Development Of A Hexaploid Wheat Line With HMW-GS Dy12

The HMW-GSs among wheat cultivars varied from3to5, of which, the two subunits encode by the Glu-D1are usually expressed. A question is that how HMW-GS affects wheat quality when the expression genes of HMW-GS reduced to three or below three? However, this question could not be addressed because no such wheat lines. For this purpose, a new wheat line, only express a Dy12subunit, is acquired from the crosses between a synthetic wheat line containing double null alleles at Glu-A1and Glu-B1and express two HMW-GS from D genome of Aegilops tauschii and a Dx silenced Sichuan landrace wheat WL16with HMW-GS combinations of7+8and12. The HMW-GS compositions in F2and F3were confirmed and separated by SDS-PAGE. Also, the chromosome numbers in the root tip cells and the chromosome pairing configuration in the PMC at meiotic metaphase I were analyzed. Further, to elucidate the molecular mechanism underlying the silence of IDx in WL16, the coding and5’upstream sequences were determined. The main results are as follows:1. Fifty-seven seeds, expression HMW-GS Dy12, were detected by SDS-PAGE from a randomly sampled F2with1000grains. The chromosome numbers of33plants were counted,29of which had42,4of them varied from39to41.2. The HMW-GSs of1000seeds belonging to42F3families were detected, of which,39F3families had Dy12and3F3families had no HMW-GS. Chromosome counting of36family lines indicated that28F3families had42, and8F3families ranged from39to41. The chromosome pairing configuration in the PMC at meiotic metaphase I for42F3families were different from each other. Distinctively, P715had more univalent and rod bivalents, with a mean of15.66and7.81, respectively, than the other family lines. P715 produced fewest grains among all F3family lines, probably caused by the high frequency of univalent. In addition, the lagging chromosomes in the equatorial plate at meiosis metaphase I were detected in some F3family lines.3. No HMW-GS was detected in seven seeds from some F3family lines. Four of the seven seeds were germinated and planted in the field. The chromosome numbers for three of the four plants were ranged from39to41. It was suggested that absence of the one to three chromosomes including at least one1D were respectively responsible for no HMW-GS was detected in the seeds with39,40and41chromosomes in root chips.4. The coding and the5’upstream sequences of IDx silence gene in Sichuan wheat landrace WL16were isolated and sequenced. Sequence alignment indicated that silence of IDx in WL16was mainly caused by the single base replacement involved in C to T leaded to the triplet code CAG for glutamine (G) changed to stop codon TAG located at1453bp positions in the coding sequence.