Study On Endosperm Development, Morphological Features Of Starch Granules And Sencondry Structure Of Glutens In HMW Near-isogenic Lines Of Wheat

Endosperm texture is one of the most important quality characteristics of wheat and itlargely determines the end-use quality of wheat cultivar. Starches and proteins are the majorconstituent of the wheat endosperm. Moreover, the morphological features of starch granulesand sencondry structure of proteins effect the functional properties of wheat. In this study,waxy wheat Shannuo1and HMW-GS near-isogenic lines of Xinong1330were used toanalyze the effects of different HMW-GS compositions on the texture of endosperm,morphological features of starch granules and sencondry structure of glutens, and also studythe difference between waxy wheat Shannuo1and non-waxy wheat Xinong1330about theendosperm development and morphological features of starch granules by scanning electronmicroscope(SEM), MASTERSIZER-2000laser particle and FT-Raman spectroscopy. Theresults of the research are as follows:(1) It was shown that the texture of endosperm obviously differ among HMW-GSnear-isogenic lines of Xinong1330.AtGlu-A1locus, there were minor differences in thetexture of endosperm between N and1; atGlu-B1locus,14+15and17+18exhibited a denselayer of protein matrix, which enveloped and masked starch grains;at Glu-D1locus,comparedwith2+12, the endosperm of5+10contained more protein matrix and the combinationbetween protein and starch granules was much tighter.(2)Under SEM there were no detectable differences in the granule morphology, but thesize distribution of starch granules was different between HMW-GS near-isogenic lines ofXinong1330.At Glu-A1locus,the percentage of the volume, the surface area and the numberof B type starch granules in N were all higher than those in1; at Glu-B1locus, the sizedistribution of B type starch granules showed a significant discrepancy, the order of the volumeand surface area percentageswas14+15>17+18>7+8>7+9, the order of the numberpercentages was7+8>14+15>17+18>7+9; at Glu-D1locus, the percentage of the volume, thesurface area and the number of B type starch granules in5+10were all higher than those in2+12.(3) The secondary structures of glutens among HMW-GS near-isogenic lines ofXinong1330were changed. At Glu-A1locus, N showed a lower proportion of a-helixconformation and a higher proportion of β-sheet content than1; at Glu-B1locus, the order ofa-helix contents was7+8>7+9>17+18>14+15, the proportions of β-sheet conformationwere Just the opposite; at Glu-D1locus, the content of a-helix in5+10was obviously lowerthan those in2+12, while the proportion of β-sheet conformation was higher inversely. Forthe hydrophobicity of the glutens, N>1;14+15>17+18>7+8>7+9;5+10>2+12.(4) The endosperm cells of waxy wheat Shannuo1were smaller and developed slowerthan those of non-waxy wheat Xinong1330during grain development. In the early period ofthe endosperm development, the starch granules of Shannuo1and Xinong1330can bestained well by toluidine. In the late period of the grain development, the starch granules ofShannuo1can also be stained well, but Xinong1330can not. Compared with Xinong1330,the endosperm of Shannuo1contained less protein matrix and the combination betweenprotein and starch granules was much looser. The shape of B type starch granules of Shannuo1was irregular polygon, while that of Xinong1330was spherical. The size distribution ofstarch granules varied between waxy and non-waxy wheat. Volume distribution of Shannuo1starch granules showed a typical four-peak distribution with peak values of0.4to1μm，1to10μm，10to53μm and more than53μm，while that of Xinong1330showed bimodaldistribution. Granule surface area distribution of both cultivars indicated a typical three-peakdistribution with peak values of0.4to1μm，1to10μm，10to53μm，respectively．Numberdistribution of granules in waxy and non-waxy starch was a typical population with a peakvalue in the range of0.4to1μm．The percentage of starch granules of Shannuo1and Xinong1330were nearly identical. In contrast, the percentage of the volume and the surface area ofShannuo1differed significantly from those of Xinong1330. For A type starch granules, thepercentage of the volume and the surface area of Shannuo1were both lower than those ofXinong1330. While for B type starch granules, those of Shannuo1were higher than those ofXinong1330. The volume, surface area and number of SB type starch granules of Shannuo1 were lower than those of Xinong1330by1.11%,11.60%and9.28%, respectively, whereasthe LB type starch granules of Shannuo1were higher than those of Xinong1330by8.27%,15.88%and9.27%, respectively. A minority LA type starch granules was found in Shannuo1,but not in Xinong1330.