The Development Of Protein Bodies In Different Regions Of The Wheat Endosperm And Their Responses To Nitrogen And Drought Stress

This study aimed to reveal the development of protein bodies (PBs) in different regions of winter wheat (Titicum aestivum) endosperm and their responses to nitrogen (N) and drought stress. In this study, strong gluten wheat, medium gluten wheat and weak gluten wheat were used as experimental materials; resin semi-thin section technology, optical microscopy, physiological measurement and image-analysis software Image-Pro Plus were applied to investigate PBs in subaleurone cells and central endosperm cells in different regions including dorsal, ventral, and lateral parts of the wheat endosperm based on morphological characteristics. The results were as follows:1.The accumulation rate of protein bodies and storage protein in endosperm increased slowly at the early stage but rapidly later and finally reached to stabilization. From 7 DAF to 20 DAF, the protein content of wheat endosperm increased rapidly, but after 20 DAF, it increased slowly. The size, area and development of protein bodies in endosperm among wheat cultivars were the order of strong gluten wheat> medium gluten wheat> weak gluten wheat, further, the values were significant (P<0.05) at 8 DAF,11 DAF and 14 DAF. The amount and relative areas of PBs in the subaleurone cells were larger than those in the central endosperm cells. These differences also varied in terms of the position in the endosperm. In particular, the proportion of PBs in the ventral part was evidently larger than that in the dorsal part. The distribution of protein bodies and starch granules varied among different mature wheat cultivars. The protein bodies in quantities in strong gluten wheat were most numerous and they were combined with starch granules compactly, but the contrary was observed in weak-gluten wheat cultivar. The appearances of medium gluten wheat cultivar were shown between the two varieties above.2.The protein content of wheat endosperm was significantly increased by N application in the two wheat cultivars, especially at the middle developmental stages of wheat, and N made the protein bodies in wheat endosperm accumulate earlier. N not only increased the amount and relative areas of PBs significantly in the two wheat cultivars but also changed the accumulation pattern of PBs. The control endosperm mainly contained smaller PBs that were distributed unevenly in endosperm cells; by contrast, N-treated endosperm contained numerous larger PBs or aggregations that were concentrated in a particular region of the endosperm cells. Furthermore, the degree of response to N of these varieties differed:strong gluten wheat> weak gluten wheat. The accumulation of PBs in different regions of wheat endosperm responsed differently to N, as lateral region> dorsal region> ventral region.3.Drought stress could increase the protein content of wheat endosperm, especially from 12 DAF to 18 DAF. The amount and relative areas of PBs in subaleurone cells and central endosperm cells in different regions under drought stress all increased.The way that protein bodies gathered also changed at the same time.The endosperm withoutdrought stress mainly contained smaller PBs that were scattered in endosperm cells in an unordered pattern, whereas the endosperm under drought stress contained many larger PBs or aggregations that were concentrated in a certain region of endosperm cells. The degree of response to drought stress among these varieties differed:xumai 33> ningmai 13,also,the accumulation of PBs in different regions of wheat endosperm responsed differently to drought stress:lateral region>ventral region>dorsal region.