Project description:A deeper understanding of the genetics of rice grain starch structure is crucial in tailoring grain digestibility and ensuring cooking quality to meet consumer preferences. Significant association peaks on chromosomes 6 and 7 were identified through genome-wide association study (GWAS) of debranched starch structure from grains of a 320 indica rice diversity panel using genotyping data from the high-density rice array. A systems genetics approach that interrelates starch structure data from GWAS to functional pathways from a gene regulatory network identified known and novel genes with high correlation to the proportion of amylose and amylopectin. A novel SNP in the promoter region of Granule Bound Starch Synthase I (GBSS I) was identified along with seven other SNPs to form haplotypes that discriminate samples into different phenotypic ranges of amylose. A novel GWAS peak on chromosome 7 between LOC_Os07g11020 and LOC_Os07g11520 indexed by a non-synonymous SNP mutation on exon 5 of a bHLH transcription factor was found to elevate the proportion of amylose at the expense of reduced short-chain amylopectin. Linking starch structure with starch digestibility by determining the kinetics of cooked grain amylolysis of selected haplotypes revealed strong association of starch structure with estimated digestibility kinetics. Combining all results from grain quality genomics, systems genetics, and digestibility phenotyping, we propose novel target haplotypes for fine-tuning starch structure in rice through marker-assisted breeding that can be used to alter the digestibility of rice grain, thus offering rice consumers a new diet-based intervention to mitigate the impact of nutrition-related non-communicable diseases.
Project description:Waxy starch has an important influence on bread dough and the qualities of breads. Generally, grain weight and yield in waxy wheat (Triticum aestivum L.) are significantly lower than in bread wheat. In this study, we performed the first proteomic and phosphoproteomic analyses of starch granule-binding proteins by comparing the waxy wheat cultivar Shannong 119 and the bread wheat cultivar Nongda 5181. The waxy and non-waxy wheats had similar starch granule morphological features and developmental patterns, and similar amylopectin quality in the grain. These results indicate that reduced amylose content does not affect amylopectin synthesis, but it causes significant reduction of total starch biosynthesis, grain size, weight and yield. Two-dimensional differential in-gel electrophoresis identified 40 differentially expressed protein (DEP) spots in waxy and non-waxy wheats, which belonged mainly to starch synthase (SS) I, SS IIa and granule-bound SS I. Most DEPs involved in amylopectin synthesis showed a similar expression pattern during grain development, suggesting relatively independent amylose and amylopectin synthesis pathways. Phosphoproteome analysis of starch granule-binding proteins, using TiO2 microcolumns and LC-MS/MS, showed that the total number of phosphoproteins and their phosphorylation levels in ND5181 were significantly higher than in SN119, but proteins controlling amylopectin synthesis had similar phosphorylation levels. Dynamic transcriptional expression profiling of starch biosynthesis-related genes indicated similar transcriptional expression profiles in both cultivars. Our results revealed that phosphorylation modifications played critical roles in amylose and amylopectin biosynthesis, but the lack of amylose did not affect the expression and phosphorylation of the starch granule-binding proteins involved in amylopectin biosynthesis.
Project description:Waxy starch has an important influence on the qualities of breads. Generally, grain weight and yield in waxy wheat (Triticum aestivum L.) are significantly lower than in bread wheat. In this study, we performed the first proteomic and phosphoproteomic analyses of starch granule-binding proteins by comparing the waxy wheat cultivar Shannong 119 and the bread wheat cultivar Nongda 5181. These results indicate that reduced amylose content does not affect amylopectin synthesis, but it causes significant reduction of total starch biosynthesis, grain size, weight and grain yield. Two-dimensional differential in-gel electrophoresis identified 40 differentially expressed protein (DEP) spots in waxy and non-waxy wheats, which belonged mainly to starch synthase (SS) I, SS IIa and granule-bound SS I. Most DEPs involved in amylopectin synthesis showed a similar expression pattern during grain development, suggesting relatively independent amylose and amylopectin synthesis pathways. Phosphoproteome analysis of starch granule-binding proteins, using TiO2 microcolumns and LC-MS/MS, showed that the total number of phosphoproteins and their phosphorylation levels in ND5181 were significantly higher than in SN119, but proteins controlling amylopectin synthesis had similar phosphorylation levels. Our results revealed the lack of amylose did not affect the expression and phosphorylation of the starch granule-binding proteins involved in amylopectin biosynthesis.
Project description:The grains of mutant hrsc1 exhibited a severe chalkiness phenotype relative to its wild type QZ-10. Physiological measurements and scanning electron microscopy observation further indicated that hrsc1 grains contain oval irregular starch granules, as well as significantly increased RS (up to 14-fold), amylose (up to 1.6-fold), lipid (up to 3-fold) and protein (up to 1.2-fold) contents. Dynamic proteome of grains were analyzed on four different development stages (DAF 6d, 12d, 18d and 24d) during filling stage between hrsc1 and QZ-10.
Project description:Cereal crops accumulate starch in seeds as an energy reserve. Sucrose synthase (SuSy) plays an important role in grain starch synthesis. In this study, ZmSUS1 was transformed into maize inbred line KN5585, and transgenic plants were obtained. Compared with the control, the content and activity of SuSy were significantly increased, the amylose content in mature seeds of transgenic maize increased by 41.1-69.2%, the total starch content increased by 5.0-13.5%, The 100-grain weight increased by 19.0-26.2% and the average diameter of starch granules increased by 10.8-17.2%. These results indicated that overexpression of ZmSUS1 can significantly improve the traits of maize kernels and obtain new lines with high amylose content. It was also found that ZmSUS1 may increase the amylose content by regulating the expression of Shrunken2 (Sh2) and Brittle2 (Bt2) which encodes endosperm ADP-glucose pyrophosphorylase (AGPase) size subunits, and the expression of Granule bound starchsynthase1 (GBSS1) and Starch synthase1 (SS1) which encodes starch synthase. This study proved the important role of ZmSUS1 in maize starch synthesis, and provided a new technology strategy for improving corn starch content and yield.
Project description:We aimed to identify differentially expressed miRNAs during wheat grain development by using high-throughput sequencing approach. Four small RNA libraries were constructed from wheat grains collected at 7, 14, 21 and 28 days post anthesis (DPA). A total of 165 known miRNAs and 37 novel miRNAs were identified in four small RNA libraries. Moreover, a miRNA-like long hairpin locus was first identified to produce 21~22-nt phased siRNAs. A comparison of the miRNAomes revealed that 55 miRNA families were differentially expressed during the grain development. Examination of 4 different small RNA expression profilings in the 4 developmental stages of wheat grains.