The present results provide new knowledge about the influence of different Wx alleles on the structural and physicochemical properties of rice starch. © 2016 Society of Chemical Industry.

The Waxy locus is the major locus controlling AM synthesis in rice endosperm. . Through Waxy genotype association analysis, functions of the four Waxy nucleotide polymorphisms on rice starch properties were determined. Analysis of correlation among the cooking and pasting parameters indicated that most of the traits were significantly correlated. The present results have important implications for rice breeders to select favorite Waxy alleles in rice grain quality improvement.

The Wx gene is the major gene controlling amylose synthesis in rice endosperm. So far, the Wx gene can be mainly classified into five common alleles, wx, Wx t , Wx g1 , Wx g2 , and Wx g3 , according to their amylose phenotypes. Besides, the Wx allelic variation was also found to play an important role in regulating other physicochemical properties of rice starch. However, the specific physiological and starch structural mechanisms are not clear yet. With a set of singlesegment substitution lines harboring five different Wx alleles, the genotype differences in amylopectin structure and dynamic changes of activities of key starch synthesis enzymes were investigated. The distinct Wx genotype difference in chain length distribution of amylopectin was confirmed by size exclusion chromatography. There were clear allelic differences in activities of starch synthesis enzymes during grain filling. The Wx allelic variation had the highest impact on the activities of starch branching enzyme, followed by pullulanase, and soluble starch synthase, while no influence on isoamylase activity. Differences in structural features of amylopectin and mean enzyme activities during grain filling period correlated well with most of the variations in starch property traits. These findings indicate that the Wx allelic variation may affect starch structure and physicochemical properties through selectively influencing activities of starch synthesis enzymes in developing rice grains. The present results will contribute to our understanding of the regulation of starch biosynthesis in rice endosperm.

In this paper, the following contents including the original receptor E1213 and other two control materials, RAPD polymorphism, photosynthetic efficiency, and the number of vascular bundles of the first internodes below the peduncle have been studied for the eight F7 transgenic lines obtained from ion beam implantation. The results showed that there was a significant variation in genomes of maize-rice line, compared with the receptor EI213, after the total exogenous maize DNA was introduced into EI213. The number of the vascular bundles of maize-rice progeny's lines was obviously much larger than those of the original receptor E1213 and other two controls GER-3 and MH63, and along with the photosynthetic efficiency of maize-rice progeny's lines being gone up. Moreover, the parenchyma cells around the vascular bundles of the transgenic lines became much larger in number and in size than those around the controls. All these indicated that the maize-rice progeny's lines are really different from and superior to the receptor and the controls. It is a novel and useful way to apply ion beam implantation in transferring DNA from Cq plant maize into C3 plant rice.

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