| With the improvement of living standard, the emphasis on yield and rice quality increase synchronously and rice quality is more and more important. For edible rice, eating and cooking quality are paid particularly attention. Amylose content, gel consistency and gelatinization temperature largely determine the cooking and eating quality performance. Wx gene codes GBSS I and its expression determines the performance of amylose content in rice endosperm. However, it has not well known about the impact of environmental effects on Wx gene. The mechanism of effects about cultural environment on rice quality is unclear. This study set near-isogenic lines of Wx genes as test materials, applied water and panicle fertilizers in different ways, changed growth conditions during productive phase, analyzed the differences of yield, physiological characteristics, rice quality and crystal properties among Wx alleles and the effects of cultivation environment. Analyze the relationships of differences of gene expressions with cooking and eating quality, from the gene expression level to the physiological and biochemical level, and research to the mechanism of environmental effects from new angle. Through the research, it is possible to provide the necessary theoretical basis and new feasible way to tuning cultivation in rice. The main results are as follows:With the improvement of living standard, the emphasis on yield and rice quality increase synchronously and rice quality is more and more important. To edible rice, eating and cooking quality are paid particularly attention. Amylose content, gel consistency and gelatinization temperature largely determine the cooking and eating quality performance. Wx gene codes GBSS I and its expression determines the performance of amylose content in rice endosperm. However, it has not been well known about the impact of environmental effects on Wx gene. The mechanism of effects about cultural environment on rice quality is unclear. This study set near-isogenic lines of Wx genes as test materials, applied water and grain fertilizer in different ways, changed growth conditions during grain filling stage, analyzed the differences of yield, physiological characteristics, rice quality and crystal properties among Wx alleles and the effects of cultivation environment on them above-mentioned. Analyze the relationships of differences of gene expressions with cooking and eating quality, from the gene expression level to the physiological and biochemical level, and research to the mechanism of environmental effects from new angle. Through the research, it is possible to provide the necessary theoretical basis and new feasible way to tuning cultivation in rice. The main results are as follows:1. There existed significant difference among Wx alleles in terms of yield:the yield of Wxa and Wxin was higher, while Wxb and wx were relatively lower, in which Wxa gene presented the highest yield level in most cases. The sequence of 1000-grain weight was:Y5 (Wxa-2)>Y3 (Wxa-1)>Y7(Wxin)>Y1 (Wxb)>Y9(wx). Wxa allele had the higher quantity than Wx and wx alleles on panicles. The number of spikelet per panicle of Wxin and wx was more enormous than others. Root activity and photosynthetic rate of Wxa and Wxin were higher than the other Wx alleles during grain filling. There was genotype difference as for the reaction of Wx alleles to cultivation environment:Wx’" and wx were insensitive to fertilizer, Wxb and Wxa were sensitive to fertilizer and the yield of Wxb increased obviously under the soil water stess (-30kpa). Wx gene had the noticeable function to reproductive growth and yield formation as well.2. Wx gene had no obvious impact on milling quality and had restrictions on the appearance quality. There was a great difference in exterior quality among Wx alleles: length/width of Wxb was superior to the other materials while the numerical value of wx was smaller. The results showed that chalky rice rate and chalkiness of Wxb were best and Wx-1 were worst in the Wx alleles. Protein of wx was lowest. Amylose content was found to be determined by different Wx alleles. Wxa had high AC and Wx-1 had moderate AC, while wx almost had little AC. AS for GC, Wx alleles differed greatly, wx had longest GC, Wxb was secondly and GC of Wxa came the last. It showed that GC and AC were significantly negative correlation and Wx gene was the regulator gene or major gene of GC. Difference on characteristics of RVA profile was very essential. Viscosity of Wxb was high and wx was very low. Wxb had the most amazing value of BDV, followed by wx and Wx’-, and Wxa was minimal. Wx gene had the key factor influcing the characteristics of RVA profile. DSC of different Wx alleles differed significantly. Wxa and Wxin exhibited lower DSC specific value (TP、T0、TC)than Wxb、wxby4℃3. The difference of granule distribution among Wx alleles was obvious, wx had no complete peak between 0-2um. Starch average granule diameter of wx and Wxb was smaller than the others.The main reason was the percentage value ofwx and Wxb between 0-5um was bigger and leading the curve to move to the left. Starch average granule diameter value of Wxa、Wxin turns to be larger. Grain fertilizer increased the percentage of big starch granule and made average granule diameter bigger. Starch average granule diameter was significantly positive correlated with 1000-grain weight as well. Wx genes controlled the synthesis of amylose and amylose content affected the growth of starch grains, changed the 1000-grain weight and affected yield.4. Wx alleles starches exhibited A-type XRD spectra with major diffraction peaks at about 15,17,18 and 23°2θ, which agreed with the XRD patterns of normal cereal starches. Thus it was clear that different Wx alleles and environment could not make difference on crystal type. The difference of crystallinity among Wx alleles was obvious. Crystallization area ofwx was largest, followed by Wxb and the crystallization area of Wxa and Wxin was smallest. Except wx, the relative crystallinity of the other 4 Wx alleles was seriously negative correlation with the amylose content. In terms of short and long branch-chains, the highest content was wx, followed by Wxb, Wxin and Wxa had the minimum content. The results showed that increasing the grain fertilizer properly could promote the starch gelatinization process because it reduced the short branch-chains, added the long branch-chains and amylose content. The short branch-chains increased, long branch-chains and amylose content reduced under the soil water stress (-30kpa). The normalized chromatograms of branch-chain length distribution of debranched amylopectin were analyzed by HPAEC. The chain-length distributions of amylopectin from Wx alleles were basically identical:they were similar to normal distribution and two peaks were observed at the position of 11 and 45 DP. A distinct difference of value was observed among the Wx alleles starches. The average chain length of amylopectin of Wxa and Wxin was higher than the others... |
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