Core clock component MtLUX controls shoot architecture through repression of MtTB1/MtTCP1A in Medicago truncatula

Plants are capable of regulating their shoot architecture in response to diverse internal and external environments.The circadian clock is an adaptive mechanism that integrates information from internal and ambient conditions to help plants cope with recurring environmental fluctuations.Despite the current understanding of plant circadian clock and genetic framework underlying plant shoot architecture,the intricate connection between these two adaptive mechanisms remains largely unclear.In this study,we elucidated how the core clock gene LUX ARRHYTHMO(LUX)regulates shoot architecture in the model legume plant Medicago truncatula.We show that mtlux mutant displays increased main stem height,reduced lateral shoot length,and decreased the number of lateral branches and biomass yield.Gene expression analysis revealed that Mt LUX regulated shoot architecture by repressing the expression of strigolactone receptor MtD14 and MtTB1/MtTCP1A,a TCP gene that functions centrally in modulating shoot architecture.In vivo and in vitro experiments showed that Mt LUX directly binds to a cis-element in the promoter of MtTB1/MtTCP1A,suggesting that Mt LUX regulates branching by rhythmically suppressing MtTB1/MtTCP1A.This work demonstrates the regulatory effect of the circadian clock on shoot architecture,offering a new understanding underlying the genetic basis towards the flexibility of plant shoot architecture.

A single nucleotide substitution in the MATE transporter gene regulates plastochron and the many noded dwarf phenotype in barley(Hordeum vulgare L.)

In higher plants,the shoot apical meristem produces lateral organs in a regular spacing(phyllotaxy)and timing(plastochron).The molecular analysis of mutants associated with phyllotaxy and plastochron would increase our understanding of the mechanism of shoot architecture formation.In this study,we identified mutant mnd8ynp5 that shows an increased rate of leaf emergence and a larger number of nodes in combination with a dwarfed growth habit from an EMS-treated population of the elite barley cultivar Yangnongpi 5.Using a map-based cloning strategy,the mnd8 gene was narrowed down to a 6.7-kb genomic interval on the long arm of chromosome 5H.Sequence analysis revealed that a C to T single-nucleotide mutation occurred at the first exon(position 953)of HORVU5Hr1G118820,leading to an alanine(Ala)to valine(Val)substitution at the 318th amino acid site.Next,HORVU5Hr1G118820 was defined as the candidate gene of MND8 encoding 514 amino acids and containing two multidrug and toxic compound extrusion(MATE)domains.It is highly homologous to maize Bige1and has a conserved function in the regulation of plant development by controlling the leaf initiation rate.Examination of modern barely varieties showed that Hap-1 was the dominant haplotype and was selected in barley breeding around the world.Collectively,our results indicated that mnd8ynp5 is a novel allele of the HORVU5Hr1G118820 gene that is possibly responsible for the shortened plastochron and many noded dwarf phenotype in barley.

Analyzing architectural diversity in maize plants using the skeletonimage-based method

Shoot architecture in maize is critical since it determines resource use,impacts wind and rain damage tolerance,and affects yield stability.Quantifying the diversity among inbred lines in heterosis breeding is essential,especially when describing germplasm resources.However,traditional geometric description methods oversimplify shoot architecture and ignore the plant’s overall architecture,making it difficult to reflect and illustrate diversity.This study presents a new method to describe maize shoot architecture and quantifies its diversity by combining computer vision algorithms and persistent homology.Our results reveal that persistent homology can capture key characteristics of shoot architecture in maize and other details often overlooked by traditional geometric analysis.Based on this method,the morphological diversity of shoot architecture can be mined(quantified),and the main shoot architecture types can be obtained.Consequently,this method can easily describe the diversity of shoot architecture in many maize materials.

Genetic analysis and gene mapping of a dwarf and liguleless mutation in barley

Leaf development underlies crop growth and productivity and has been a major target of crop domestication and improvement.However,most genes controlling leaf development in barley remain unknown.We identified a dwarf and liguleless(dl)mutant derived by ethylmethane sulfonate mutagenesis.The dl mutant showed dramatic changes in shoot architecture compared with wild-type(Yangnongpi 5)plants.Besides lacking ligules,the dl mutant showed much shorter plant height(28 cm)than Yangnongpi 5(78 cm).By map-based cloning,the dl gene was localized to a 56.58-kb genomic interval on the long arm of chromosome 7.A C-to-T single-nucleotide substitution was identified at exon position 790,and is a functional mutation resulting in a proline-to-serine substitution at the 264th amino acid residue of HORVU7Hr1G106960.Consequently,HORVU7Hr1G106960 was identified as the DL gene,encoding 269 amino acids and containing the Arabidopsis LSH1 and Oryza G1(ALOG)domain.DL is highly similar to rice OsG1-LIKE 1/2(OsG1L1/2)and sorghum AWN1/AWN1-10 at the amino acid level.Although the dl mutant allele showed no expression changes in selected tissues by real-time PCR,we propose HORVU7Hr1G106960 as a candidate gene conferring the dwarf and liguleless phenotype in barley.