Production Of T2DS-2AS.2AL Translocation Harboring Of Photoperiod Gene Ppd-D1a

Heading date is a key agronomic trait that determines the regional adaptability and yield of crop plants.In common wheat,photoperiod-1 {Ppd1)loci on short arm of 2 homoeologous group chromosomes are the key regulators of heading time thought senses the day length.Wheat requires a certain day-length to promote heading and flowering,but photoperiod-insensitive alleles at Ppd-1 loci can induce heading irrespective of day length.Molecular biology analysis shows that the expression level of Ppd1 genes is crucial for this controlling system.Among different homoeo-alleles,Ppd-D1 on 2DS has the largest influence.The Ppd-D1a allele is no longer sensitive to photoperiod due to sequence variations in the promoter and the first intron regions,which leads to an high expression level.Therefore,increasing the expression level of Ppd-D1 gene may significantly promote wheat heading and flowering early.Based on this,the study plans to use the ph1b gene to induce recombination of wheat 2A and 2D chromosomes,replacing the corresponding homologous segment of 2AS with a small 2DS fragment carrying Ppd-D1a,thus laying the foundation for creating new materials carrying multiple copies of Ppd-D1a.The main results is as follows:(1)Cytological analysis revealed that the homoeologous recombination frequency of 2A-2D induced by ph1b was relatively high,with a short arm recombination frequency of 8.7%and a long arm recombination frequency of 32.6%;By screening a population with 138 plants,11 types of 2A-2D homoeologous recombinants were obtained.Among them,the translocation chromosomes in 2S2B300-21,2S2B301-19,and 2S2B301-33 may carry the Ppd-D1a gene.(2)Using specific molecular markers,it was demonstrated that the 2DS-2AS.2AL-2SL translocation chromosome in plant 2S2B301-33 harbors the Ppd-D1a gene.This translocation chromosome is discovered in offspring through plant selfing,laying the foundation to create special new materials carrying multiple copies of Ppd-D1a in further.(3)In addition to the target translocation type,15 translocation chromosomes formed by the recombination of 2S(from Aegilops variabilis)and wheat homologous group 2 chromosomes were also obtained;Except for 2 homologous group chromosomes,the homoeologous recombinants involving other five homoeologous group chromosomes(except homologous group 4 chromosomes)were also obtained.The recombination frequency of A-D homoeologous chromosomes is significantly higher than that of B-D and A-B homoeologous chromosomes.A 2B/2D double monosomic with high seed setting rate was identified,laying the foundation for creating 2B-2D translocation carrying Ppd-D1a in further.