Non-aromatic Rice Varieties Research Articles

Genetic analysis of quality traits in non-aromatic rice varieties for export potential

Genetic analysis of quality traits in non-aromatic rice varieties for export potential

Identification of Key Volatiles Differentiating Aromatic Rice Cultivars Using an Untargeted Metabolomics Approach.

Non-aromatic rice is often sold at the price of aromatic rice to increase profits, seriously impairing consumer experience and brand credibility. The assessment of rice varieties origins in terms of their aroma traits is of great interest to protect consumers from fraud. To address this issue, the study identified differentially abundant metabolites between non-aromatic rice varieties and each of the three most popular aromatic rice varieties in the market using an untargeted metabolomics approach. The 656 metabolites of five rice grain varieties were determined by headspace solid-phase extraction gas chromatography-mass spectrometry, and the multivariate analyses were used to identify differences in metabolites among rice varieties. The metabolites most differentially abundant between Daohuaxiang 2 and non-aromatic rice included 2-acetyl-1-pyrroline and acetoin; the metabolites most differentially abundant between Meixiangzhan 2 and non-aromatic rice included acetoin and 2-methyloctylbenzene,; and the metabolites most differentially abundant between Yexiangyoulisi and non-aromatic rice included bicyclo[4.4.0]dec,1-ene-2-isopropyl-5-methyl-9-methylene and 2-methylfuran. Overall, acetoin was the metabolite that was most differentially abundant between the aromatic and non-aromatic rice. This study provides direct evidence of the outstanding advantages of aromatic rice and acts a reference for future rice authentication processes in the marketplace.

Creation of novel alleles of fragrance gene OsBADH2 in rice through CRISPR/Cas9 mediated gene editing.

Fragrance in rice grains is a key quality trait determining its acceptability and marketability. Intensive research on rice aroma identified mutations in betaine aldehyde dehydrogenase (OsBADH2) leading to production of aroma in rice. Gene editing technologies like CRISPR/Cas9 system has opened new avenues for accelerated improvement of rice grain quality through targeted mutagenesis. In this study, we have employed CRISPR/Cas9 tool to create novel alleles of OsBADH2 leading to introduction of aroma into an elite non-aromatic rice variety ASD16. PCR analysis of putative transformants using primers targeting the flanking regions of sgRNA in the 7th exon of OsBADH2 identified 37.5% potential multi-allelic mutations in T0 generation. Sensory evaluation test in the leaves of T0 lines identified thirteen lines belonging to five independent events producing aroma. Sequence analysis of these aromatic T0 lines identified 22 different types of mutations located within -17 bp to +15bp of sgRNA region. The -1/-2 bp deletion in the line # 8-19 and -8/-5 bp deletion in the line # 2-16 produced strong aroma and the phenotype was stably inherited in the T1 generation. Comparative volatile profiling detected novel aromatic compounds viz., pyrrolidine, pyridine, pyrazine, pyradazine and pyrozole in the grains of T1 progenies of line # 8-19. This study has demonstrated the use of CRISPR/Cas9 in creating novel alleles of OsBADH2 to introduce aroma into any non-aromatic rice varieties.

Characterization of Haplotype Diversity in the BADH2 Aroma Gene and Development of a KASP SNP Assay for Predicting Aroma in U.S. Rice

BackgroundAroma is an important grain quality trait in rice, controlled by mutations within the BADH2 gene. The trait is simply inherited, and its importance in variety development makes it a practical target for marker-assisted selection in applied breeding programs. The predominant functional mutation within BADH2, an 8-bp indel, can be reliably detected using a PCR-based assay, but the available assays and associated genotyping platforms are insufficient for large-scale applied molecular breeding applications and are not compatible with outsourcing genotyping services.ResultsWe first characterized SNP diversity across the BADH2 gene in a collection of 2932 rice varieties to determine the number of gene haplotypes in O. sativa. Using 297 gene-based SNPs, 11 haplotype groups were detected, and subsequently identified a minimal set of nine informative SNPs that uniquely identified the BADH2 haplotypes. These nine SNPs were developed into KASP assays and used to examine a panel of 369 U.S. rice accessions. The panel represented modern breeding germplasm and included all known aroma pedigree sources in U.S. rice. Six haplotypes were detected within the U.S. panel, of which two were found in majority (85%) of varieties. A representative set of 39 varieties from all haplotype groups was evaluated phenotypically to distinguish aromatic from non-aromatic lines.ConclusionOne haplotype (Hap 6) was found to be perfectly associated with the aromatic phenotype. A single KASP SNP unique to Hap 6 was demonstrated to reliably differentiate aromatic from non-aromatic rice varieties across U.S. germplasm.

Key-Marker Volatile Compounds in Aromatic Rice (Oryza sativa) Grains: An HS-SPME Extraction Method Combined with GC×GC-TOFMS.

The aroma of rice essentially contributes to the quality of rice grains. For some varieties, their aroma properties really drive consumer preferences. In this paper, using a dynamic headspace solid-phase microextraction (HS-SPME) system coupled to a two-dimensional gas chromatography (GC×GC) using a time-of-flight mass spectrometric detector (TOFMS) and multivariate analysis, the volatile compounds of aromatic and non-aromatic rice grains were contrasted to define some chemical markers. Fifty-one volatile compounds were selected for principal component analysis resulting in eight key-marker volatile compounds (i.e., pentanal, hexanal, 2-pentyl-furan, 2,4-nonadienal, pyridine, 1-octen-3-ol and (E)-2-octenal) as responsible for the differences between aromatic and non-aromatic rice varieties. The factors that are most likely to affect the HS-SPME efficiency for the aforementioned key-marker compounds were evaluated using a fractional factorial design in conjunction with multi-response optimisation. The method precision values, expressed as % of coefficient of variation (CV), were ranging from 1.91% to 26.90% for repeatability (n = 9) and 7.32% to 37.36% for intermediate precision (n = 3 × 3). Furthermore, the method was successfully applied to evaluate the volatile compounds of rice varieties from some Asian countries.

Evaluating Non-Aromatic Rice Varieties for Growth and Yield under Different Rates of Soil Applied Boron

Balanced boron (B) fertilization has prime importance to obtain maximum paddy yield. The range between B deficiency and toxicity is smaller than most plant nutrients, though B requirement among different crops varies widely. The adequate dose of B for one genotype can either be insufficient or toxic to other. Hence, without knowing the actual requirements of crop varieties, B application can be risky due to the toxicity hazards. A field experiment was undertaken at experimental farm of Nuclear Institute of Agriculture (NIA), Tandojam during 2013, to evaluate the B requirement of two non-aromatic rice varieties. The experiment was arranged in split plot design with three repeats. Two rice varieties Sarshar and Shandar were grown in main plots with four rates of B: 0.5, 1.0, 1.5 and 2.0 kg ha-1 and control (0 kg ha-1) in sub plots. Both the varieties responded differently to B rates. Sarshar produced the highest paddy yield (5691 kg ha-1) at a rate of 1.5 kg B ha-1 and was 18% greater than control, Shandar produced the highest yield (6075 kg ha-1) at a rate of 1.0 kg B ha-1and was 5% greater than control. B accumulation in paddy and straw of both varieties increased with the increasing B rates. Both varieties were also significantly (p<0.05) varied in B accumulations. Comparatively, rice variety Sarshar accumulated 9% and 22% more B in straw and paddy than the Shandar. Thus, the B requirement of Sarshar was relatively higher than the Shandar. Shandar can be grown without the additional B application, whereas, Sarshar requires additional B for its maximum harvest in B deficient soils.

Understanding the Fragrance in Rice

Aroma in plants is a result of numerous volatile and semi volatile compounds present within Fragrance in grain rice is the most attractive trait that provides a premium price in the market. Continuously increasing demand for fragrant rice in global market gained a special attraction of rice breeders and forced them for considering rice grain aroma among major objectives for commercially improved rice varieties. Since, aromatic varieties are very rare these may be considered among most precious treasure of India and can also be considered as national asset and pride. The fragrance of rice plays an important role in affecting the market value and consumers’ preference [1-3]. These characteristic aromatic rice have been reported in three different genetic sub populations of rice viz. Group V (Sadri and Basmati), indica (Jasmine), and tropical japonica [4] of more than 250 volatile and non-volatile compounds reported in both fragrant and nonfragrant rice varieties, a novel compound namely 2-acetyl-pyrrolin (2AP) has been significantly found as primary contributor in imparting the unique pop-corn like aroma in rice [5-8]. It has been reported that both aromatic and non-aromatic rice varieties have the characteristic aroma compound 2AP and the only difference lies in concentration between them [9]. In a comparative study, compounds alkanals, alk-2-enals, alka(E)-2,4-dienals, 2-pentylfuran, 2-acetyl-1-pyrroline and 2-phenylethanol have been reported as major contributors in total aroma profiling of rice. Besides, 2-acetyl-1-pyrroline and other previously known aroma imparting volatile compounds, recently few more novel compounds viz. 2-amino acetophenone and 3-hydroxy- 4,5-dimethyl-2(5H)-furanone (found in high levels in Basmati 370) [10], and guaiacol, indole and p-xylene in Black rice [11], were found to be mainly responsible for its unique flavour. The strength of aroma greatly depends upon the concentration of 2AP in rice grain tissues, however the odour threshold level of rice is 0.1 ppb, its range of concentration in aromatic rice varieties varies from 6 ppb to 90 ppb for the milled rice and 100 ppb to 200 ppb in brown rice, depending upon the variety such as in Basmati rice (0.34 ppm), Jasmine rice (0.81 ppm) and Texmati (0.53 ppm).

Effects of High-Quality Aromatic Rice Varieties on the Fitness of the Striped Stem Borer, Chilo suppressalis (Walker) in Central China

The striped stem borer (SSB), Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), is a major pest of rice in China. Variation in host-plant quality may affect the body size of herbivorous insects, which in turn, can determine their life-history parameters such as survival, fecundity and fitness. In this study, we tested the effects of high-quality aromatic rice varieties on the fitness of SSB in China. Results showed that 1st instar larvae had higher penetrating rates and survival rates on the high-quality aromatic rice varieties (EX-1 and WX-988) than that on the non-aromatic rice varieties (EZ-5 and LYP-9). In addition, shorter developmental periods, greater female pupal weights and higher of other life-history parameters (hatching rate, pupation rate, eclosion rate and increase index) were found on the high-quality aromatic rice varieties, although only female pupal weight showed a significant difference between the two varieties. The highest dead heart rate was found on the aromatic rice variety of EX-1. These results indicate that SSB sustains a lower fitness cost when consuming the high-quality aromatic rice varieties (EX-1 and WX-988) than on the non-aromatic rice varieties (EZ-5 and LYP-9) in Central China.

Chemical Constituents and Post-Harvest Prospects of Pandanus amaryllifolius Leaves: A Review

The leaves of Pandanus amaryllifolius Roxb. are widely used for flavoring food items. Extensive work has been done on agro parameters and propagation techniques as well as isolation and identification of the important chemical constituents such as volatile compounds, proteins, alkaloids and flavonoids. This review focuses on the possibilities of using the leaves in food and nonfood industries with particular reference to its aroma component. The major aromatic compound, 2-acetyl-1-pyrroline, has commercial significance as a flavor constituent that imparts the characteristic aroma of scented rice varieties such as basmati rice in India and in several Asian rice varieties. The compound can be added to nonaromatic rice varieties and other food formulations. The location and concentration of 2-acetyl-1-pyrroline in both Pandanus amaryllifolius and aromatic rice has been studied, as has the feasibility of extraction of 2-acetyl-1-pyrroline using different methodologies. The different methods for processing and preservation of this flavor compound are reviewed as are the application potential for flavor enrichment. Further, the therapeutic value of Pandanus amaryllifolius leaves and their importance in other areas as a source of phytochemicals and insecticide has also been documented.

Genetic diversity in grain quality and nutrition of aromatic rices

The study was conducted at Bangladesh Rice Research Institute (BRRI), Gazipur in 2005 to assess the genetic divergence of aromatic rices for grain quality and nutrition aspects. Forty genotypes composed of 32 local aromatic, five exotic aromatic and three non-aromatic rice varieties were used. Univariate and multivariate analyses were done. Enormous variations were observed in majority of characters viz. grain length, breadth, kernel weight, milling yield, kernel length, L/B ratio of kernel, volume expansion ratio (VER), protein content, amylose content, elongation ratio (ER) and cooking time. In multivariate analysis, genotypes were grouped into six clusters. In the discriminant function analysis (DFA), function 1 alone absorbed 61.7% of the total variance. The most contributing variables were kernel weight, kernel length and L/B ratio in function 1. The inter-cluster D2 value was maximum (26.53) between I and VI followed by 21.28 (between I and V). Minimum D2 value was found (5.90) between II and III. Majority of the local aromatic rice varieties with smaller kernels were included in the cluster I. The cluster III contains Elai, sarwati and sugandha-1 with long-slender kernel and ‘very good’ appearance. Thus, these varieties can be used in breeding programme for improvement of germplasms in cluster-I.

Characterization of the major fragance gene from an aromatic japonica rice and analysis of its diversity in Asian cultivated rice

In Asian cultivated rice (Oryza sativa L.), aroma is one of the most valuable traits in grain quality and 2-ACP is the main volatile compound contributing to the characteristic popcorn-like odour of aromatic rices. Although the major locus for grain fragrance (frg gene) has been described recently in Basmati rice, this gene has not been characterised in true japonica varieties and molecular information available on the genetic diversity and evolutionary origin of this gene among the different varieties is still limited. Here we report on characterisation of the frg gene in the Azucena variety, one of the few aromatic japonica cultivars. We used a RIL population from a cross between Azucena and IR64, a non-aromatic indica, the reference genomic sequence of Nipponbare (japonica) and 93–11 (indica) as well as an Azucena BAC library, to identify the major fragance gene in Azucena. We thus identified a betaine aldehyde dehydrogenase gene, badh2, as the candidate locus responsible for aroma, which presented exactly the same mutation as that identified in Basmati and Jasmine-like rices. Comparative genomic analyses showed very high sequence conservation between Azucena and Nipponbare BADH2, and a MITE was identified in the promotor region of the BADH2 allele in 93–11. The badh2 mutation and MITE were surveyed in a representative rice collection, including traditional aromatic and non-aromatic rice varieties, and strongly suggested a monophylogenetic origin of this badh2 mutation in Asian cultivated rices. Altogether these new data are discussed here in the light of current hypotheses on the origin of rice genetic diversity.

Aroma enrichment and the change during storage of non-aromatic milled rice coated with extracted natural flavor

Three non-aromatic rice varieties (RD23, SPR1 and SPR90) were coated in a modified spouted bed with 30% sorbitol-plasticized rice-starch film containing 25% pandan ( Pandanus amaryllifolius Roxb.) leaf extract produced by the supercritical fluid with carbon dioxide extraction method. The coated and uncoated samples and uncoated aromatic rice (KDML and PTT1 varieties) were packed in plastic bags (nylon15/PE20/LLDPE75) and stored at 25 °C for 6 months. Gas chromatography–mass spectrometry analysis revealed that the coating treatment resulted to similar flavor volatile profile as that of aromatic varieties, particularly the presence of 2-acetyl-1-pyrroline (ACPY) which is the main volatile compound responsible for the jasmine aroma. ACPY was absent in uncoated non-aromatic rice and ACPY content of non-aromatic rice coated with natural pandan extract was lower than that of uncoated aromatic rice. During storage, ACPY levels decreased. Coated non-aromatic rice retained higher ACPY levels than the aromatic PTT1 variety. The coating treatment also reduced the n-hexanal content of stored grains. Thus, the coating technique is a promising approach for rice aroma improvement and at the same time, for reducing the potential for oxidative rancidity during grain storage.

RAPD Analysis of Aromatic and Non-aromatic Rice (Oryza sativa L.)

Genetic variation in nine aromatic and four nonaromatic rice varieties (Oryza sativa L.) was investigated at the DNA level using the randomly amplified polymorphic DNA (RAPD) technique. Twenty six random primers were used to amplify DNA segments and 177 PCR products were obtained of which 98 were polymorphic. One primer did not show polymorphism. A dendrogram showing the genetic distances of 13 rice varieties was constructed based on RAPD data.