SUMMARY
Floral patterns are unique to rice and contribute significantly to its reproductive success. SL1 encodes a C2H2 transcription factor that plays a critical role in flower development in rice, ...but the molecular mechanism regulated by it remains poorly understood. Here, we describe interactions of the SL1 with floral homeotic genes, SPW1, and DL in specifying floral organ identities and floral meristem fate. First, the sl1 spw1 double mutant exhibited a stamen‐to‐pistil transition similar to that of sl1, spw1, suggesting that SL1 and SPW1 may located in the same pathway regulating stamen development. Expression analysis revealed that SL1 is located upstream of SPW1 to maintain its high level of expression and that SPW1, in turn, activates the B‐class genes OsMADS2 and OsMADS4 to suppress DL expression indirectly. Secondly, sl1 dl displayed a severe loss of floral meristem determinacy and produced amorphous tissues in the third/fourth whorl. Expression analysis revealed that the meristem identity gene OSH1 was ectopically expressed in sl1 dl in the fourth whorl, suggesting that SL1 and DL synergistically terminate the floral meristem fate. Another meristem identity gene, FON1, was significantly decreased in expression in sl1 background mutants, suggesting that SL1 may directly activate its expression to regulate floral meristem fate. Finally, molecular evidence supported the direct genomic binding of SL1 to SPW1 and FON1 and the subsequent activation of their expression. In conclusion, we present a model to illustrate the roles of SL1, SPW1, and DL in floral organ specification and regulation of floral meristem fate in rice.
Significance Statement
The morphology of rice flowers is crucial for successful reproduction and grain yield. However, research on floral organ specification gene regulatory network (FOS‐GRN) in rice and other grass species is not as extensive as in Arabidopsis. In this study, we unveil the crucial role of the C2H2 zinc finger transcription factor SL1 in regulating flower organ development and floral meristem fate in rice. Our experimental evidence indicates that SL1 positively regulates the expression of SPW1, which, in turn, activates B‐class genes OsMADS2 and OsMADS4 to indirectly suppress DL expression, influencing the formation of floral organs. Additionally, we identify a cooperative role of SL1 and DL in terminating floral meristem fate.
Microwave-assisted extraction was applied to extract rutin; quercetin; genistein; kaempferol; and isorhamnetin from Flos Sophorae Immaturus. Six independent variables; namely; solvent type; particle ...size; extraction frequency; liquid-to-solid ratio; microwave power; and extraction time were examined. Response surface methodology using a central composite design was employed to optimize experimental conditions (liquid-to-solid ratio; microwave power; and extraction time) based on the results of single factor tests to extract the five major components in Flos Sophorae Immaturus. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis. Data were also analyzed using appropriate statistical methods. Optimal extraction conditions were as follows: extraction solvent; 100% methanol; particle size; 100 mesh; extraction frequency; 1; liquid-to-solid ratio; 50:1; microwave power; 287 W; and extraction time; 80 s. A rapid and sensitive ultra-high performance liquid chromatography method coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (EIS-Q-TOF MS/MS) was developed and validated for the simultaneous determination of rutin; quercetin; genistein; kaempferol; and isorhamnetin in Flos Sophorae Immaturus. Chromatographic separation was accomplished on a Kinetex C18 column (100 mm × 2.1 mm; 2.6 μm) at 40 °C within 5 min. The mobile phase consisted of 0.1% aqueous formic acid and acetonitrile (71:29; v/v). Isocratic elution was carried out at a flow rate of 0.35 mL/min. The constituents of Flos Sophorae Immaturus were simultaneously identified by EIS-Q-TOF MS/MS in multiple reaction monitoring mode. During quantitative analysis; all of the calibration curves showed good linear relationships (R² > 0.999) within the tested ranges; and mean recoveries ranged from 96.0216% to 101.0601%. The precision determined through intra- and inter-day studies showed an RSD% of <2.833%. These results demonstrate that the developed method is accurate and effective and could be readily utilized for the comprehensive quality control of Flos Sophorae Immaturus.
To obtain the interaction characteristics between Internal solitary waves (ISWs) and submerged bodies, a three-dimensional numerical model for simulating ISWs was established in the present study ...based on the RANS equation. The velocity entrance method was adopted to generate the ISWs. First, the reliability of this numerical model was validated by comparing it with theoretical and literature results. Then, the influence of environmental and navigation parameters on interactions between ISWs and a fixed SUBOFF-submerged body was studied. According to research, the hydrodynamic performance of the submerged body has been significantly impacted by the ISWs when the body is nearing the central region of the wave. Besides, the pitching moment (
y
′) will predominate when the body encounters the ISWs at a certain angle between 0° and 180°, and the lateral force is larger than the horizontal force. Additionally, the magnitude of the force acting on the body is mostly affected by the wave amplitude. The variation of the vertical force is the main way that ISWs affect the hydrodynamic performance of the bodies. The investigations and findings discussed above can serve as a guide to forecast how ISWs will interact with submerged bodies.
In rice, an E-class gene,
OsMADS1
, acts to specify the identities of the lemma and palea. In this study, the
OsMADS1
gene with a CaMV35S promoter was transformed into a japonica cultivar, Zhonghua ...11. All transgenic plants successfully showed similar phenotypes, including dwarfism, distorted panicles, decreased numbers of branches and spikelets, and elongated sterile lemma. Histological analysis showed that the elongated sterile lemma developed with silicified epidermal and sclerenchymal cells, which were lacking in the wild-type sterile lemma, suggesting that the elongated sterile lemma had assumed the identity of the lemma or palea. Some marker genes were subjected to a detailed analysis of the distribution of their expression among the lemma, palea and sterile lemma.
DROOPING LEAF
(
DL)
and
OsMADS6
genes were only expressed in the normal lemma or palea, respectively. In the elongated sterile lemma, a high level of
DL
gene expression was detected, while no expression of
OsMADS6
was found, implying that the sterile lemma transformed into the lemma but not the palea. These results provide clues to elucidate the mechanism of evolution from lemma to sterile lemma in rice. qPCR analysis also suggested that the ectopic expression of
OsMADS1
induced abnormal brassinosteroid and gibberellin acid activation, and then resulted in developmental defects in the stem and panicle.
ABSTRACT
An early senescence leaf 4 (esl4) mutant of rice (Oryza sativa L.) displayed yellowing followed by severe chlorosis of the leaf apex and margin from the late jointing stage to maturity. The ...content of photosynthetic pigments in the mutant was significantly lower than in wild‐type plants, and abnormalities in cell structure were detected in the mutant leaf blade. Stomatal conductance and rates of photosynthesis and transpiration were lower in esl4 than in wild‐type plants. Furthermore, compared with the wild‐type, the activities of superoxide dismutase and catalase were significantly lower in esl4, whereas peroxidase activity was significantly higher in esl4. Genetic analysis indicated that the early senescence of esl4 was controlled by a recessive nuclear gene. A population of 879 F2 mutants was used to fine‐map the ESL4 gene to chromosome 4 between the insertion and deletion primers S4–42 and S4–67. This 63‐kb stretch encodes 12 uncharacterized open reading frames. Quantitative real‐time polymerase chain reaction analysis (qRT‐PCR) revealed that levels of SGR transcripts were considerably more abundant in esl4 than in wild‐type. These results provide a foundation for map‐based cloning and functional analysis of the ESL4 gene.
A 3-D time-domain seakeeping analysis tool has been newly developed by using a higher-order boundary element method with the Rankine source as the kernel function. An iterative time-marching scheme ...for updating both kinematic and dynamic free-surface boundary conditions is adopted for achieving numerical accuracy and stability. A rectangular computational domain moving with the mean speed of ship is introduced. A damping beach at the outer portion of the truncated free surface is installed for satisfying the radiation condition. After numerical convergence checked, the diffraction unsteady problem of a Wigley hull traveling with a constant forward speed in waves is studied. Extensive results including wave exciting forces, wave patterns and pressure distributions on the hull are presented to validate the efficiency and accuracy of the proposed 3-D time-domain iterative Rankine BEM approach. Computed results are compared to be in good agreement with the corresponding experimental data and other published numerical solutions.
Length of grain affects the appearance, quality, and yield of rice. A rice long-grain chromosome segment substitution line Z744, with Nipponbare as the recipient parent and Xihui 18 as the donor ...parent, was identified. Z744 contains a total of six substitution segments distributed on chromosomes (Chrs.) 1, 2, 6, 7, and 12, with an average substitution length of 2.72 Mb. The grain length, ratio of length to width, and 1 000-grain weight of Z744 were significantly higher than those in Nipponbare. The plant height, panicle number, and seed-set ratio in Z744 were significantly lower than those in Nipponbare, but they were still 78.7 cm, 13.5 per plant, and 86.49%, respectively. Furthermore, eight QTLs of different traits were identified in the secondary F2 population, constructed by Nipponbare and Z744 hybridization. The grain weight of Z744 was controlled by two synergistic QTLs (qGWT1 and qGWT7) and two subtractive QTLs (qGWT2 and qGWT6), respectively. The increase in the grain weight of Z744 was caused mainly by the increase in grain length. Two QTLs were detected, qGL1 and qGL7-3, which accounted for 25.54 and 15.58% of phenotypic variation, respectively. A Chi-square test showed that the long-grain number and the short-grain number were in accordance with the 3:1 separation ratio, which indicates that the long grain is dominant over the short-grain and Z744 was controlled mainly by the principal effect qGL1. These results offered a good basis for further fine mapping of qGL1 and further dissection of other QTLs into single-segment substitution lines.
The rice mutant ossac4 (starch accumulating 4) was raised from seeds of the rice (Oryza sativa L.) indica maintainer line Xinong 1B treated with ethyl methanesulfonate. The distal and medial portions ...of the second leaf displayed premature senescence in the ossac4 mutant at the four-leaf stage. Physiological and biochemical analysis, and cytological examination revealed that the ossac4 mutant exhibited the premature leaf senescence phenotype. At the four-leaf stage, the leaves of the ossac4 mutant exhibited significantly increased contents of starch compared with those of the wild type (WT). Quantitative real-time PCR analysis showed that the expression levels of photosynthesis-associated genes were down-regulated and the expression levels of glucose metabolism-associated genes were abnormal. Genetic analysis indicated that the ossac4 mutation was controlled by a single recessive nuclear gene. The OsSAC4 gene was localized to a 322.7-kb interval between the simple-sequence repeat marker XYH11-90 and the single-nucleotide polymorphism marker SNP5300 on chromosome 11. The target interval contained 20 annotated genes. The present results demonstrated that ossac4 represents a novel starch accumulation and premature leaf senescence mutant, and lays the foundation for cloning and functional analysis of OsSAC4.
The title compound, C
9
H
12
NO
3
F
3
S, was synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single crystal X-ray diffraction. The crystals are ...monoclinic, space group
P
2
1
/
c
,
Z
= 4, The structure is stabilized by N–H···O and C–H···F hydrogen-bonds forming a three-dimensional network.
Rice (Oryza sativa L.) is one of the most important food crops worldwide and a model monocot plant for gene function analysis, so it is an ideal system for studying flower development. This study ...reports a mutant, named multi-floret spikelet 3 (mfs3), which is related to the spikelet development in rice and derived from the ethylmethane sulfonate (EMS)-treated rice cultivar XIDA 1B. In mfs3, the main body of palea (bop) was degenerated severely and only glume-like marginal regions of palea (mrp) remained, while other floral organs developed normally, indicating that the palea identity was seriously influenced by the mutation. It was also observed that the number of floral organs was increased in some spikelets, including 2 lemmas, 4 mrp, 4 lodicules, 8–10 stamens, and 2 pistils, which meant that the spikelet determinacy was lost to some degree in mfs3. Furthermore, genetic analysis demonstrated that the mfs3 trait was controlled by a single recessive gene. Using 426 F2 mutants derived from the cross between sterile line 56S and mfs3, the MULTI-FLORET SPIKELET 3 (MFS3) gene was mapped between the molecular markers RM19347 and RM19352 on Chr.6, with a physical distance of 106.3 kb. Sequencing of candidate genes revealed that an 83-bp fragment loss and a base substitution occurred in the LOC_Os06g04540 gene in the mutant, confirming preliminarily that the LOC_Os06g04540 gene was the MFS3 candidate gene. Subsequent qPCR analysis showed that the mutation caused the down-regulation of OsMADS1 and FON1 genes, and the up-regulation of OsIDS1 and SNB genes, which are all involved in the regulation of spikelet development. The MFS3 mutation also significantly reduced the transcription of the REP gene, which is involved in palea development. These results indicated that the MFS3 gene might be involved in the spikelet meristem determinacy and palea identity by regulating the expression of these related genes.
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