Enhancer of Shoot Regeneration 2(ESR2)regulates pollen maturation and vitality in watermelon(Citrullus lanatus)

Watermelon(Citrullus lanatus)holds global significance as a fruit with high economic and nutritional value.Exploring the regulatory network of watermelon male reproductive development is crucial for developing male sterile materials and facilitating cross-breeding.Despite its importance,there is a lack of research on the regulation mechanism of male reproductive development in watermelon.In this study,we identified that ClESR2,a VIIIb subclass member in the APETALA2/Ethylene Responsive Factor(AP2/ERF)superfamily,was a key factor in pollen development.RNA insitu hybridization confirmed significantClESR2 expression in the tapetum and pollen during the later stage of anther development.The pollens of transgenic plants showed major defects in morphology and vitality at the late development stage.The RNA-seq and protein interaction assay confirmed that ClESR2 regulates pollen morphology and fertility by interacting with key genes involved in pollen development at both transcriptional and protein levels.These suggest that Enhancer of Shoot Regeneration 2(ESR2)plays an important role in pollen maturation and vitality.This study helps understand the male reproductive development of watermelon,providing a theoretical foundation for developing male sterile materials.

WUSCHEL-related homeobox1(WOX1)regulates vein patterning and leaf size in Cucumis sativus

In plants,WUSCHEL-related homeobox1(WOX1)homologs promote lamina mediolateral outgrowth.However,the downstream components linking WOX1 and lamina development remain unclear.In this study,we revealed the roles of WOX1 in palmate leaf expansion in cucumber(Cucumis sativus).A cucumber mango fruit(mf)mutant,resulting from truncation of a WOX1-type protein(CsWOX1),displayed abnormal lamina growth and defects in the development of secondary and smaller veins.CsWOX1 was expressed in the middle mesophyll and leaf margins and rescued defects of the Arabidopsis wox1 prs double mutant.Transcriptomic analysis revealed that genes involved in auxin polar transport and auxin response were highly associated with leaf development.Analysis of the cucumber mf rl(round leaf)double mutant revealed that CsWOX1 functioned in vein development via PINOID(CsPID1)-controlled auxin transport.Overexpression of CsWOX1 in cucumber(CsWOX1-OE)affected vein patterning and produced‘butterfly-shaped’leaves.CsWOX1 physically interacted with CsTCP4a,which may account for the abnormal lamina development in the mf mutant line and the smaller leaves in the CsWOX1-OE plants.Our findings demonstrated that CsWOX1 regulates cucumber leaf vein development by modulating auxin polar transport;moreover,CsWOX1 regulates leaf size by controlling CIN-TCP genes.

Development of branchless watermelon near isogenic lines by marker assisted selection

Pruning is time-consuming and laborious in watermelon cultivation,which can not meet the needs for simplified cultivation in the future.The development of branchless lines will provide important germplasms for breeding watermelon varieties and is an important method for genetic improvement.In this study,the watermelon accession,Wu Cha Zao(WCZ)is a branchless inbred line that carries the branchless gene Clbl,which was used as the donor parent to develop branchless near isogenic lines(NILs).To construct the NILs of Clbl,WCZ crossed with the normal branching watermelon inbred line WT20 which was used as the recurrent parent.The co-segregating markers dCAPS10 and Indel1 with Clbl were used for foreground selection,and a total of 108 SSR markers was selected with good polymorphism between two parental lines for background selection which had relatively uniform distribution across 11 chromosomes.Using these markers to select individuals from the BC_(1)F_(1),BC_(2)F_(1),and BC_(2)F_(2) generations,three NILs with a proportion of recurrent parent genome(PRPG)>99%were finally obtained.The lateral branch and plant height phenotypes did not significantly differ between the NILs and WCZ,indicating that the NILs of Clbl under the genetic background of WT20 has been successfully developed.These results provide ideal materials for further in-depth analysis of the genetic mechanisms of lateral branch development and ideal plant architecture breeding in watermelon.

HD-Zip Transcription Factor is Responsible for No-Lobed Leaf in Watermelon(Citrullus lanatus L.)

Leaf is a vital organ of plants that plays an essential role in photosynthesis and respiration.As an important agronomic trait in leaf development,leaf shape is classified into lobed,entire(no-lobed),and serrated in most crops.In this study,two-lobed leaf watermelon inbred lines WT2 and WCZ,and a no-lobed leaf watermelon inbred line WT20 were used to create two F_(2)populations.Segregation analysis suggested that lobed leaves were dominant over the no-lobed leaves,and it was controlled by a signal gene.A locus on watermelon chromosome 4 controlling watermelon lobed/no-lobed leaves was identified through BSA-seq strategy combined with linkage analysis.The candidate gene was fine-mapped to a 61.5 kb region between 21,224,481 and 21,285,957 bp on watermelon chromosome 4 using two F_(2)populations.Four functional genes were annotated in the candidate region,while sequences blast showed that there was a single-base deletion(A/-)only in the exon of Cla018360,which resulted in premature termination of translation in the no-lobed leaf lines.Function prediction showed that Cla018360 encodes an HD-Zip protein that has been reported to regulate the development of leaf shape.The single-base deletion also occurred in the HD-Zip domain.We inferred that the Cla018360 gene is the candidate gene for regulating the development of lobed/no-lobed leaves in watermelon.Gene expression analysis showed that Cla018360 was highly expressed in young leaves.Phylogenetic analysis showed that Cla018360 had a close genetic relationship with AtHB51,which had been reported to regulate the formation of leaf shape in Arabidopsis.Furthermore,transcriptome analysis showed that a total of 333 differentially expressed genes were identified between WT2 and WT20,of which 115 and 218 genes were upregulated and downregulated in no-lobed leaved watermelon WT20.This study not only provides a good entry point for studying leaf development but also provides foundational insights into breeding for special plant architecture in watermelon.

Gynoecy instability in cucumber(Cucumis sativus L.)is due to unequal crossover at the copy number variation-dependent Femaleness(F)locus

Cucumber,Cucumis sativus is an important vegetable crop,and gynoecy has played a critical role in yield increase of hybrid cucumber production.Cucumber has a unique genetic system for gynoecious sex expression,which is determined by the copy number variation(CNV)-based,dominant,and dosage-dependent femaleness(F)locus.However,this gynoecy expression system seems unstable since monecious plants could often be found in Fdependent gynoecious cucumber inbreds.We hypothesized that gynoecy instability(gynoecy loss)may be due to unequal crossing over(UCO)during meiosis among repeat units of the CNV.In this study,using high throughput genome resequencing,fiber-FISH and genomic qPCR analyses,we first confirmed and refined the structure of the F locus,which was a CNV of a 30.2-kb tandem repeat.Gynoecious plants contained three genes:CsACS1,CsACS1G,and CsMYB,of which CsACS1G is a duplication of CsACS1 but with a recombinant distal promoter that may contribute to gynoecy sex expression.In two large populations from self-pollinated gynoecious inbred lines,‘gynoecy loss’mutants were identified with similar mutation rates(~0.12%).We show that these monecious mutants have lost CsACS1G.In addition,we identified gynoecious lines in natural populations that carry two copies of CSACS1G.We proposed a model to explain gynoecy instability in F-dependent cucumbers,which is caused by UCO among CSACS1/G units during meiosis.The findings present a convincing case that the phenotypic variation of an economically important trait is associated with the dynamic changes of copy numbers at the F locus.This work also has important implications in cucumber breeding.

Enhanced electromagnetic wave absorption via optical fiber-like PMMA@Ti_(3)C_(2)T_(x)@SiO_(2) composites with improved impedance matching

Ti_(3)C_(2)T_(x) nanosheets have attracted significant attention for their potential in electromagnetic wave absorption(EWA).However,their inherent self-stacking and exorbitant electrical conductivity inevitably lead to serious impedance mismatch,restricting their EWA application.Therefore,the optimization of impedance matching becomes crucial.In this work,we developed polymethyl methacrylate(PMMA)@Ti_(3)C_(2)T_(x)@SiO_(2) composites with a sandwich-like core–shell structure by coating SiO_(2) on PMMA@Ti_(3)C_(2)T_(x).The results demonstrate that the superiority of the SiO_(2) layer in combination with PMMA@Ti_(3)C_(2)T_(x),outperforming other relative graded distribution structures and meeting the requirements of EWA equipment.The resulting PMMA@Ti_(3)C_(2)T_(x)@SiO_(2) composites achieved a minimum reflection loss of-58.08 dB with a thickness of 1.9 mm,and an effective absorption bandwidth of 2.88 GHz.Mechanism analysis revealed that the structural design of SiO_(2) layer not only optimized impedance matching,but also synergistically enhanced multiple loss mechanisms such as interfacial polarization and dipolar polarization.Therefore,this work provides valuable insights for the future preparation of high-performance electromagnetic wave absorbing Ti_(3)C_(2)T_(x)-based composites.

Construction of hydrangea-like core-shell SiO_(2)@Ti_(3)C_(2)T_(x)@CoNi microspheres for tunable electromagnetic wave absorbers

Ti_(3)C_(2)T_(x)MXene shows great potential in the application as microwave absorbers due to its high attenuation ability.However,excessively high permittivity and self-stacking are the main obstacles that constrain its wide range of applications.To tackle these problems,herein,the microspheres of SiO_(2)@Ti_(3)C_(2)T_(x)@CoNi with the hydrangea-like core-shell structure were designed and prepared by a combinatorial electrostatic assembly and hydrothermal reaction method.These microspheres are constructed by an outside layer of CoNi nanosheets and intermediate Ti_(3)C_(2)T_(x)MXene nanosheets wrapping on the core of modified SiO_(2),engendering both homogenous and heterogeneous interfaces.Such trilayer SiO_(2)@Ti_(3)C_(2)T_(x)@CoNi microspheres are“magnetic microsize supercapacitors”that can not only induce dielectric loss and magnetic loss but also provide multilayer interfaces to enhance the interfacial polarization.The optimized impedance matching and core-shell structure could boost the reflection loss(RL)by electromagnetic synergy.The synthesized SiO_(2)@Ti_(3)C_(2)T_(x)@CoNi microspheres demonstrate outstanding microwave absorption(MA)performance benefited from these advantages.The obtained RL value was-63.95 dB at an ultra-thin thickness of 1.2 mm,corresponding to an effective absorption bandwidth(EAB)of 4.56 GHz.This work demonstrates that the trilayer core-shell structure designing strategy is highly efficient for tuning the MA performance of MXene-based microspheres.