In the developing wheat grain, nutrients from the spikelet axis are delivered to the endosperm via the nutrient transfer tissues (NTTs). Knowledge of the NTTs development is paramount to understanding the accumulation of starch and protein in wheat grain. In this study, two near-isogenic lines including ‘Shimai19-P’ and ‘Shimai19-N’ and a wheat cultivar ‘Shimai19’ were used to analyze the anatomical structure of the large vascular bundle, chalaza, nucellar projection, and the small vascular bundle in wheat grains at 0–20 days after pollination (DAP) using paraffin sectioning and semi-thin sectioning techniques. The phloem sieve tubes reached the maximal number at 4 DAP in ‘Shimai19-P’ and ‘Shimai19’; however, phloem sieve tubes of ‘Shimai19-N’ reached the maximum number at 6 DAP. The transverse section areas of the small vascular bundles of ‘Shimai19-N’ and ‘Shimai19-P’ reached the highest value at 8 DAP, while the sieve tubes and parenchyma cells in the small vascular vessels decreased significantly. At 12 DAP, nuclei of the chalazal cells in the three wheat varieties began gradually disappearing, with the most apparent changes reported in ‘Shimai19-N’. In conclusion, there was significant variation in the formation of sieve tubes and vessels in large vascular bundles, the disappearance of chalazal cell nuclei, and the transverse section area of small vascular bundles in different waxy wheat grains, which is considered as the important morphological and anatomical basis for the difference of wheat starch and nutrients accumulation.

在发育中的小麦籽粒中，来自小穗轴的养分通过养分转移组织 (NTT) 传递到胚乳。了解 NTTs 的发展对于了解小麦籽粒中淀粉和蛋白质的积累至关重要。本研究采用'Shimai19-P'和'Shimai19-N'两个近等基因系和小麦品种'Shimai19'对大维管束、合点、珠心投影和小维管束的解剖结构进行分析。使用石蜡切片和半薄切片技术在授粉后 0-20 天（DAP）将小麦籽粒捆扎起来。'世麦19-P'和'世麦19'的韧皮部筛管在4 DAP时达到最大值；而'Shimai19-N'的韧皮部筛管在6 DAP时达到最大数量。'Shimai19-N'和'Shimai19-P'小维管束横切面面积在8 DAP时达到最高值，而小血管内筛管和薄壁细胞明显减少。在12 DAP，三个小麦品种的合点细胞核开始逐渐消失，其中'Shimai19-N'报道的变化最为明显。综上所述，不同糯小麦籽粒大维管束的筛管和血管形成、合点细胞核的消失、小维管束的横截面积存在显着差异，被认为是重要的形态学特征。小麦淀粉和养分积累差异的解剖学基础. 而小血管内的筛管和薄壁细胞明显减少。在12 DAP，三个小麦品种的合点细胞核开始逐渐消失，其中'Shimai19-N'报道的变化最为明显。综上所述，不同糯小麦籽粒大维管束的筛管和血管形成、合点细胞核的消失、小维管束的横截面积存在显着差异，被认为是重要的形态学特征。小麦淀粉和养分积累差异的解剖学基础. 而小血管内的筛管和薄壁细胞明显减少。在12 DAP，三个小麦品种的合点细胞核开始逐渐消失，其中'Shimai19-N'报道的变化最为明显。综上所述，不同糯小麦籽粒大维管束的筛管和血管形成、合点细胞核的消失、小维管束的横截面积存在显着差异，被认为是重要的形态学特征。小麦淀粉和养分积累差异的解剖学基础.