Construction of a high-density genetic linkage map and identification of flowering-related QTL in erect milkvetch(Astragalus adsurgens)

Erect milkvetch(Astragalus adsurgens)is a perennial legume forage crop with economic and ecological value in livestock grazing and soil-erosion control in arid and semiarid areas worldwide.Genomic information and molecular tools to support breeding and research in the species are limited.The objectives of this investigation were to map its genome using DNA markers and to identify quantitative trait loci(QTL)in the species.An F1 mapping population of 250 plants was developed from a cross between two parents with differing flowering-related traits.A high-density genetic linkage map containing 4821 markers on eight linkage groups(LGs)with a total genetic length of 1395 cM and a mean interval of 0.29 cM between adjacent markers was constructed with SLAF-seq technology.Comparative genomic analyses revealed the highest genome sequence similarity(8.71%)between erect milkvetch and Medicago truncatula,followed by Glycine max(7.65%),Cicer arietinum(7.53%),and Lupinus angustifolius(5.21%).A total of 64 significant QTL for flowering-related traits on six LGs were detected,accounting for 9.38 to 19.1%of the associated phenotype variation.Five and 48 key candidate genes for floret number and inflorescence length were identified based on the Glycyrrhiza uralensis genome.These candidate genes were involved in ubiquitination/degradation,pollen development,cell division,cytokinin biosynthetic process,and plant flowering.These findings shed light on the regulation of flowering traits in erect milkvetch and provide genomic resources for future molecular breeding of the crop.

Meta-Analysis of Flowering-Related Traits and Mining of Candidate Genes in Maize

Maize flowering is an important agronomic character,which is controlled by quantitative trait loci(QTL).Over the years,a large number of flowering-related QTL have been found in maize and exist in public databases.However,combining these data,re-analyzing and mining candidate loci and fine mapping of flowering-related traits to reduce confidence intervals has become a hot issue in maize.In this study,the QTL of 6 important agronomic traits of maize flowering were collected from 15 published articles,including flowering period(DA),Days to tasseling(DTT),Days to silking(DS),Days to pollen shedding(DTP),anthesis-silking interval(ASI)and the photosensitive(PS).Through meta-analysis,622 QTL were integrated into 26 meta-QTLs(MQTL).Finally,the candidate genes related to maize flowering(Gene IDs:ZM00001D005791,ZM00001D019045,ZM00001D050697,ZM00001D011139)were identified by Gene Ontology(GO)enrichment and hierarchical cluster analysis of expression profile.Based on the results of this study,the genetic characteristics of maize flowering traits will be further analyzed,which is of great significance to guide the improvement of important agronomic characters and improve the efficiency of breeding.

FLOWERING LOCUS T(FT)in Photosensitive Type Chrysanthemum Accelerates Flowering in Arabidopsis

FLOWERING LOCUS T(FT)is an important factor for integrating flowering signals through the photoperiod pathway,which significantly promotes flowering.Most chrysanthemum varieties are short-day plants,sensitive to the photoperiod,which limits their ornamental and annual production supply.In this study,we aim to analyze the nutrients and flowering-related genes of chrysanthemums with different photoperiod types and to clone and verify the function of the flowering-related gene CmFT.We found that the formation of floral buds requires the accumulation of starch while consuming soluble sugars and the expression patterns of flowering-related genes GIGANTEA(GI),CONSTANS(CO),and FT in C.morifolium‘Zilian’and C.morifolium‘Zihongtuogui’had a certain synchronization during floral buds differentiation according to our quantitative validation,and the expression levels of CmGI,CmCO and CmFT in C.morifolium‘Zihongtuogui’were higher than those in C.morifolium.‘Zilian’in the later stage of differentiation.CmFT was cloned from photosensitive chrysanthemums-C.morifolium‘Zihongtuogui’and polypeptide alignment and phylogenetic analysis showed that CmFT was clustered in FT-like subfamily.In further functional verification,we obtained two Arabidopsis transgenic lines.Our results showed that CmFT transgenic ft mutant lines can significantly accelerate flowering in Arabidopsis.Thus,we can initially confirm that CmFT plays an important role in promoting flowering,which may be the key reason for the photosensitivity of C.morifolium‘Zihongtuogui’.Overall,the results of this study are of great importance in revealing the flowering mechanism of different photoperiod types of chrysanthemums.