Abstract: 【Objective】 The aim of this research is to study the endosperm development and morphological features of starch in waxy wheat Shannuo 1 and non-waxy wheat Xinong 1330, which will provide a theoretical basis for quality improvement of wheat breeding. 【Method】 Two wheat cultivars, Shannuo 1 (waxy wheat) and Xinong 1330 (non-waxy wheat) were used as materials in this paper. The development of endosperm cells were observed by optical microscope. In order to preserve the endosperm structure, the developing grains (5, 8, 12, 15, 18, 21, 25 and 28 d after fertilization) were immersed in glutaraldehyde and osmic acid after transected by freezing in liquid nitrogen. Before embedded with Epon812, samples were washed with phosphate buffer and dehydrated individually in a graded acetone solution. The semi-thin slices were obtained by Leica ULTRACUT slicer. Images were taken by optical microscope after stained by 1% toluidine. The cross sections of Shannuo 1 and Xinong 1330 grains and starch samples which isolated from the two wheat varieties were placed on an aluminum specimen holder, and sputter-coated with a thin ?lm of gold under vacuum condition. Samples were observed with a JEOL scanning electron microscope (JSM-6360LV, JEOL, Japan). Particle size distribution of the starch samples was measured by MASTERSIZER-2000 laser particle analyzer (Malvern UK company). All measurements were performed in triplicates. Analysis of variance (ANOVA) was performed using LSD’s test to compare treatment variations at a signi?cance level of P＜0.05 with DPS software. The data figures were performed by Sigmaplot 12.0 software. 【Result】 The results indicated that the endosperm cells of waxy wheat Shannuo 1 were smaller and developed slower than those of non-waxy wheat Xinong 1330 during grain development. In the early period of the endosperm development, the starch granules of Shannuo 1 and Xinong 1330 could be stained well by toluidine. However, in the late period of the grain development, the starch granules of Shannuo 1 could also be stained well, but Xinong 1330 can not. Compared with Xinong 1330, the endosperm of Shannuo 1 contained less protein matrix and the combination between protein and starch granules was much looser. The shape of B type starch granules of Shannuo 1 was irregular polygon, while that of Xinong 1330 was spherical. There was no significant difference in the shape of A type starch granules between Shannuo 1 and Xinong 1330. The size distribution of starch granules varied between waxy and non-waxy wheat. Volume distribution of Shannuo 1 starch granules showed a typical four-peak distribution, while that of Xinong 1330 showed a bimodal distribution. Granule surface area distribution of both cultivars indicated a typical three-peak distribution. The number distribution of granules in waxy and non-waxy starch was a typical unimodal distribution．The percentage of starch granules of Shannuo 1 and Xinong 1330 was nearly identical. In contrast, the percentage of the volume and the surface area of Shannuo 1 differed significantly from those of Xinong 1330. For A (>10 μm) type starch granules, the percentage of the volume and the surface area of Shannuo 1 were both lower than those of Xinong 1330. While for B (<10 μm) type starch granules, those of Shannuo 1 were higher than those of Xinong 1330. The volume, surface area and number of SB (<1 μm) type starch granules of Shannuo 1 were lower than those of Xinong 1330 by 1.11%, 11.60% and 9.28%, respectively, whereas the LB (1-10 μm) type starch granules of Shannuo 1 were higher than those of Xinong 1330 by 8.27%, 15.88% and 9.27%, respectively. A minority LA (>53 μm) type starch granules was found in Shannuo 1, but not in Xinong 1330. 【Conclusion】 In conclusion, the development of endosperm and the morphological features of starch granules of waxy wheat Shannuo 1 were significantly different from those of non-waxy wheat Xinong 1330 during grain development. The starch granules of LB type had considerable effects on the B type starch granules size distribution of Shannuo 1 and Xinong 1330.

Key words: waxy wheat, endosperm, starch, particle size, microstructure