Wx基因近等基因系水稻稻米淀粉性质差异及其对后期氮肥的响应

发布时间：2018-09-04 16:24

【摘要】：社会的发展和经济的进步对水稻种植业提出了新的要求,兼顾提高水稻产量和改善稻米品质同步发展,已经成为新时期水稻生产的主要发展方向。Wx基因是控制稻米品质的关键基因之一,其在遗传学和分子生物学方面的的分析较为透彻,但在群体条件下系统分析Wx基因的表达效应尚未得到有效开展。本试验以不同Wx基因(Wxa、Wxin、Wxb、wx)近等基因系为供试材料,设置了结实期不同的氮肥处理,观察不同Wx基因型水稻稻米淀粉性质特征及其对后期氮肥的响应,并尝试从基因表达与环境互作的角度去分析稻米品质的环境效应及其形成机制,得到对后期施肥影响稻米品质的准确认识,为优质栽培调控体系提供必要理论依据。主要结果如下:1、不同Wx基因型水稻两年的产量高低一致表现为WxaWxinWxbwx基因型。同时,各基因型对后期氮肥的反应有所差异,Wxa、Wxin基因型随后期氮肥的增加表现较大的增产幅度。Wxa基因型水稻的有效穗数、千粒重表现较高,结实率相对较低;每穗粒数以Wxin、wx基因型水稻相对较高,Wxb基因型最低。Wxa、Wxin基因型水稻结实期干物质积累较高,Wxb基因型相对较低。少量施肥即可引起籼型Wxa基因型水稻产量的显著增加,而粳型Wxb基因型水稻对后期施肥表现相对不敏感。2、在糯型水稻(wx基因型)中导入不同Wx基因,显著提高稻米的糙米率、精米率。后期氮肥施用一定程度上改善了稻米的加工品质和外观品质;稻米直链淀粉含量和胶稠度因Wx基因型的不同产生显著差异,呈现明显的籼、粳型品质特征。随着施氮量的增加,表观直链淀粉含量增加,胶稠度变短,崩解值、最高粘度下降,消减值、峰值时间增加,蒸煮品质呈现显著下降的变化,且低氮水平条件下的氮肥增加更容易导致稻米品质的明显下降。Wxa、Wxin基因型水稻对后期施肥的反应较Wxb、wx基因型更为敏感。3、导入Wx基因后,小型淀粉粒和中型淀粉粒所占的体积百分比增加,大型淀粉粒所占的体积百分比降低。淀粉粒表面积和数量所占的百分比表现出,非糯性材料比糯性材料具有更高比例的小型淀粉粒和较低比例的中型和大型淀粉粒。小型淀粉颗粒所占的体积百分比与糊化特征呈显著负相关;大型淀粉粒所占体积百分比与各糊化特征值呈显著正相关。随着后期施氮量的增加,各材料小型淀粉粒所占体积、表面积、数量百分比呈增加趋势,中型淀粉粒与小型淀粉粒变化趋势相反。小型淀粉颗粒的增加,中型淀粉颗粒的降低,使得淀粉糊化所需的热量减少,糊化热焓值降低。4、支链淀粉结构在不同Wx基因型间存在明显差异,分支度大小表现为WxWxbWxinWxa,显示越趋向籼型,短链比例越少的趋势。淀粉结晶度、膨胀势等也呈现相应变化。稻米直链淀粉含量和崩解值、糊化温度呈显著负相关,与最终粘度、消减值、回复值、峰值时间呈显著正相关。支链淀粉分支度与各指标呈现相反的相关关系。淀粉结构对后期氮肥的反应总体上籼型Wa材料以短链比例降低,粳型Wxb材料中长链比例增加为显著特征,结果均导致淀粉分支度的降低。淀粉结晶度和膨胀势随着后期氮肥水平的提高而降低,与直链淀粉呈显著负相关,与支链淀粉分支度呈显著正相关。5、不同基因型Wx基因的表达强度变化动态基本一致,在强势粒中,抽穗后Wx基因表达量不断增加,抽穗后10d左右达到表达高峰,抽穗后15d开始下降。而弱势粒在抽穗后20d尚处于表达增加的过程。各材料GBSS活性与Wx基因表达量呈显著正相关。随着后期施肥水平的提高,Wxa、Wxin基因表达量显著增加,wx基因表达量总体上很低,对后期施肥相对不敏感,GBSS活性呈现相应变化。
[Abstract]:The development of society and the progress of economy have put forward new requirements for rice planting. The simultaneous development of increasing rice yield and improving rice quality has become the main development direction of rice production in the new era. In this experiment, the near isogenic lines of different Wx genes (Wxa, Wxin, Wxb, wx) were used as test materials, and different nitrogen fertilizer treatments were set up to observe the starch properties of different Wx genotypes of rice and their response to nitrogen fertilizer at later stage. The main results are as follows: 1. The yield of rice with different Wx genotypes in two years is consistent with that of WxaWxin Wxbwx genotype. At the same time, the response of Wxa and Wxin genotypes to nitrogen fertilizer was different, and the yield of Wxa and Wxin genotypes increased greatly in the following period. The Wxb genotype was relatively low, but the Wxb genotype was relatively insensitive to late fertilization. 2. Different Wx genes were introduced into waxy rice (wx genotype) to significantly increase the brown rice rate and milled rice rate. The amylose content and gel consistency of rice were significantly different from those of Wx genotype, showing obvious indica and japonica quality characteristics. Wxa and Wxin genotypes were more sensitive to late fertilization than Wxb and Wx genotypes. 3. The percentage of small starch grains and medium starch grains increased after the introduction of Wx gene. The volume percentage of large starch granules decreased. The surface area and quantity percentage of starch granules showed that non-waxy materials had higher proportion of small starch granules and lower proportion of medium and large starch granules than waxy materials. The volume percentage of small starch grains was positively correlated with the gelatinization characteristics. With the increase of nitrogen application rate, the volume, surface area and quantity percentage of small starch grains increased, while that of medium starch grains was opposite to that of small starch grains. The branching degree of amylopectin was WxWxbWxinWxa, indicating that the more indica type, the less short chain proportion. The starch crystallinity, swelling potential and so on also showed corresponding changes. The amylopectin content and disintegration value of rice, gelatinization temperature were obvious. The branching degree of amylopectin was inversely correlated with each index. The reaction of starch structure to nitrogen fertilizer in late stage was generally characterized by the decrease of short-chain ratio in indica wa materials and the increase of long-chain ratio in Japonica Wxb materials. Starch crystallinity and swelling potential decreased with the increase of nitrogen fertilizer level in the late stage, negatively correlated with amylopectin, and positively correlated with amylopectin branching degree. 5. The dynamic changes of Wx gene expression intensity of different genotypes were basically the same. In strong grains, Wx gene expression increased after heading and left 10 days after heading. GBSS activity was positively correlated with Wx gene expression. With the increase of fertilization level, Wxa and Wxin gene expression increased significantly, Wx gene expression was generally very low, and was relatively insensitive to late fertilization. SS activity showed corresponding changes.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S511

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