Variability in amylose content of Bangladeshi rice cultivars due to unique SNPs in Waxy allele

Unearthed New Indel in the Waxy Gene in Glutinous Rice Landraces from Thailand

<b>Background and Objective:</b> Glutinous rice landraces have played important role in northeastern and northern region of Thailand and the Lao People's Democratic Republic (PDR) by ethnic groups in this area, both as staple food and ritual in rice culture since ancient times. At a present number of these rice, cultivars have decreased and disappeared from villages without considerations and/or explore DNA variation. This study compared target DNA sequences of <i>waxy</i> genes of a collection of glutinous rice landraces both upland and lowland rice. <b>Materials and Methods:</b> A collection of 50 glutinous rice landraces was explored DNA variation in the <i>Waxy</i> gene by re-sequencing DNA of the two segments (i.e., promoter, exon1 and intron1) of a gene. <b>Results:</b> New InDel of two deletion G at position 11 (GG-) and C at position 15 (CC-) were observed in DNA sequences of the promoter region and 5'untranslalted region of both upland and lowland rice accessions. Further, the (CT)<sub>17</sub> and (CT)<sub>18</sub> were two alleles in these glutinous rice landraces from northern and northeastern Thailand. All glutinous rice landraces exhibited a characteristic of low amylose content or glutinous rice: T Single Nucleotide Polymorphisms (SNP) (AGTTATA) in the first intron splice site. <b>Conclusion:</b> New InDel in DNA sequences of the promoter region of the <i>waxy</i> gene in glutinous rice landraces was first reported. This implies that it may reflect the status of genetic background in glutinous rice landraces in Thailand.

Starch Components, Starch Properties and Appearance Quality of Opaque Kernels from Rice Mutants

Rice mutants with altered starch components and properties are important genetic resources in rice breeding programmes. In this study, 44 mutants with altered starch components were screened from 135 rice mutants with opaque kernels using a starch–iodine absorption spectrum method, and nine mutants from them were further selected for investigating their starch properties and kernel appearance quality. The results showed that the iodine absorption spectrum parameters, OD620, OD620/550, and λmax, could reflect the changes of starch components in rice mutants, and had significantly positive relationships with amylose content and negative relationships with the proportion of short branch-chains of amylopectin. The endosperm starches from nine mutants all showed A-type crystalline structure and similar short-range ordered structure, but had different relative crystallinities. The changes of starch components in mutants not only resulted in the different gelatinization properties of starch but also changed the appearance quality of brown rice kernels. This study provided abundant genetic plants for studying the molecular mechanism of starch synthesis and the quality regulation of rice kernels.

Carbohydrate reserves and seed development: an overview

Seeds are one of the most important food sources, providing humans and animals with essential nutrients. These nutrients include carbohydrates, lipids, proteins, vitamins and minerals. Carbohydrates are one of the main energy sources for both plant and animal cells and play a fundamental role in seed development, human nutrition and the food industry. Many studies have focused on the molecular pathways that control carbohydrate flow during seed development in monocot and dicot species. For this reason, an overview of seed biodiversity focused on the multiple metabolic and physiological mechanisms that govern seed carbohydrate storage function in the plant kingdom is required. A large number of mutants affecting carbohydrate metabolism, which display defective seed development, are currently available for many plant species. The physiological, biochemical and biomolecular study of such mutants has led researchers to understand better how metabolism of carbohydrates works in plants and the critical role that these carbohydrates, and especially starch, play during seed development. In this review, we summarize and analyze the newest findings related to carbohydrate metabolism's effects on seed development, pointing out key regulatory genes and enzymes that influence seed sugar import and metabolism. Our review also aims to provide guidelines for future research in the field and in this way to assist seed quality optimization by targeted genetic engineering and classical breeding programs.