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The mesocotyl, a structure located between the basal part of the seminal root and the coleoptile node of seedlings, contributes to pushing the shoot tip through the soil surface, a function that is essential for the uniform emergence of direct-seeded rice. Its elongation is inhibited by light and induced in darkness. This investigation of an indica rice (P25) with vigorous mesocotyl elongation was aimed at identifying the “omics” basis of its light-induced growth inhibition. A transcriptomic comparison between mesocotyl tissues that had developed in the dark and then been exposed to light identified many differentially expressed genes (DEGs) and differentially abundant microRNAs (miRNAs). Degradome sequencing analysis revealed 27 negative miRNA-target pairs. A co-expression regulatory network was constructed based on the miRNAs, their corresponding targets, and DEGs with a common Gene Ontology term. It suggested that auxin and light, probably antagonistically, affect mesocotyl elongation by regulating polyamine oxidase activity.

OsPho1 in Zhonghua 11 (ZH11) was edited using the clustered regularly interspaced short palindromic repeats- associated endonuclease 9 (CRISPR/Cas9) system. Two homozygous T1 mutants (cr-pho1-34 and cr-pho1-37) displayed a chalky endosperm with a white core, which significantly decreased 1000-grain weight. In addition, many rounded starch granules and abnormal amyloplasts were present in the central region of mutant endosperm cells with increased amylose and lipid contents, decreased total protein content, and altered physicochemical properties of starch. The OsPho1 protein is localized in chloroplasts, and quantitative real-time PCR (qRT-PCR) and β-glucuronidase (GUS) staining indicated that OsPho1 was highly expressed in seeds at 5 d after fertilization (DAF). OsPho1 mutations displayed close relationships with plastidial phosphoglucomutase and ADP- Glc pyrophosphorylase based on α-D-glucose-1P at different temperatures. Moreover, the expressions of starch metabolism- related genes were also altered in the mutant, and the over- expression of OsPho1 may cause grain chalkiness.

The growth, development, and quality of rice are inhibited by the presence of cadmium (Cd) in the soil, the uptake of which depends strongly on the pH of the growth medium. Here, a hydroponics-based experiment was conducted to characterize the relationship between Cd accumulation and the pH of the medium in seedlings of the two cultivars, Zhonjiazao17 (ZJZ17) and Xiangzhengyu (XZY). The uptakes of Cd by the roots of both cultivars and its translocation to the shoots were the highest from a medium of pH 6.0. XZY plants accumulated more Cd than ZJZ17 ones. Transcription profiling indicated that the genes, OsNRAMP1 and OsHMA2, were actively involved in Cd uptake and transport, as they were both strongly upregulated at pH 6.0. Both the Cd concentration of the medium and its pH exerted significant effects on the seedling growth. At pH 6.0, zinc was efficiently transported, but the translocation of iron was suppressed in shoot. The genes, OsZIP5 and OsYSL15, are the most likely responsible for the uptake and translocation of both these elements in rice seedlings.

The cadmium (Cd) and lead (Pb) content in both white and wholemeal flour milled from 110 leading rice cultivars was assessed. The white flour Cd content ranged from

The major storage substance in rice endosperm is starch, which accounts for 80% of dry matter weight. In this study, rice mutant flo7, selected from the progeny of Nipponbare's tissue culture, displayed floury and opaque endosperm. Compared with its corresponding wild type (WT) Nipponbare, the mutant flo7 produced longer, narrower, thinner and lighter grains. The levels of glucose, fructose and sucrose in the mutant flo7 endosperm were higher than those in the WT endosperm, whereas the protein content was not affected. With respect to both amylose content and gel consistency, the mutant flo7 was lower than WT, but its alkali value was higher. Scanning electron microscopic examinations showed that the endosperm of the mutant flo7 contained irregular, loosely packed and compound starch granules. Genetic analysis indicated that the mutant phenotype was determined by a single recessive nuclear gene. The flo7 locus was mapped to a region on the long arm of chromosome 12, within a 95.1 kb interval defined by the markers C2-11 and C5-15. There are 13 open reading frames in the mapping interval. Transcription profiling of the developing grains showed that a number of genes involved in starch synthesis were affected differently in the mutant flo7.

Rice vermicelli is a main food consumed in China and Southeast Asia. Quality of rice vermicelli varies with rice cultivars. Parameters including amylose content, amylopectin distribution, thermal and pasting characteristics, gel texture and starch granules of three rice cultivars “Zhongjiazao 17”, “Xiangzaoxian 24” and “Thai Jasmine Rice”, were studied for their impacts on vermicelli quality. Results showed significant differences for the measurements of the quality traits and indicated that a favorable quality of vermicelli was not determined by any single factor instead of a combination of multi-parameters. A vermicelli with a favorable quality could be produced from a rice variety with a high apparent amylose content (>25%), a protein content of 11%, an intermediate gelatinization temperature and gel consistency, and a gel hardness (~3 N for a Rapid Viscosity Analyzer pasting) and moderate retrogradation capacity (a setback viscosity of 30–100 RVU).

Near-infrared reflectance spectroscopy (NIRS) has been used to predict the cooking quality parameters of rice, such as the protein (PC) and amylose content (AC). Using brown and milled flours from 519 rice samples representing a wide range of grain qualities, this study was to compare the calibration models generated by different mathematical, preprocessing treatments, and combinations of different regression algorithm. A modified partial least squares model (MPLS) with the mathematic treatment "2, 8, 8, 2" (2nd order derivative computed based on 8 data points, and 8 and 2 data points in the 1st and 2nd smoothing, respectively) and inverse multiplicative scattering correction preprocessing treatment was identified as the best model for simultaneously measurement of PC and AC in brown flours. MPLS/"2, 8, 8, 2"/detrend preprocessing was identified as the best model for milled flours. The results indicated that NIRS could be useful in estimation of PC and AC of breeding lines in early generations of the breeding programs, and for the purposes of quality control in the food industry.