Fragrance Gene Research Articles

Molecular genetic analysis of strawberry genotypes for the FaOMT fruit aroma gene

The results of the analysis of allelic polymorphism of strawberry varieties and forms for the FAOMT fruit aroma gene were shown. The non-functional allele FaOMT- in the homozygous state was detected in strawberry variety Quicky. Heterozygous genotype (FaOMT+FaOMT-) was identified in the strawberry varieties Feyerverk, Ostara, Polka and Symphony, and selected forms 26-5 and 928-12. The functional allele FaOMT gene (FaOMT+) in the homozygous state (FaOMT+FaOMT+ genotype) was detected in strawberry varieties Borovitskaya, Kubata, Troitskaya, Tsaritsa, Yarkaya, Korona and Vima Kimberly, and selected forms 932-29 and 298-19-9-43, which allows us to be used as valuable initial forms in breeding for fruit aroma.

New fragrance allele according to insertion/deletion in non-coding DNA sequence of the Fragrance gene found in Asian cultivated rice (Oryza sativa L.), wild and weedy relatives from Indochina

New fragrance allele according to insertion/deletion in non-coding DNA sequence of the Fragrance gene found in Asian cultivated rice (Oryza sativa L.), wild and weedy relatives from Indochina

Network analysis reveals the co-expression of sugar and aroma genes in the Chinese white pear (Pyrus bretschneideri)

The quality of pear and other fruit affects their economic value by determining their attractiveness to the consumer. For this reason the two most important quality traits, namely the sugar content and the aroma, have been the focus of much research. This research has been conducted both on the biochemical characteristics of sugar and aroma of fruits and on the activity of enzymes related to their metabolism. In this study, by analyzing the transcriptome of pear fruit, we built the first co-expression network of the genes related to sugar metabolism and those related to aroma, to reveal their connections. Genes that encode beta-glucosidases and sorbitol dehydrogenases are shown to be the hub genes within this network. This study has demonstrated the power of such network analysis for the first time in a non-model organism. Our research can lead to new discoveries that go beyond the previous focus on individual genes.

Studies on Aroma Gene and its Application in Rice Genetics and Breeding

Rice (Oryza sativa L.) is one of the most important food crops in the world, and the staple food for more than half of the world’s population. Along with the sustained development of living standards, people’s demand for high quality rice is increasing. As one of the types of cultivated rice, aromaticrice is preferred by most of the consumers because of its agreeable scent. With the rapid development of rice functional genomics and sequencing technology, great progress has been made in understanding the aroma gene in rice, and a series of functional markers has been developed for screening the aroma gene and breeding new rice varieties in recent years. This paper mainly reviews the progress in the genetic basis, gene function and regulation of the aroma gene, and the application of aroma gene functional markers in the genetic improvement and breeding of aromaticrice. Thus, it provides important references for the cultivation of new varieties of aromaticrice.

Whole genome sequencing of Oryza sativa L. cv. Seeragasamba identifies a new fragrance allele in rice.

Fragrance of rice is an important trait that confers a large economic benefit to the farmers who cultivate aromatic rice varieties. Several aromatic rice varieties have limited geographic distribution, and are endowed with variety-specific unique fragrances. BADH2 was identified as a fragrance gene in 2005, and it is essential to identify the fragrance alleles from diverse geographical locations and genetic backgrounds. Seeragasamba is a short-grain aromatic rice variety of the indica type, which is cultivated in a limited area in India. Whole genome sequencing of this variety identified a new badh2 allele (badh2-p) with an 8 bp insertion in the promoter region of the BADH2 gene. When the whole genome sequences of 76 aromatic varieties in the 3000 rice genome project were analyzed, the badh2-p allele was present in 13 varieties (approximately 17%) of both indica and japonica types. In addition, the badh2-p allele was present in 17 varieties that already had the loss-of-function allele, badh2-E7. Taken together, the frequency of badh2-p allele (approximately 40%) was found to be greater than that of the badh2-E7 allele (approximately 34%) among the aromatic rice varieties. Therefore, it is suggested to include badh2-p as a predominant allele when screening for fragrance alleles in aromatic rice varieties.

Rapid and targeted introgression of fgr gene through marker-assisted backcrossing in rice (Oryza sativa L.).

While it is crucial for developing countries like Malaysia to achieve self-sufficiency in rice (Oryza sativa L.), it is equally critical to be able to produce high-quality rice, specifically fragrant rice, which demands are often met through importation. The present study was aimed at developing high-yielding fragrant rice, in a timely and cost-effective manner. A marker-assisted backcross (MABC) approach was optimised to introgress the fragrance gene (fgr) into two high-yielding Malaysian varieties, MR84 and MR219, within two years utilising less than 50 molecular markers. Coupled with phenotypic screening, one single foreground marker (fgr-SNP) and 48 background markers were selected and utilised, revealing recovery of at least 90% of recurrent parent genome (RPG) in merely two backcross generations. Collectively, the yield potential of the developed BC2F2 lines (BLs) was higher (P > 0.05) than the donor parent, MRQ74, and similar (P < 0.05) to both the recurrent parents, MR84 and MR219. In addition, some of the developed BLs showed good grain quality, such as having long grain. We believe that this is the first report comprising the validation and utilisation of the single functional marker system (fgr-SNP) in introgressing the fgr gene into different rice varieties.

English

English

Abscisic acid, sucrose, and auxin coordinately regulate berry ripening process of the Fujiminori grape

The aim of this study was to examine the effect of abscisic acid (ABA), sucrose, and auxin on grape fruit development and to assess the mechanism of these three factors on the grape fruit ripening process. Different concentrations of ABA, sucrose, and auxin were used to treat the grape fruit, and the ripening-related indices, such as physiological and molecular level parameters, were analyzed. The activity of BG protein activity was analyzed during the fruit development. Sucrose, ABA, and auxin influenced the grape fruit sugar accumulation in different ways, as well as the volatile compounds, anthocyanin content, and fruit firmness. ABA and sucrose induced, but auxin blocked, the ripening-related gene expression levels, such as softening genes PE, PG, PL, and CELL, anthocyanin genes DFR, CHI, F3H, GST, CHS, and UFGT, and aroma genes Ecar, QR, and EGS. ABA, sucrose, and glucose induced the fruit dry weight accumulation, and auxin mainly enhanced fruit dry weight through seed weight accumulation. In the early development of grape, starch was the main energy storage; in the later, it was glucose and fructose. Sucrose metabolism pathway-related gene expression levels were significant for glucose and fructose accumulation. BG protein activity was important in the regulation of grape ABA content levels. ABA plays a core role in the grape fruit development; sucrose functions in fruit development through two pathways: one was ABA dependent, the other ABA independent. Auxin blocked ABA accumulation to regulate the fruit development process.

QTL Analysis in Aromatic Rice of Assam, India

The study was carried out to identify quantitative trait loci (QTLs) controlling 12 morphological traits in rice using a F2 derived from Ranjit and Kola Joha cross. A framework linkage map of 1387.9cM was developed using 102 SSR markers and other few markers linked to aroma. QTL analysis based on composite interval mapping identified 24 QTLs was for 12 traits. Among them two QTLs were identified for grain aroma each on chromosome 5 and chromosome 8, out of which the QTLs between Aro1-BAD2 is in similar position with aroma gene of Basmati rice. Most of the QTLs identified in the current study, showed a range of partial to over-dominance effects, indicating complexity of the traits under consideration. Some genomic regions were associated with more than one trait, indicating linkage and/or pleiotropic effects. Marker linked to the QTLs can be considered for use in marker assisted breeding as being confirmatory to other reports.

Development of advanced fragrant rice lines from MR269 × Basmati 370 through marker-assisted backcrossing

Fragrance in rice is an appealing attribute to consumers. The increasing demand for fragrant rice highlights the need to develop fragrant rice variety that suit the preference of local consumers in addition to reduce fragrant rice imports. Marker-assisted backcrossing (MABC) was employed to develop advanced fragrant rice lines from the cross between MR269 and Basmati 370. MR269 is a Malaysian high-yielding rice variety but non-fragrant and was used as recurrent parent whereas Basmati 370 is a well-known fragrant traditional rice variety and was used as donor parent for the fragrance gene. Two generations of backcrosses and a generation of selfing were conducted to introgress the fragrance gene and restore the recurrent parent genome in the backcross progenies. As a result, 14 advanced fragrant rice lines were developed. These advanced fragrant rice lines carried homozygous alleles for the fragrance gene, similar to Basmati 370. The average recovery of recurrent parent genome was 88.4%. Besides being fragrant, the advanced fragrant rice lines also had most of the morphological and agronomical traits similar to MR269. Grain quality of the advanced fragrant rice lines in terms of gelatinization temperature, amylose content and gel consistency are also similar to both parents. Besides, the advanced fragrant rice lines had 2-acetyl-1-pyrroline content similar to Basmati 370. MABC approach applied in this study has successfully introgressed the fragrance gene and accelerated the recovery of recurrent parent genome in advanced fragrant rice lines, therefore these lines can be delivered to the farmers and consumers for use in due time.

Marker-assisted breeding of the rice restorer line Wanhui 6725 for disease resistance, submergence tolerance and aromatic fragrance.

BackgroundRice is a staple food crop in the world. With the increase in world population and economic development, farmers need to produce more rice in limited field. However, the rice production is frequently affected by biotic and abiotic stresses. The use of natural disease resistance and stress tolerance through genetic breeding is the most efficient and economical way to combat or acclimate to these stresses. In addition, rice with aromatic fragrance can significantly increase market value for its good grain quality. Mianhui 725 (MH725) is an elite restorer line that has been widely used to produce three-line hybrid rice in China. We previously introduced rice bacterial blight resistance genes Xa4 and Xa21 into MH725 and obtained an introgression rice line Wanhui 421 (WH421), which theoretically possesses 96.9% genetic background of MH725.ResultsHere we report the introduction and pyramiding of disease resistance genes Xa27 and Pi9, submergence tolerance gene Sub1A and aromatic fragrance gene badh2.1 in WH421 through backcrossing and marker-assisted selection. The newly developed introgression rice line was designated as Wanhui 6725 (WH6725), which theoretically possesses 95.0% genetic background of MH725. WH6725 and its hybrid rice conferred disease resistance to both blast and bacterial blight diseases and showed tolerance to submergence for over 14 days without significant loss of viability. Compared with non-aromatic rice MH725, WH6725 has strong aromatic fragrance. The major important agronomic traits and grain quality of WH6725 and its hybrid rice obtained in field trials were similar to those of MH725 and the control hybrid rice, indicating that WH6725 is as good as MH725 when it is used as a restorer line for three-line hybrid rice production.ConclusionWe have successfully developed a new restorer line WH6725 with disease resistance to rice blast and bacterial blight, tolerance to submergence and aromatic fragrance, which can be used to replace MH725 for hybrid rice production.

An analysis of variation of the aroma gene in rice (Oryza sativa L. subsp. indica Kato) landraces

The candidature of 8-bp deletion in badh2 gene as the predominant cause for aroma development in rice was investigated in 84 subsp. indica rice landraces. Presence of this functional mutation was detected in 80 % of aromatic samples and in three non-aromatic landraces which were found to be heterozygous at this locus. However, 11 landraces did not show its presence despite being aromatic during qualitative assessment. None of the wild ancestors possessed this deletion. Finally, we have discussed implications of our findings in the broader context of aroma evolution.

Combined physiological, transcriptome, and cis-regulatory element analyses indicate that key aspects of ripening, metabolism, and transcriptional program in grapes (Vitis vinifera L.) are differentially modulated accordingly to fruit size.

BackgroundIn wine grape production, management practices have been adopted to optimize grape and wine quality attributes by producing, or screening for, berries of smaller size. Fruit size and composition are influenced by numerous factors that include both internal (e.g. berry hormone metabolism) and external (e.g. environment and cultural practices) factors. Combined physiological, biochemical, and transcriptome analyses were performed to improve our current understanding of metabolic and transcriptional pathways related to berry ripening and composition in berries of different sizes.ResultsThe comparison of berry physiology between small and large berries throughout development (from 31 to 121 days after anthesis, DAA) revealed significant differences in firmness, the rate of softening, and sugar accumulation at specific developmental stages. Small berries had significantly higher skin to berry weight ratio, lower number of seeds per berry, and higher anthocyanin concentration compared to large berries. RNA-sequencing analyses of berry skins at 47, 74, 103, and 121 DAA revealed a total of 3482 differentially expressed genes between small and large berries. Abscisic acid, auxin, and ethylene hormone pathway genes were differentially modulated between berry sizes. Fatty acid degradation and stilbenoid pathway genes were upregulated at 47 DAA while cell wall degrading and modification genes were downregulated at 74 DAA in small compared to large berries. In the late ripening stage, concerted upregulation of the general phenylpropanoid and stilbenoid pathway genes and downregulation of flavonoid pathway genes were observed in skins of small compared to large berries. Cis-regulatory element analysis of differentially expressed hormone, fruit texture, flavor, and aroma genes revealed an enrichment of specific regulatory motifs related to bZIP, bHLH, AP2/ERF, NAC, MYB, and MADS-box transcription factors.ConclusionsThe study demonstrates that physiological and compositional differences between berries of different sizes parallel transcriptome changes that involve fruit texture, flavor, and aroma pathways. These results suggest that, in addition to direct effects brought about by differences in size, key aspects involved in the regulation of ripening likely contribute to different quality profiles between small and large berries.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2660-z) contains supplementary material, which is available to authorized users.

Modulation of the Fragrance of Kam Sweet Rice by Jasmonic Acid and Abscisic Acid Might Involve the MYC2 and ABI5 Transcription Factors

Volatile compounds were analyzed using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). Results showed that nonanal had the highest odor activity value in the filling grains. Nonanal was enhanced by application of JA and inhibited by ABA in the seedlings of Kam sweet rice. C9-aldehydes are significant odorants in many rice types and known products of the 9-lipoxygenase and 9-hydroperoxide lyases encoded by the OsLOX3 and OsHPL1 genes, respectively. OsLOX3 mRNA expression was higher in aromatic rice compared to a nonaromatic cultivar. mRNA expression of ABI5 and MYC2 negatively correlated with OsLOX3 expression (r = −0.841, P < 0.01; and r = −0.512, P < 0.05). In conclusion, the transcription factors ABI5 and MYC2 might be involved in ABA and JA modulation of nonanal biosynthesis, which could be used to improve rice quality. Practical Applications Nonanal and 2-acetyl-1-pyrroline are important and potent flavor compounds in aromatic Kam sweet rice. The OsLOX3 gene was potentially identified as a critical gene in aromatic Kam sweet rice and the enhancing effect of JA on nonanal biosynthesis was confirmed. The transcription factors ABI5 and MYC2 seem to regulate the expression of the fragrance gene OsLOX3 while MYC2 act as a positive regulator involved in JA-mediated nonanal biosynthesis. ABI5 participate in the ABA signaling pathway to down-regulate the expression of OsLOX3. These results will help understand the pathways involved in the biosynthesis of rice fragrance, which could be used to improve the quality of rice.

Identification of fragrance gene in some elite advance lines of rice cultivated in foothills of the Himalayas

Identification of fragrance gene in some elite advance lines of rice cultivated in foothills of the Himalayas

Single base substitution causing the fragrant phenotype and development of a type-specific marker in aromatic coconut (Cocos nucifera).

The fragrance gene, betaine aldehyde dehydrogenase 2 (Badh2), has been well studied in many plant species. The objectives of this study were to clone Badh2 and compare the sequences between aromatic and non-aromatic coconuts. The complete coding region was cloned from cDNA of both aromatic and non-aromatic coconuts. The nucleotide sequences were highly homologous to Badh2 genes of other plants. Badh2 consisted of a 1512-bp open reading frame encoding 503 amino acids. A single nucleotide difference between aromatic and non-aromatic coconuts resulted in the conversion of alanine (non-aromatic) to proline (aromatic) at position 442, which was the substrate binding site of BADH2. The ring side chain of proline could destabilize the structure leading to a non-functional enzyme. Badh2 genomic DNA was cloned from exon 1 to 4, and from exon 5 to 15 from the two coconut types, except for intron 4 that was very long. The intron sequences of the two coconut groups were highly homologous. No differences in Badh2 expression were found among the tissues of aromatic coconut or between aromatic and non-aromatic coconuts. The amino acid sequences of BADH2 from coconut and other plants were compared and the genetic relationship was analyzed using MEGA 7.0. The phylogenetic tree reconstructed by the Bayesian information criterion consisted of two distinct groups of monocots and dicots. Among the monocots, coconut (Cocos nucifera) and oil palm (Elaeis guineensis) were the most closely related species. A marker for coconut differentiation was developed from one-base substitution site and could be successfully used.

Genomics-Based Discovery of Plant Genes for Synthetic Biology of Terpenoid Fragrances: A Case Study in Sandalwood oil Biosynthesis.

Terpenoid fragrances are powerful mediators of ecological interactions in nature and have a long history of traditional and modern industrial applications. Plants produce a great diversity of fragrant terpenoid metabolites, which make them a superb source of biosynthetic genes and enzymes. Advances in fragrance gene discovery have enabled new approaches in synthetic biology of high-value speciality molecules toward applications in the fragrance and flavor, food and beverage, cosmetics, and other industries. Rapid developments in transcriptome and genome sequencing of nonmodel plant species have accelerated the discovery of fragrance biosynthetic pathways. In parallel, advances in metabolic engineering of microbial and plant systems have established platforms for synthetic biology applications of some of the thousands of plant genes that underlie fragrance diversity. While many fragrance molecules (eg, simple monoterpenes) are abundant in readily renewable plant materials, some highly valuable fragrant terpenoids (eg, santalols, ambroxides) are rare in nature and interesting targets for synthetic biology. As a representative example for genomics/transcriptomics enabled gene and enzyme discovery, we describe a strategy used successfully for elucidation of a complete fragrance biosynthetic pathway in sandalwood (Santalum album) and its reconstruction in yeast (Saccharomyces cerevisiae). We address questions related to the discovery of specific genes within large gene families and recovery of rare gene transcripts that are selectively expressed in recalcitrant tissues. To substantiate the validity of the approaches, we describe the combination of methods used in the gene and enzyme discovery of a cytochrome P450 in the fragrant heartwood of tropical sandalwood, responsible for the fragrance defining, final step in the biosynthesis of (Z)-santalols.

Comparative analysis of eating quality and yield of selected non-waxy red-pericarp aromatic rice mutants

Red-pericarp variety Kuanfu waxy aroma is highly valued for its grain quality in Taiwan, but it has undesirable traits of awned rough grain and taller plant height. The present study compared the palatability of cooked rice grains and yields of Kuanfu waxy aroma and its ten NaN 3 -induced awnless non-waxy aromatic M 6 -generation mutants developed through single-seed-descent selection (from M 2 to M 6 generation) plus a non-waxy aromatic rice variety TNG71 (reference variety with good eating quality). The palatability of cooked rice grains was assessed by using a rice taste meter. Results indicated that all the mutants exhibited awnless grain traits and reduced plant height. PCR analyses confirmed the expression of fragrance ( fgr ) gene in these mutants. Significant differences in the palatability of cooked rice were also observed among the mutants with AM-425 (70.45) and AM-430 (73.75) having higher palatability scores than TNG71 (69.32). Mutant AM-425 also had higher aroma sensory score (1.33) than TNG71 (1.17). Two years yield trials indicated that AM-425 and AM-430 significantly out-yielded Kuanfu waxy aroma and can be recommended to rice growers.

Identification of Aroma Gene (Mutated &lt;i&gt;badh&lt;/i&gt;2) and Properties of Aroma on Aromatic BC&lt;sub&gt;5&lt;/sub&gt;F&lt;sub&gt;2&lt;/sub&gt; Ciherang

Aromatic rice varieties have some weaknesses such as low productivity, and less resistant to pests and diseases. This study aimed to obtain homozygous strain of BC5F2 Ciherang aromatic through the identification of aroma gene (mutated badh2) and properties of the aroma. Ciherang paddy (nonaromatic paddy) was used as the female parent, whereas Mentik Wangi paddy (aromatic paddy) was used as the male parent. The experiment was conducted in BC5F2 because it is expected to generate plants with properties 98.4% close to female parent. The DNA from five strains of paddy plants BC5F2Ciherang X Mentik Wangi was isolated by a modified CTAB method. The concentration of DNA was determined by measuring absorbance at 260 nm wavelength, while its purity was determined from the ratio of the absorbance at a wavelength of 260/280 nm. PCR-based molecular selection was done by using the Bradbury primers. PCR results showed that of the 250 samples, there were 66 samples had DNA fragment of the same size as that of Mentik Wangi, i.e. 257 bp, 67 samples had the same size as the DNA fragment of Ciherang, i.e. 355 bp, and 117 samples had the same size with the both of DNA fragments, i.e. 257 bp and 355 bp. Plants with amplified 257 bp DNA fragment was subjected to leaf aroma test using 1.7% KOH. The results showed that 42 positive samples, out of 66 samples. Samples positive on leaf aroma test were tested again on rice aroma test. Rice aroma test results showed the majority (85.4%) samples that are positive on leaf aroma test is also positive on the rice aroma test.

The Fungal Aroma Gene ATF1 Promotes Dispersal of Yeast Cells through Insect Vectors

Yeast cells produce various volatile metabolites that are key contributors to the pleasing fruity and flowery aroma of fermented beverages. Several of these fruity metabolites, including isoamyl acetate and ethyl acetate, are produced by a dedicated enzyme, the alcohol acetyl transferase Atf1. However, despite much research, the physiological role of acetate ester formation in yeast remains unknown. Using a combination of molecular biology, neurobiology, and behavioral tests, we demonstrate that deletion of ATF1 alters the olfactory response in the antennal lobe of fruit flies that feed on yeast cells. The flies are much less attracted to the mutant yeast cells, and this in turn results in reduced dispersal of the mutant yeast cells by the flies. Together, our results uncover the molecular details of an intriguing aroma-based communication and mutualism between microbes and their insect vectors. Similar mechanisms may exist in other microbes, including microbes on flowering plants and pathogens.