Effect Of The High Molecular Weight Glutenin Subunit Bx7-m566GR And By9-m292GE369QR On Wheat Processing Quality

The composition and content of wheat seed storage protein determined the processing quality of wheat.which mainly include gliadin and glutenin.And the glutenin can be divided into high molecular weight glutenin subunit?HMW-GS?and low molecular weight glutenin subunit?LMW-GS?according to the differential mobility.The HMW-GS was the key protein which determined the processing quality of wheat,although it only accounted for 10%of wheat grain protein,but it was still regarded as the"skeleton"of gluten network,and it can significantly affect the rheological properties of dough.In this experimental material,Shumai482 was mutagenized with ethyl methane sulfonate?EMS?,and the superior individual plant was selected.Then the slower mobility of Bx7 and By9 subunit was screened by SDS-PAGE which marked the Bx7-m566GR and By9-m292GE369QR subunit.And the mutant was backcrossed with Shumai482?contrast?to construct BC₁F₄ segregating population for measuring its quality parameters.In this paper,gene cloning?sequence determination and secondary structure prediction of Bx7-m566GR and By9-m292GE369QR subunit were carried out,and the effect of Bx7-m566GR and By9-m292GE369QR subunit on wheat processing quality was preliminarily discussed.The results are as follows:1.Agronomic traitsThere was no significant difference in panicle length,tiller number and spikelet number between mutant type Bx7-m566GR and wild type Bx7 plants,but the plant height of the former was higher than that of the latter;the seed traits of the two populations were more consistent;There was also no significant difference in plant height,ear length and spikelet number between the mutant type By9-m292GE 369QR and wild type plants,and the grain traits of the two was also no significant difference;however,the former had fewer tillers than the latter.2.SDS-PAGE screening materialsThe SDS-PAGE was used to check the mutant type Bx7-m566GR and By9-m292GE369QR with slower mobility than the wild type of Bx7 and By9 subunit.Then 4M urea?protein denaturant?was added to the separation gel,the result showed that the mutant type and wild type presented identical mobility.3.The gene cloning and sequence comparison of HMW-GSMaking use of the high conservation of the N-terminal and C-terminal sequences of the HMW-GS gene,specific primers were designed to amplify the coding region sequences of the Bx7 and By9 subunits.The result showed that the gene sequence of Bx7 subunit was 2370 bp,encoding 788 amino acids in total,while the full length of the By9 subunit gene sequence was 2118 bp,encoding a total of 704 amino acids.The sequence analysis revealed that the wild type Bx7 and By9 subunits were consistent with the reported gene sequences.However the 1696th nucleotide G of the Bx7-m566GR gene sequence was replaced with the single nucleotide A;caused a change in position 566th amino acid of protein sequence,caused the replacement of glycine by arginine;mean that,altering its protein sequence.Whereas the 878th mononucleotide G of the By9-m292GE369QR gene sequence was replaced by A and its?1106th mononucleotide A was replaced with G,caused the protein sequence of292nd glycine?G?mutated theglutamine?E?,which was encoded by the codon GAG and CAA respectively.And Its?369th glutamine?Gln,Q?was substituted with arginine?Arg,R?,which leads to a change in its amino acid sequence.4,The secondary structure analysisTaking advantage of the Antheprot6.6.1 software predicted the secondary structure of the protein sequence of the wild type of Bx7 and By9 and mutant type of Bx7-m566GR and By9-m292GE369QR.It was found that the single amino acid change of t Bx7-m566GR subunit not cause its spatial structure change;while the two amino acid positions of the mutant By9-m292GE369QR subunit changed,resulting in the?-turn structure change near the 292th amino acid and the 369th the?-turn and ?-sheet near the amino acid change;eventually,the spatial structure of the amino acid sequence changes,that is,the?-helix increases,and the random curl decreases.5.The processing quality parameters analysisAnalysis of the measured processing quality parameters showed that there was no significant difference in the quality parameters between the mutant type of Bx7-m566GR and By9-m292GE369QR and its wild type of Bx7 and By9,but the content of the granule protein,the content of the wet gluten,its sedimentation value,the formation time,the stability time and rupture time of the mutant type of Bx7-m566GR increased to different extents compared with wild type Bx7;while the mutant type of By9-m292GE369QR showed an opposite trend;indicating that the slower mobility of the Bx7 and By9 subunit may have a certain improvement effect on its processing quality.