.21 cM, corresponding to a physical distance of 98.3 Mb. The results of our study provide a new genetic resource and linked markers for wheat improvement in molecular breeding programs.

BnaC01.BIN2, a GSK3-like kinase, modulates plant height and yield potential in Brassica napus.

Using map-based cloning and transgenic transformation, we revealed that glycogen kinase synthase 3-like kinase, BnaC01.BIN2, modulates plant height and yield in rapeseed. The modification of plant height is one of the most important goals in rapeseed breeding. Although several genes that regulate rapeseed plant height have been identified, the genetics mechanisms underlying rapeseed plant height regulation remain poorly understood, and desirable genetic resources for rapeseed ideotype breeding are scarce. Here, we map-based cloned and functionally verified thatthe rapeseed semi-dominant gene, BnDF4, greatly affects rapeseed plant height. Specifically, BnDF4 encodes brassinosteroid(BR)-insensitive 2, a glycogen synthase kinase 3 primarily expressed in the lower internodes to modulate rapeseed plant height by blocking basal internode-cell elongation. Transcriptome data showed that several cell expansion-related genes involving auxin and BRs pathways were significantly downregulated in the semi-dwarf mutant. Heterozygosity in the BnDF4 allele results in small stature with no marked differences in other agronomic traits. Using BnDF4 in the heterozygous condition, the hybrid displayed strong yield heterosis through optimum intermediate plant height. Our results provide a desirable genetic resource for breeding semi-dwarf rapeseed phenotypes and support an effective strategy for breeding rapeseed hybrid varieties with strong yield heterosis.

BnaSD.C3 is a novel major quantitative trait locus affecting semi-dwarf architecture in Brassica napus

Plant height is a key plant architectural trait that affects the seed yield, harvest index and lodging resistance in Brassica napus L., although the genetic mechanisms affecting plant height remain unclear. Here, a semi-dwarf mutant, df34, was obtained by ethyl methanesulphonate-induced mutagenesis. Genetic analysis showed that the semi-dwarf phenotype is controlled by one semi-dominant gene, which was located on chromosome C03 using a bulked segregant analysis coupled with whole-genome sequencing, and this gene was named BnaSD.C3. Then BnaSD.C3 was fine-mapped to a 297.35-kb segment of the “Darmor-bzh” genome, but there was no potential candidate gene for the semi-dwarf trait underlying this interval. Furthermore, the interval was aligned to the Zhongshuang 11 reference genome. Finally, combining structural variation analysis, transcriptome sequencing, phytohormone analyses and gene annotation information, BnaC03G0466900ZS and BnaC03G0478900ZS were determined to be the most likely candidate genes affecting the plant height of df34. This study provides a novel major locus for breeding and new insights into the genetic architecture of plant height in B. napus.

A very-long-chain fatty acid synthesis gene, SD38, influences plant height by activating ethylene biosynthesis in rice.

As an important trait in crop breeding, plant height is associated with lodging resistance and yield. With the identification and cloning of several semi-dwarfing genes, increasing numbers of semi-dwarf cultivars have emerged, which has led to a 'green revolution' in rice (Oryza sativa) production. In this study, we identified a rice semi-dwarf mutant, semi-dwarf 38 (sd38), which showed significantly reduced cell length. SD38 encodes a fatty acid elongase, β-ketoacyl-CoA synthase, which is involved in the synthesis of very-long-chain fatty acids (VLCFAs). Expression analysis showed that SD38 was localized on the membrane of the endoplasmic reticulum, and was expressed in all analyzed tissues with differential abundance. The mutation of SD38 affected lipid metabolism in the sd38 mutant. A functional complementarity test in Saccharomyces cerevisiae indicated that SD38 was capable of complementing the deficiency of ELO3p activity in BY4741-elo3 knockout yeast cells by participating in the synthesis of C24:0 VLCFA. Significant changes were observed in the expression of genes involved in ethylene synthesis, which resulted in reduced content of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in the sd38 mutant. Exogenously supplied VLCFA (C24:0) increased the expression levels of OsACS3, OsACS4, and OsACO7 and the plant height of sd38 mutant seedlings, similar to the effect of exogenous application of ACC and ethephon. These results reveal a relationship among VLCFAs, ethylene biosynthesis, and plant height and improve our understanding of plant height development in crops.

Induction of Chlorophyll and Morphological Mutations through Gamma Ray in Traditional Aromatic Cultivar Tulaipanja

The induced mutation of the traditional aromatic cultivar may provide useful alternative or complement to natural variation which may be used directly in mutation breeding or as a source of germ plasm in hybridization programme. Induced mutations irradiated through gamma ray in aromatic cultivar Tulaipanja were studied for chlorophyll and other morphological characters in the M2 generation. The frequency of chlorophyll mutations was high in higher doses. Among the chlorophyll mutants studied, albina was the most frequent, followed by alboxantha, alboviridis, xantha, viridis and striata. The mutation efficiency and the mutagenic effectiveness of the mutagen is more in the lower dose. The semi-dwarf mutants were more prevalent followed by dwarf and semitall-I mutants. The number of height mutants is much more in lower dose than that of higher dose. Among the morphological mutants, a number of mutants with broom stick leaf and few mutants with grassy leaf, rolled leaf, striped leaf were obtained. Besides these, delayed flowering mutants were obtained in low frequency in both the doses while the early flowering mutants were obtained only in the lower dose. The desirable dwarf or semi-dwarf early flowering mutants may be utilized directly or for recombination breeding, whereas the high yielding lines screened may be used directly as aromatic cultivar provided if the performance in the later generation is good.

Cloning of a new allele of ZmAMP1 and evaluation of its breeding value in hybrid maize

Gene resources associated with plant stature and flowering time are invaluable for maize breeding. In this study, using an F2:3 population derived from a natural semi-dwarf mutant grmm and a normal inbred line Si 273, we identified a major pleiotropic QTL on the distal long arm of chromosome 1 (qPH1_dla), and found that qPH1_dla controlled plant height, flowering time, ear and yield traits. qPH1_dla was fine-mapped to a 16 kb interval containing ZmAMP1, which was annotated as a glutamate carboxypeptidase. Allelism tests using two independent allelic mutants confirmed that ZmAMP1 was the causal gene. Real-time quantitative PCR and genomic sequence analysis suggested that a nonsynonymous mutation at the 598th base of ZmAMP1 gene was the causal sequence variant for the dwarfism of grmm. This novel ZmAMP1 allele was named ZmAMP1_grmm. RNA sequencing using two pairs of near isogenic lines (NILs) showed that 84 up-regulated and 68 down-regulated genes in dwarf NILs were enriched in 15 metabolic pathways. Finally, introgression of ZmAMP1_grmm into Zhengdan 958 and Xianyu 335 generated two improved F1 lines. In field tests, they were semi-dwarf, early-flowering, lodging-resistant, and high-yielding under high-density planting conditions, suggesting that ZmAMP1_grmm is a promising Green Revolution gene for maize hybrid breeding.

OsFBK4, a novel GA insensitive gene positively regulates plant height in rice (Oryza Sativa L.)

Semi-dwarf is one of the most valuable agronomic characteristics for rice improvement programs because it affects lodging resistance and grain yield. In the present study, a semi-dwarf mutant, RE9586 , exhibits reduced plant height, panicle length and decreased grain yield. Scanning electron microscopic observation results showed that the longitudinal length of the uppermost internode of RE9586 significantly reduced, resulting in a semi-dwarf phenotype. Employing a MutMap-based strategy, LOC_Os02g11790 was preliminarily identified as the candidate gene, which encoded the F-box domain and kelch repeat-containing protein ( OsFBK4 ). A point mutation in the 3rd exon of OsFBK4 resulted in an amino acid change of 414 R→G that was subsequently confirmed by linkage analysis. Real time-PCR showed the OsFBK4 gene was predominantly expressed in the internode. The knockout lines of OsFBK4 by CRISPR/Cas9 showed a short plant height, while OsFBK4 overexpression lines recovered the phenotype of plant height. We have also demonstrated that the expressions of GA-signaling genes such as SRL1 , CIGR , GID1 , GID2 , D1 , and SPY showed clear differences in which SRL1 was down regulated, while other genes were up-regulated in RE9586 mutant. GA biosynthesis genes, OsKAO , OsGA3ox2 , and OsGA2ox2 , also displayed apparent differences in expression level. In addition, the OsFBK4 protein probably localized to the nucleus and plasma membrane. In conclusion, OsFBK4 regulates plant height involving in GA signaling, providing further insights into the mechanisms underlying the regulation of plant height in rice.

Narrow lpa1 Metaxylems Enhance Drought Tolerance and Optimize Water Use for Grain Filling in Dwarf Rice.

Rice cultivation needs extensive amounts of water. Moreover, increased frequency of droughts and water scarcity has become a global concern for rice cultivation. Hence, optimization of water use is crucial for sustainable agriculture. Here, we characterized Loose Plant Architecture 1 (LPA1) in vasculature development, water transport, drought resistance, and grain yield. We performed genetic combination of lpa1 with semi-dwarf mutant to offer the optimum rice architecture for more efficient water use. LPA1 expressed in pre-vascular cells of leaf primordia regulates genes associated with carbohydrate metabolism and cell enlargement. Thus, it plays a role in metaxylem enlargement of the aerial organs. Narrow metaxylem of lpa1 exhibit leaves curling on sunny day and convey drought tolerance but reduce grain yield in mature plants. However, the genetic combination of lpa1 with semi-dwarf mutant (dep1-ko or d2) offer optimal water supply and drought resistance without impacting grain-filling rates. Our results show that water use, and transports can be genetically controlled by optimizing metaxylem vessel size and plant height, which may be utilized for enhancing drought tolerance and offers the potential solution to face the more frequent harsh climate condition in the future.

The MSI1 member OsRBAP1 gene, identified by a modified MutMap method, is required for rice height and spikelet fertility

To explore the molecular mechanisms underlying plant height regulation, we isolated and characterized a stably inherited semi-dwarf mutant bgsd-2 from the ethane methyl sulfonate (EMS) mutant progeny of ‘Ping Tang Wild-type (PTWT)’, a rice (Oryza sativa ssp. japonica) landrace in Guizhou. Transcriptome sequencing and qRT-PCR analyses showed that a number of cellulose and lignin-related genes involved in cell wall biogenesis were substantially downregulated in bgsd-2. MutMap-based cloning revealed the occurrence of a single amino acid substitution in the LOC_Os01g51300 gene, belonging to the MSI1 (multicopy suppressor of IRA1) member OsRBAP1. The bgsd-2 mutation occurred in the 3rd exon of OsRBAP1, resulting in a nonsense mutation of a codon shift from glycine (G) to glutamic acid (E) at residue 65. Protein localization analysis uncovered that the OsRBAP1 gene encodes a nuclear-localized protein and that the mutation in bgsd-2 may affect the stability of the OsRBAP1 protein. The CRISPR/Cas9 system was used to switch off OsRBAP1 in PTWT to obtain the knockout mutant osrbap1, which exhibited a severe reduction in height and fertility. Cytological observations suggest that the dwarfism of osrabp1 may be caused by reduced cell size and numbers, and that male sterility may be due to abnormal microspore development. Transcriptome analysis revealed that OsRBAP1 defects can repress the expression of numerous essential genes, which regulate multiple developmental processes in plants. Altogether, our results suggest that OsRBAP1 plays an important role in the regulation of rice height and spikelet fertility.

Mapping of dwarfing QTL of Ari1327, a semi-dwarf mutant of upland cotton

BackgroundUpland Cotton (Gossypium hirsutum L.) has few cotton varieties suitable for mechanical harvesting. The plant height of the cultivar is one of the key features that need to modify. Hence, this study was planned to locate the QTL for plant height in a 60Co γ treated upland cotton semi-dwarf mutant Ari1327.ResultsInterestingly, bulk segregant analysis (BSA) and genotyping by sequencing (GBS) methods exhibited that candidate QTL was co-located in the region of 5.80–9.66 Mb at D01 chromosome in two F2 populations. Using three InDel markers to genotype a population of 1241 individuals confirmed that the offspring’s phenotype is consistent with the genotype. Comparative analysis of RNA-seq between the mutant and wild variety exhibited that Gh_D01G0592 was identified as the source of dwarfness from 200 genes. In addition, it was also revealed that the appropriate use of partial separation markers in QTL mapping can escalate linkage information.ConclusionsOverwhelmingly, the results will provide the basis to reveal the function of candidate genes and the utilization of excellent dwarf genetic resources in the future.

Comparative transcriptome analysis of the peanut semi-dwarf mutant 1 reveals regulatory mechanism involved in plant height.

Plant height is a fundamentally crucial agronomic trait to control crop growth and high yield cultivation. Several studies have been conducted on the understanding ofmolecular genetic bases of plant height in model plants and crops. However, the molecular mechanism underlying peanut plant height development is stilluncertain. In the present study, we created a peanut mutant library by fast neutron irradiation using peanut variety SH13 and identified a semi-dwarf mutant 1 (sdm1). At 84 DAP (days after planting), the main stem of sdm1 was only about 62% of SH13. The internode length of sdm1 hydroponic seedlings was found significantly shorter than that of SH13 at 14 DAP. In addition, the foliar spraying of exogenous IAA could partially restore the semi-dwarf phenotype of sdm1. Transcriptome data indicated that the differentially expressed genes (DEGs) between sdm1 and SH13 significantly enriched in diterpenoid biosynthesis, alpha-linolenic acid metabolism, brassinosteroid biosynthesis, tryptophan metabolism and plant hormone signal transduction. The expression trend of most of the genes involved in IAA and JA pathway showed significantly down- and up- regulation, which may be one of the key factors of the sdm1 semi-dwarf phenotype. Moreover, several transcription factorsand cell wall relatedgenes were expressed differentially between sdm1 and SH13. Conclusively, this research work not only provided important clues to unveil the molecular mechanism of peanut plant height regulation, but also presented basic materials for breeding peanut cultivars with ideal plant height.

Mapping of a major QTL controlling plant height using a high-density genetic map and QTL-seq methods based on whole-genome resequencing in Brassica napus.

Plant height is a crucial element related to plant architecture that influences the seed yield of oilseed rape (Brassica napus L.). In this study, we isolated a natural B. napus mutant, namely a semi-dwarf mutant (sdw-e), which exhibits a 30% reduction in plant height compared with Zhongshuang 11-HP (ZS11-HP). Quantitative trait locus sequencing (QTL-seq) was conducted using two extreme DNA bulks in F2 populations in Wuchang-2017 derived from ZS11-HP × sdw-e to identify QTLs associated with plant height. The result suggested that two QTL intervals were located on chromosome A10. The F2 population consisting of 200 individuals in Yangluo-2018 derived from ZS11-HP × sdw-e was used to construct a high-density linkage map using whole-genome resequencing. The high-density linkage map harbored 4323 bin markers and covered a total distance of 2026.52 cM with an average marker interval of 0.47 cM. The major QTL for plant height named qPHA10 was identified on linkage group A10 by interval mapping and composite interval mapping methods. The major QTL qPHA10 was highly consistent with the QTL-seq results. And then, we integrated the variation sites and expression levels of genes in the major QTL interval to predict the candidate genes. Thus, the identified QTL and candidate genes could be used in marker-assisted selection for B. napus breeding in the future.

Melon short internode (CmSi) encodes an ERECTA-like receptor kinase regulating stem elongation through auxin signaling

SummaryPlant height is one of the most important agronomic traits that directly determines plant architecture, and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lodging resistance and economic yield. At least four dwarf/semidwarf genes have been identified in different melon varieties, but none of them have been cloned, and little is known about the molecular mechanisms underlying internode elongation in melon. Here, we report map-based cloning and functional characterization of the first semidwarf gene short internode (Cmsi) in melon, which encodes an ERECTA-like receptor kinase regulating internode elongation. Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of the main stem during internode elongation. The expression level of CmSI was positively correlated with stem length in the different melon varieties examined. Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator of internode elongation in both species. Phytohormone quantitation and transcriptome analysis showed that the auxin content and the expression levels of a number of genes involved in the auxin signaling pathway were altered in the semidwarf mutant, including several well-known auxin transporters, such as members of the ABCB family and PIN-FORMED genes. A melon polar auxin transport protein CmPIN2 was identified by protein–protein interaction assay as physically interacting with CmSI to modulate auxin signaling. Thus, CmSI functions in an auxin-dependent regulatory pathway to control internode elongation in melon. Our findings revealed that the ERECTA family gene CmSI regulates stem elongation in melon through auxin signaling, which can directly affect polar auxin transport.

Systems Metabolic Alteration in a Semi-Dwarf Rice Mutant Induced by OsCYP96B4 Gene Mutation.

Dwarfism and semi-dwarfism are among the most valuable agronomic traits in crop breeding, which were adopted by the “Green Revolution”. Previously, we reported a novel semi-dwarf rice mutant (oscyp96b4) derived from the insertion of a single copy of Dissociator (Ds) transposon into the gene OsCYP96B4. However, the systems metabolic effect of the mutation is not well understood, which is important for understanding the gene function and developing new semi-dwarf mutants. Here, the metabolic phenotypes in the semi-dwarf mutant (M) and ectopic expression (ECE) rice line were compared to the wild-type (WT) rice, by using nuclear magnetic resonance (NMR) metabolomics and quantitative real-time polymerase chain reaction (qRT-PCR). Compared with WT, ECE of the OsCYP96B4 gene resulted in significant increase of γ-aminobutyrate (GABA), glutamine, and alanine, but significant decrease of glutamate, aromatic and branched-chain amino acids, and some other amino acids. The ECE caused significant increase of monosaccharides (glucose, fructose), but significant decrease of disaccharide (sucrose); induced significant changes of metabolites involved in choline metabolism (phosphocholine, ethanolamine) and nucleotide metabolism (adenosine, adenosine monophosphate, uridine). These metabolic profile alterations were accompanied with changes in the gene expression levels of some related enzymes, involved in GABA shunt, glutamate and glutamine metabolism, choline metabolism, sucrose metabolism, glycolysis/gluconeogenesis pathway, tricarboxylic acid (TCA) cycle, nucleotide metabolism, and shikimate-mediated secondary metabolism. The semi-dwarf mutant showed corresponding but less pronounced changes, especially in the gene expression levels. It indicates that OsCYP96B4 gene mutation in rice causes significant alteration in amino acid metabolism, carbohydrate metabolism, nucleotide metabolism, and shikimate-mediated secondary metabolism. The present study will provide essential information for the OsCYP96B4 gene function analysis and may serve as valuable reference data for the development of new semi-dwarf mutants.