Pericarp Rice Research Articles

Assessment of antioxidant properties in selected pigmented and non-pigmented rice (Oryza sativa L.) germplasm and determination of its association with Rc gene haplotypes

BackgroundAntioxidant properties of rice provide various health benefits due to its ability to inhibit cellular oxidation. Antioxidant content of rice is known to be linked with the pericarp pigmentation. The Rc gene of rice (Os07g0211500) codes for a basic helix-loop-helix (bHLH) protein, acting as a transcriptional factor in regulating proanthocyanidin biosynthesis. The current study was carried out to evaluate the variation of antioxidant properties in a selected panel of rice accessions and assess the possibility of using haplotypes defined based on the Rc gene to predict pericarp pigmentation and antioxidant content in rice.ResultsThirty-two rice accessions were evaluated for grain pericarp colour and antioxidant properties; total phenolic content (TPC), total flavonoids (TFC), proanthocyanidins (PAC) and radical scavenging activity (RSA). The parameters TPC, TFC and PAC showed significant positive correlation with RSA (r > 0.69; P < 0.01). The study panel showed a wide variation for antioxidant properties and rice accessions such as Sudu Heenati, Deweraddiri, Madathawalu, Masuran, Ld 368, At 311, Kalu Heenati, Bw 272-6B, Pokkali, At 362 and Wanni Dahanala exhibited profound potential with respect to antioxidant properties. Based on three-target sites previously reported as critical for the function of the coded bHLH protein (an A/C SNP at 1,353-bp, a 1-bp insertion/deletion at 1,388-bp, and a 14-bp insertion/deletion at 1,408-1,421-bp positioned in the mRNA corresponding to the exon 6 of rice Rc gene), three haplotypes were defined (H1-H3). Pigmentation of the rice pericarp could be successfully explained based on the defined haplotypes (H1 (C/G/+): red, and H2 (A/G/+) and H3 (C/G/-): white), and the H1 haplotype corresponded to a significantly (P < 0.05) higher TPC, TFC, PAC and RSA compared to the other haplotypes.ConclusionsThe studied rice accessions showed a significant variation with respect to antioxidant properties. Haplotype H1 defined based on the three-target sites in the exon 6 of Rc gene can detect rice accessions with red pigmented pericarp and high antioxidant properties effectively. Hence, its use can be recommended as an alternative to biochemical assays for screening during rice breeding programs.

Antioxidants Characteristics of Traditional Cultivars of Rainfed rice (oryza glaberrima) from Goh-Djiboua and Mountains Districts in Côte D’ivoire

The antioxidant compounds in foodstuffs are of great interests for the nutritional and health safety of consumers, given the preponderant role of food in the overall health. The current work focusses the main antioxidant compounds and activities from 27 traditional varieties of rainfed rice. Qualitative tests were performed to check the presence of the antioxidant compounds, namely total polyphenols, flavonoids, tannins, alkaloids, saponins, sterols and terpenes, probed and measured from raw brown rice or whole grains using standard methods. In addition, the antioxidant activity was investigated using standard ABTS and DPPH methods. Only total polyphenols and, to a lesser degree, flavonoids, were qualitatively found from the studied rice samples. The total polyphenols contents (43.83 to 194.60 mg GAE/100g) and flavonoids contents (16.08 to 124.83 mg QE/100g) displayed significant differences from the traditional rainfed rice cultivars investigated (P&lt;0.05), recording higher values in the grains of coloured pericarp rice compared to the other varieties. The greatest ABTS content is found in the varieties Sipricri (357.51 µM Trolox Eq/g) and Jbröko (137.85 µM Trolox Eq/g) which respective percentages of degradation of ABTS radicals are 52.95% and 20.09%. Regarding DPPH assay, the lowest EC50 is found from the variety Sipricri (36.07 µM Trolox Eq/g) and the highest with the rice Glawlon (3445.84 µM Trolox Eq/g). The antioxidant trend of the rainfed rice is nutritionally favorable to support a safety food diet using rice as common local food stuff for populations.

Genetic variability of mutant rice (Oryza sativa) genotype induced by gamma rays

Abstract. Ishak I. 2023. Genetic variability of mutant rice (Oryza sativa) genotype induced by gamma rays. Biodiversitas 24: 3300-3306. Rice seeds of Sidenuk cultivars were irradiated by gamma rays creating a broad spectrum of genetic variability among individual plants at M3 generation progeny. Gamma Irradiated seeds created Mutation among the somatic cells population in mature embryos at M1 generations. Somatic cell mutation influenced the genetic structures of gametes cells formation on gametogenesis at M1 plants. Observation of M2 plants showed that black and brown colors of rice's pericarp were found with rice's lemma, and palea color was different compared to the wild type (Sidenuk cultivars). Seven plants with black rice pericarp colors out of 330 were obtained at M2 plants. Chlorophyll mutation was observed at M4 generation; the results showed that chimera, green, and albino leaf blade was obtained in several individual plants. There were also the variability of Palea and lemma colors among individual plant such as green, white, and purple. The cellular biology approach will explain these mutations before molecular biology identification is made.

Comparative Biochemical and Transcriptome Analyses Reveal Potential Candidate Genes Related to Pericarp Browning in Red Rice

Proanthocyanidins (PAs) are major phytochemicals in rice, and accumulate abundantly in red pericarp (RP) rice. Consumers and rice breeders are increasingly showing interest in PAs because of their beneficial health effects; however, PA biosynthesis in rice is not well-understood. Therefore, to gain insights into this process, we performed comparative transcriptome analysis of grains harvested at 14 days after flowering (DAF; i.e., the stage at which active PA biosynthesis occurs without pericarp color change) and 28 DAF (the stage of late seed development with pericarp color change) from RP and white pericarp rice. In RP rice at 14 DAF, the expression levels of six structural genes (OsCHS, OsF3H, OsF3′H, OsDFR, OsANS, and OsLAR), one modification gene (OsUGT), and one transport gene (OsGSTU34) were significantly upregulated, along with the activation of Rc, the key regulator of PA accumulation in the pericarp. Functional enrichment analysis of 56 differentially expressed genes specifically upregulated in RP rice at 28 DAF revealed the presence of three laccase genes known to cause the browning reaction through oxidation. These results expand our understanding of PA biosynthesis in rice, and provide a genetic basis that will lead to further studies on the genes and underlying molecular mechanisms associated with this process.

Health Benefits and Safety of Red Pigmented Rice (Oryza sativa L.): In Vitro, Cellular, and In Vivo Activities for Hair Growth Promoting Treatment

The hair growth-promoting activities of Thai native red (Sang-Yod-SY and Mun-Poo-MP) and black (Black glutinous-BG and Hom-Nil-HN) pigmented rice (Oryza sativa L.) extracts, including in vitro 5α-reductase inhibition, hair growth-promoting activity on human hair germinal matrix cells, and in vivo hair-cycle-converting activity in C3H/HeMlac mice, were investigated. Moreover, these extracts were determined to be safe via cytotoxicity (HaCaT cell) and in vivo irritation tests. The results showed that SY red rice extract with high contents of proanthocyanidin (1.50 ± 0.16 mgECE/g extract) exhibited significantly higher 5α-reductase inhibitory activity (18.5 ± 9.0 mgFEA/g extract) (p &lt; 0.05). The maximum growth-promoting activity for human matrix cells treated with SY extract reached about 216.2 ± 0.7% (1 mg/mL) relative to control (100%) after 3 days culture (p &lt; 0.05). Moreover, topical application of 1 mg/mL SY red pericarp rice extracts on shaven C3H skin in telogen phase led to significant hair regeneration (97.2 ±1.3%) based on the shaven area, while vehicle application only tended to yield a regeneration of 50.9 ± 11.7%. Red rice extracts were found to be safe, without signs of cytotoxicity and irritation. This research demonstrates the health benefits and safety of SY red pericarp extract when used for hair growing activity and its potential for use as a natural hair growth promoter and 5α-reductase inhibitor.

Identification of candidate genes and clarification of the maintenance of the green pericarp of weedy rice grains.

The weedy rice (Oryza sativa f. spontanea) pericarp has diverse colors (e.g., purple, red, light-red, and white). However, research on pericarp colors has focused on red and purple, but not green. Unlike many other common weedy rice resources, LM8 has a green pericarp at maturity. In this study, the coloration of the LM8 pericarp was evaluated at the cellular and genetic levels. First, an examination of their ultrastructure indicated that LM8 chloroplasts were normal regarding plastid development and they contained many plastoglobules from the early immature stage to maturity. Analyses of transcriptome profiles and differentially expressed genes revealed that most chlorophyll (Chl) degradation-related genes in LM8 were expressed at lower levels than Chl a/b cycle-related genes in mature pericarps, suggesting that the green LM8 pericarp was associated with inhibited Chl degradation in intact chloroplasts. Second, the F2 generation derived from a cross between LM8 (green pericarp) and SLG (white pericarp) had a pericarp color segregation ratio of 9:3:4 (green:brown:white). The bulked segregant analysis of the F2 populations resulted in the identification of 12 known genes in the chromosome 3 and 4 hotspot regions as candidate genes related to Chl metabolism in the rice pericarp. The RNA-seq and sqRT-PCR assays indicated that the expression of the Chl a/b cycle-related structural gene DVR (encoding divinyl reductase) was sharply up-regulated. Moreover, genes encoding magnesium-chelatase subunit D and the light-harvesting Chl a/b-binding protein were transcriptionally active in the fully ripened dry pericarp. Regarding the ethylene signal transduction pathway, the CTR (encoding an ethylene-responsive protein kinase) and ERF (encoding an ethylene-responsive factor) genes expression profiles were determined. The findings of this study highlight the regulatory roles of Chl biosynthesis- and degradation-related genes influencing Chl accumulation during the maturation of the LM8 pericarp.

Genome-Wide Association Study of Pericarp Color in Rice Using Different Germplasm and Phenotyping Methods Reveals Different Genetic Architectures.

Pericarp colors (PC) in rice are determined by the types and content of flavonoids in the pericarp. The flavonoid compounds have strong antioxidant activities and are beneficial to human health. However, the genetic basis of PC in rice is still not well-understood. In this study, a genome-wide association study (GWAS) of PC was performed in a diverse rice collection consisting of 442 accessions using different phenotyping methods in two locations over 2 years. In the whole population consisting of white and colored pericarp rice, a total of 11 quantitative trait loci (QTLs) were identified using two phenotyping methods. Among these QTLs, nine were identified using the phenotypes represented by the presence and absence of pigmentation in pericarp, while 10 were identified using phenotypes of the degree of PC (DPC), in which eight are common QTLs identified using the two phenotyping methods. Using colored rice accessions and phenotypes based on DPC, four QTLs were identified, and they were totally different from the QTLs identified using the whole population, suggesting the masking effects of major genes on minor genes. Compared with the previous studies, 10 out of the 15 QTLs are first reported in this study. Based on the differential expression analysis of the predicted genes within the QTL region by both RNA-seq and real-time PCR (RT-PCR) and the gene functions in previous studies, LOC_Os01g49830, encoding a RAV transcription factor was considered as the candidate gene underlying qPC-1, a novel QTL with a large effect in this study. Our results provide a new insight into the genetic basis of PC in rice and contribute to developing the value-added rice with optimized flavonoid content through molecular breeding.

Identification of genomic loci governing pericarp colour through GWAS in rice (Oryza sativa L.)

Rice pericarp colour is one of the nutritional traits that is now gaining attention worldwide. In the present investigation, genome-wide association GWAS) was performed to identify loci governing pericarp colour in rice. A set of 1,349,269 SNPs and precise phenotyping across 325 diverse accessions of rice were used for the GWAS. The accessions belong to five rice isozyme classification groups viz., indica, japonica, aromatic, aus, and admix. The GWAS identified two significant loci gPC5-1and gPC7-1 on chromosomes, 5 and 7, respectively, associated with the pericarp colour in rice. The SNPs on chromosome 7 co-localized with the functionally characterized Os07g0211500 (Rc gene) known to control pericarp colour and Os07g0214900 which is similar to the Chalcone synthase 2(OsCHS2) gene involved in flavonoid synthesis pathway. Linkage disequilibrium analysis across 0.25 Mbp upstream and downstream of these markers suggested three strong linkage blocks on chromosome 7. More interestingly, the novel locus identified on chromosome 5 gPC5-1 does not harbor any homolog of previously reported genes. Therefore, the locus can serve as a basis for identifying a new gene for rice pericarp colour. The results presented here will be helpful to understand the genetic regulation of pericarp colour and for genomic-assisted breeding in rice.

Red rice drying and storage: Effects on technological properties and phenolic compounds of the raw and cooked grains

The use of pigmented rice grains has increased in the food industry in recent years, however, the effects of post-harvest on chemical, physical and technological properties are poorly known. Pigmented rice grains were dried at temperatures between 40 and 100 °C, followed by storage for 12 months, to evaluate the technological properties and phenolic compounds of rice grains with red pericarp. The increase in drying temperature promoted reductions in head rice yield (HRY), soluble protein, cooking time, grain integrity after cooking, total free and bound phenolics, and total proanthocyanidins and increased electrical conductivity, defects, hardness, and rehydration index. The prolonged storage of grains dried at temperatures above 60 °C promoted an increase in electrical conductivity, defects, hardness and reduction of soluble protein, cooking time, and total free phenolics, possibly due to the formation of cracks in the grains and due to latent damage in grain storage. Therefore, it is recommended drying temperatures below 60 °C for the storage of red pericarp rice grains for adequate conditions of conservation of technological properties and phenolic compounds.

An OsKala3, R2R3 MYB TF, Is a Common Key Player for Black Rice Pericarp as Main Partner of an OsKala4, bHLH TF.

Rice (Oryza sativa) pericarp exhibits various colors due to the accumulation of anthocyanins and/or proanthocyanidins. Previous work revealed that the two basic helix-loop-helix (bHLH) transcription factors OsKala4 and OsRc are key regulators for the black and red pericarp traits, respectively, and their inactivation results in rice with white pericarp. However, their pericarp-specific R2R3 MYB partner remained unknown. Here, we characterized the role of the R2R3 MYB gene OsKala3 in rice pericarp pigmentation through genetic and molecular approaches. A rice protoplast transfection assay showed that OsKala3 is a nuclear-localized protein. Furthermore, OsKala3 physically interacted with OsKala4 in a yeast two-hybrid analysis. Co-transfection assays in rice protoplasts revealed that OsKala3 and OsKala4 mediate the activation of anthocyanin biosynthetic genes. Notably, the OsKala3 promoter region exhibited an insertion polymorphism specifically in rice cultivars with black pericarp, creating two tandem repeats while red and white varieties harbor only one. The number of repeats within the OsKala3 promoter correlated with increased transactivation by OsKala3, thus providing a rationale for the black pericarp characteristic of cultivars with two repeats. These results thus provide evidence for the molecular basis of anthocyanin biosynthesis in rice pericarp and may facilitate the introduction of this beneficial trait to other rice cultivars through marker-assisted breeding.

Application of Cyanidin-3-Glucosides as a functional food ingredient in rice-based bakery products.

BackgroundBlack pericarp rice has recently become popular among rice consumers for its diverse health benefits specially anti-cancer effect. Cyanidin-3-Glucosides (C3G), an prominant bioactive component of anthocyanins which is abundantly present in black pericarp rice.ObjectivesWe investigated, how effectively it can be used to fortify Cyanidin-3-Glucosides (C3G) content in red and white pericarp polished rice or rice based bakery products for more nutritional value.MethodIn the present study, we have characterized several black pericarp rice cultivars along with some red pericarp and white pericarp rice cultivars by physicochemical including mineral profiling, and quantified the C3G by UFLC and LCMS.ResultsC3G content was significantly reduced from raw rice to cooked rice condition. All the black pericarp rice cultivars synthesized C3G, while this content was not detected in red and white pericarp rice cultivars. However, when 25% of black pericarp rice were mixed with 75% red or white pericarp polished rice, C3G content was significantly retained in cooked rice conditions. Formulation of rice-based bakery food product using black pericarp rice powder was also remarkably retained the C3G content as compared to that of cooking. Black rice is harder in texture, difficult to digest and needs higher energy for cooking. Therefore, we tried to circumvent these challenges by fortifying 25% of black pericarp rice with white or red pericarp rice.ConclusionFortification of C3G enriched black rice (25%) with red or white pericarp rice (75%) might bring a better nutritional quality in both cooking and baking condition. This may lead a way to the effective management of the non-communicable disease such as cancer for common rice consuming population.

Genetic analysis and molecular mapping of Rp, a mutant gene encoding red pericarp in rice (Oryza sativa L.)

Coloured rice has pigments deposited in the grain pericarp; red rice is the most common type of coloured rice. Red rice is rich in essential nutrients and has been grown and consumed in China for a long time. In this study, we report the genetic characterisation and preliminary molecular mapping of a mutant gene encoding red pericarp in rice (Oryza sativa L.). To analyse the genetic basis of the red pericarp mutant, a reciprocal cross between GER-3 (red pericarp, indica cv.) and 898 (white pericarp, indica cv.) was made. The genetic analysis results confirmed that there was only one dominant gene, temporarily designated Rp (Red pericarp) controlling the segregation of the red pericarp in the F&lt;sub&gt;2&lt;/sub&gt; population. For the molecular mapping of Rp, an F&lt;sub&gt;2&lt;/sub&gt; population derived from an inter-subspecific cross between Gene Engineering Rice-3 (GER-3) and C418 (japonica cv., white pericarp) was constructed. The genotype of the pericarp colour of the F&lt;sub&gt;2&lt;/sub&gt; individuals in the mapping population was validated by progeny testing of the F&lt;sub&gt;2:3&lt;/sub&gt; families. Simple sequence repeat (SSR) markers and the bulked segregation analysis (BSA) method were used; Rp was mapped to the short arm of chromosome 7 between the SSR markers RM21182 and RM21268, with a genetic distance of 3.5 and 12.0 cM, respectively. In this paper, the potential origin of the red pericarp mutant gene Rp was also discussed.

Transcription Factors Rc and OsVP1 Coordinately Regulate Preharvest Sprouting Tolerance in Red Pericarp Rice.

Red pericarp associates with seed dormancy or preharvest sprouting (PHS) tolerance in crops. To identify this association's molecular mechanism, a PHS mutant Osviviparous1 (Osvp1) was characterized in rice and crossed with Kasalath, a red pericarp cultivar with Rc (red coleoptiles) genotype. Among the dehulled seeds of F2 progenies, RcRcvp1vp1 seeds performed a lower PHS rate than rcrcvp1vp1 seeds and showed shallower pigmentation than RcRcVP1VP1 seeds. Kasalath and SL9 (an RcRcVP1VP1 substitution line with Nipponbare background) showed more ABA sensitivity than the Nipponbare (rcrcVP1VP1) by the germination assay, and the transcriptional abundance of ABA signal genes OsABI2, OsSnRK2, OsVP1, ABI5, and especially OsVP1 increased in the red pericarp line SL9. Moreover, OsVP1 can directly bind Rc (bHLH) promoter by yeast one-hybrid, which activates Rc and OsLAR expression in red pericarp rice. Furthermore, a luciferase complementation imaging assay showed that OsVP1 interacts with transcriptions factors Rc and OsC1. These results indicate that OsVP1 promotes proanthocyanidin accumulation through the interaction among OsVP1, Rc, and OsC1 and then increases the plant's ABA sensitivity and PHS resistance.

Physical Properties and Glycemic Index of Organic and Conventional Black Rice Grown in Bali Indonesia

Similar variety of black rice was grown by organic and conventional methods in Jatiluweh and Penatih districts of West Bali, respectively, separated by 46 km distance. Both rice are very similar having black pericarp and white rice inside. In this study we found that the degree of crystallinity of the two rice is about 24%. The Bragg parameters of the conventional rice are very close to α-amylose dehydrate, whereas the organic rice exists in polymorphic form. The crystallites in the endosperm area are dominated by polyhedral shape in contact with each other at the edges and formed a cyclic geometric environment. The size of the crystallites was between three and six microns. On the whole the crystallites are packed in rectangular blocks connected with one another radially from the centre towards the pericarp. XRF experiments show both rice contain P, K, S, Si, Mg, Cl, Al, Zn, Fe, Cu and Rb. However, ruthenium and manganese were detected in the organic rice. Both organic and conventional black rice possess low glycemic index of about 31±5.0 compared to 50±5.8 for commercial Basmati rice. Thermogravimetric investigation showed that the black rice was stable up to about 300°C and the gradual mass loss between 80 and 210°C is due to water molecules and additional components presence in the rice. After the major decomposition at 310°C the mass gradually decreased and reached 18% residual at 600°C.

Weedy Rice as a Novel Gene Resource: A Genome-Wide Association Study of Anthocyanin Biosynthesis and an Evaluation of Nutritional Quality.

The pericarp color of rice grains is an important agronomic trait affected by domestication, and the color pigment, anthocyanin, is one of the key determinants of rice nutritional quality. Weedy rice, also called red rice because its pericarp is often red, may be a novel gene resource for the development of new rice. However, the genetic basis and nutritional quality of anthocyanin are poorly known. In this study, we used a genome-wide association study (GWAS) to find novel and specific QTLs of red pericarp in weedy rice. The known key gene site of red pericarp Rc was detected as the common genetic basis of both weedy and cultivated rice, and another 13 associated signals of pericarp color that were identified may contribute specifically to weedy rice pericarp color. We then nominated three pericarp color genes that may contribute to weedy rice divergence from cultivated rice based on selection sweep analysis. After clarifying the distribution and growth dynamics of pigment in weedy rice caryopsis, we compared its nutritional quality with cultivated rice. We found that sampled weedy rice pericarps had much greater quantities of anthocyanin, beneficial trace elements, free amino acids, and unsaturated fatty acids than the cultivated rice. In conclusion, the gene resources and novel genetic systems of rice anthocyanin biosynthesis explored in this study are of great value for the development of nutritious, high anthocyanin content rice.

BRS 901 and BRS 902: red rice cultivars bred for Brazil

Abstract BRS 901 and BRS 902 are red pericarp rice cultivars developed by Embrapa for irrigated and rainfed lowland production systems in Brazil. These cultivars have medium and early maturation cycles, respectively, and both have high grain yield potential, good lodging tolerance and short to medium length grains.

Mapping and Identifying a Candidate Gene Plr4, a Recessive Gene Regulating Purple Leaf in Rice, by Using Bulked Segregant and Transcriptome Analysis with Next-Generation Sequencing.

The anthocyanin biosynthesis of rice is a major concern due to the potential nutritional value. Purple appears in various organs and tissues of rice such as pericarp, flower organs, leaves, leaf sheaths, internodes, ligules, apex, and stigma. At present, there are many studies on the color of rice pericarp, but the gene and mechanism of other organs such as leaves are still unclear, and the gene regulatory network of specific organ coloring has not been systematically understood. In this study, genetic analysis demonstrated that the purple leaf traits of rice were regulated by a recessive gene. The green leaf cultivar Y58S and purple leaf cultivar XianHongB were used to construct the mapping population. A set of near isogenicline (NIL) (BC3F1) was bred via crossing and back-crossing. The generations of BC3F2 appeared to separate four phenotypes, pl1, pl2, pl3, and pl4, due to the occurrence of a purple color in different organs. We constructed three bulked segregant analysis (BSA) pools (pl1–pl2, pl1–pl3, and pl1–pl4) by using the separated generations of BC3F5 and mapped the purple leaf gene plr4 to the vicinity of 27.9–31.1 Mb on chromosome 4. Subsequently, transcriptome sequencing (RNA-Seq) for pl3 and pl2 was used to analyze the differentially expressed genes in the localization interval, where 12 unigenes exhibited differential expression in which two genes (Os04g0577800, Os04g0616400) were downregulated. The two downregulated genes (Os04g0577800 and Os04g0616400) are possible candidate genes because of the recessive genetic characteristics of the purple leaf genes. These results will facilitate the cloning of plr4 and illustrate the molecular mechanisms of the anthocyanin synthesis pathway.

GENETICS OF THE TRAITS IN THE RICE HYBRID ‘SVETLY X MAVR

Rice can form not only white, but also red, brown and black kernels. In black rice pericarp contains anthocyanin pigment, which has antioxidant activity and is beneficial to human health. The article is devoted to the development of new rice lines with black pericarp on the basis of the hybrid ‘Svetly × Mavr’. The purpose of the work is to develop rice new lines with black seed vessel on the genetic background of the variety ‘Svetly’. There has been carried out a genetic analysis of varying quantitative traits that affect rice productivity. Cleavage by pericarp color occurred according to the dihybrid scheme according to the type of recessive epistasis in the ratio 9:3:4. The black color of the pericarp was formed with the presence of two dominant Pb and Pp genes in the genotype, the brown one was determined by the Pb gene, and the white one was determined by the other combinations of genes. Inheritance of plant height occurred according to the overdominance of large values of the trait. Parental forms differed in the allelic state of two pairs of genes. Along the panicle length, there has been determined partial negative dominance and monogenic differences of the hybridized varieties. According to ‘number of spikelets per panicle’, there has been identified an overdominance of a larger value of the trait and the interaction of two pairs of genes. According to ‘1000-kernel weight’, there has been established partial dominance of large values of the trait and monogenic differences of the initial parental forms. There have been selected the best recombinant forms combining a compact erect panicle and grains with a black seed vessel, and there has been developed starting material for practical breeding. The study was carried out on the fields of the Experimental Station “Proletarskaya” of the Rostov Region in 2018.

CRISPR/Cas9-mediated functional recovery of the recessive rc allele to develop red rice.

SummaryRed rice contains high levels of proanthocyanidins and anthocyanins, which have been recognized as health‐promoting nutrients. The red coloration of rice grains is controlled by two complementary genes, Rc and Rd. The RcRd genotype produces red pericarp in wild species Oryza rufipogon, whereas most cultivated rice varieties produce white grains resulted from a 14‐bp frame‐shift deletion in the seventh exon of the Rc gene. In the present study, we developed a CRISPR/Cas9‐mediated method to functionally restore the recessive rc allele through reverting the 14‐bp frame‐shift deletion to in‐frame mutations in which the deletions were in multiples of three bases, and successfully converted three elite white pericarp rice varieties into red ones. Rice seeds from T1 in‐frame Rc lines were measured for proanthocyanidins and anthocyanidins, and high accumulation levels of proanthocyanidins and anthocyanidins were observed in red grains from the mutants. Moreover, there was no significant difference between wild‐type and in‐frame Rc mutants in major agronomic traits, indicating that restoration of Rc function had no negative effect on important agronomic traits in rice. Given that most white pericarp rice varieties are resulted from the 14‐bp deletion in Rc, it is conceivable that our method could be applied to most white pericarp rice varieties and would greatly accelerate the breeding of new red rice varieties with elite agronomic traits. In addition, our study demonstrates an effective approach to restore recessive frame‐shift alleles for crop improvement.

Characteristics of Flour and Starch Isolated from Red Rice Subjected to Different Drying Conditions

Drying is a method used to reduce grain moisture and prolong safe storage. The objective of the study is to evaluate the changes in red rice flour and starch submitted to sun‐drying, continuous drying at 40 °C, continuous drying at 100 °C and intermittent drying. In general, the significant changes are found in continuous drying at 100 °C, followed by intermittent drying, continuous drying at 40 °C and sun‐drying. Continuous drying at 100 °C reduces starch extraction yield and increases residual protein, leading to starch with dark reddish stains. At higher temperatures, increases in TO and relative crystallinity and lower solubility, swelling power, ΔT occur. The flour gel presents higher values when intermittent drying is applied, differing from the starch gel, which higher hardness found at continuous drying method at 40 °C probably due to the macromolecules from rice pericarp. According to the increase in grain drying temperature, there are reductions in final viscosity and setback in the starch and increases in final viscosity and setback in the flour, attributed mainly to the high amount of protein. The parameters of RVA and texture demonstrates that the higher purity of the starch promotes a gel with greater stability in refrigeration.