Khao Dawk Mali Research Articles

Rapid Variety Identification of Pure Rough Rice by Fourier‐Transform Near‐Infrared Spectroscopy

ABSTRACTRice variety is considered as an important factor influencing cooking and processing quality because of variations in size, shape, and constitution. Difficulty in management of rough rice with lower varietal purity becomes a significant problem in rice production and can result in the reduction of rice quality. Fourier‐transform near‐infrared (FT‐NIR) spectroscopy was used to identify the variety of rough rice through whole‐grain techniques. Moist rough rice samples (n = 259) comprising five varieties (Khao Dawk Mali 105 [KDML105], Pathum Thani 1, Suphan Buri 60, Chainat 1, and Pitsanulok 2) were gathered from different locations around Thailand and scanned in the NIR region of 9088–4000 cm–1 in reflectance mode. Soft independent modeling of class analogies (SIMCA) and partial least squares discriminant analysis (PLSDA) methods were used for identification by utilizing preprocessed spectra. The highest identification accuracy achieved was 74.42% by the SIMCA model and 99.22% by the PLSDA model. The best PLSDA model demonstrated approximately 97% correct identification for KDML105 samples and 100% for the others. This study raises the possibility of applying FT‐NIR spectroscopy as a nondestructive technique for rapidly identifying moist rough rice varieties in routine quality assurance testing.

Screening of Resistance Genes Linked to Brown Planthopper Using STS Marker in Aromatic Rice Germplasm

Brown planthopper (BPH) is a serious insect pest of rice crop throughout rice growing countries, and yield loss due to its infection can be up to 60%. This study aimed to evaluate efficiency of molecular markers for screening BPH resistance accessions among 86 aromatic rice germplasm Eighty-six accessions of aromatic rice germplasm included two accessions of Tongil type (bred in Korea), 28 accessions of japonica type and 56 accessions of indica type. We applied eight STS markers (pBPH9, pBPH19, pBPH20, pBPH21, AJ09-b, RG457L, RG457B, and 7312.T4A) which were linked to four of BPH resistance genes, Bph1, Bph13(t), Bph10, and Bph18(t) respectively. One japonica type accession, 415XIr352, and six indica type accessions possessed one or four positive bands when tested with four STS markers linked to Bph1 gene. One indica type aromatic rice, Basmati9-93, showed the target bands linked to the Bph10 gene. The other accessions did not show same fragments as the respective resistant lines. Bph13(t) is the most widely introduced resistance gene and only one accession showed positive bands implying that this accession might harbor Bph10 and Bph18(t) genes. Three aromatic accessions, Domsiah, Khao Dawk Mali 105 and 415XIr352 showed gene pyramiding of Bph1 and Bph13(t). Two indica aromatic rice, Ds 20 and Basmati 9-93, possessed at least two BPH resistance genes, Bph1, Bph18(t) and Bph13(t), Bph18(t), respectively. These results indicates that aromatic rice germplasm have narrow diversities of BPR resistance genes.

Changing allele frequencies associated with specific resistance genes to leaf blast in backcross introgression lines of Khao Dawk Mali 105 developed from a conventional selection program

Key genomic regions associated with blast resistance against a broad spectrum of isolates could be identified in backcross introgression lines developed by conventional breeding program. In this article, eighty three BC 3F 2 backcross introgression lines (BILs) derived from a cross between IR68835-98-2-B-2-1-1 (a broad spectrum blast resistance variety) and KDML105 (a susceptible variety) were developed by phenotypic selection against a mixture of six virulent blast isolates (MXL) that are widely spread out in the rainfed lowland of the North and Northeast of Thailand. The resistance spectrum of the BILs was assessed by inoculating with 12 different Magnaporthe oryzae isolates that showed differential responses on the parental cultivars and the MXL that was used for phenotypic selection. All BILs showed highly resistant reactions (low disease score) to the MXL and to two blast isolates THL48 and THL149. Four markers, i.e., RM246, RM241, RM303 and RM164 completely favoring the IR68835 allele (shifting of allele frequencies from KDML105 to IR68835) were identified on chromosomes 1, 4 and 5, respectively. Therefore, these markers could be linked to the resistance genes functioning against the MXL, THL48 and THL149. Furthermore, significant shifting of alleles was identified at six markers located on chromosomes 2, 4, 8, 9 and 12. Seven DNA markers linked to specific resistance genes were identified, in which allele from IR68835 at 6 markers, i.e., RM6, RM205, RM211, RM252, RM273 and RM342 reduced disease score (DS), against blast isolates THL16, THL329, THL458, THL831, THL868 and THL96036 while allele from KDML105 at RM208 ( Pi-kd on chromosomes 2) reduce DS against THL84, THL191, THL557 and THL1108. In this study, the use of DNA markers enabled the identification of specific resistance genes in the backcross breeding materials developed from routine rice breeding program through the conventional phenotypic selection. In this experiment, the usefulness of breeding materials from conventional breeding program in identifying genes corresponding to the selection was illustrated. Linked markers and their genomic location provide necessary information for further use of marker-assisted selection to improve blast resistance in rice breeding program.

米の炊飯過程における水分分布の視覚的・定量的把握

As heating proceeds during the cooking of rice, starch granules within the rice grains absorb water, swell, and then gelatinize. To determine the optimal cooking conditions for various kinds of rice, it is desirable to be able to detect differences in the water absorption of rice grains during cooking. NMR imaging was used to follow changes in the content and distribution of water during the cooking of Nipponbare (Japonica), Khao Dawk Mali (Indica) and High Amylose (Indica) rice. Samples were cooked for various cooking times in closed-glass vials, quenched to stop the cooking process, and then investigated using two-dimensional multi-echo 1H imaging at room temperature. Images obtained from the first-echo revealed changes in the water distribution of the rice grains. T2 images calculated using the echoes were converted into quantitatively reliable contour maps of the water concentrations using an empirical T2 vs. water content calibration determined from a series of water/rice starch mixtures. Japonica rice samples with different milled ratios were also investigated to observe the effect of rice grain husks on water absorption. The degree of gelatinization of rice during cooking was measured by the β-amylase·pullulanase method (BAP) and Fourier-transform infrared spectroscopy (FT-IR/ATR). An FT-IR peak seen at around 1 000 cm-1 increased with increasing cooking time. There was a high correlation in the degree of gelatinization between the FT-IR method and the BAP method.

Screening upland rice (Oryza sativa L. ssp. indica) genotypes for salt-tolerance using multivariate cluster analysis

Seedlings of thirteen genotypes of rice were photoautotrophically grown on MS medium and subsequently exposed to 0 (control) or 200 mM NaCl (salt stress) for 14 days. Chlorophyll a (Chla), chlorophyll b (Chlb) and total carotenoids (Cx+c), in the salt stressed leaves of all genotypes decreased significantly, but the extent of the decrease varied among different genotypes. Maximum quantum yield of photosystem II (PSII) (Fv/Fm), photon yield of PSII (FPSII) and net photosynthetic rate (Pn) in salt stressed seedlings of all genotypes dropped significantly, whereas FPSII in cv. Homjan (HJ), Dokpayom (DPY), Chewmaejan 2 (CMJ2) and upland rice 1 (UR1) were alleviated. Moreover, growth parameters including shoot height, root length, fresh weight, dry weight and leaf area in salt stressed plantlets of all genotypes were significantly inhibited. The pigment degradation, photosynthetic abilities and growth inhibition in saline regimes were subjected to hierarchical cluster analysis, which lead to the classification of Kumuangluang (KML), Khao Dawk Mali (KDML), Pokkali (POK), HJ, DPY, Chewmaejan 1 (CMJ1), CMJ2, UR1 and Chowho (CH) as salt tolerant and R258, Pathumthani 1 (PT1), IR29 and upland rice 2 (UR2) as salt sensitive.

Proline biosynthetic gene expression in tissue cultures of rice (Oryza sativa L.) in response to saline treatment

The regulation of proline biosynthesis has been examined in callus and cell cultures of the indica-type rice cultivar Khao Dawk Mali 105 (KDML105) in response to a saline treatment (250 mM NaCl) in terms of the expression of Δ1-pyrroline-5-carboxylate reductase (OsP5CR) and members of the gene family encoding the rate-determining enzyme, Δ1-pyrroline-5-carboxylate synthase (designated OsP5CS1 and OsP5CS2). Using friable callus, growth was retarded by treatment with 250 mM NaCl within 4 days, with a significant increase in the expression of OsP5CS2 by 24 h, and a less marked induction in OsP5CS1 and OsP5CR over the same time-course. Cell suspension cultures derived from the friable callus were also treated with 250 mM NaCl and an induction in OsP5CS2 was again observed, although this was not as marked as in the friable callus, and there was no significant change in OsP5CS1 and OsP5CR expression. This is the first report that details the expression of OsP5CS1 and OsP5CS2 in tissue culture and the results show that, in common with whole plants, OsP5CS2 displays a primacy of response to saline treatment. However, this response may require a community of communicating cells, as occurs in callus tissue, rather than cell suspension cultures. This difference has implications both in terms of the biology of signaling in response to increased salinity and in the use of tissue culture to screen for saline-tolerant germplasm.

Volatile profiles of aromatic and non-aromatic rice cultivars using SPME/GC–MS

Rice ( Oryza sativa L.) is enjoyed by many people as a staple food because of its flavour and texture. Some cultivars, like scented rice, are preferred over others due to their distinctive aroma and flavour. The volatile profile of rice has been explored by other investigators, some of whom have also determined a corresponding aroma using GC/olfactometry. However, little research has been done to determine if different aromatic rice cultivars produce different flavour volatiles that would make them more desirable than others when cooked. In this study, seven aromatic and two non-aromatic cultivars were examined for their volatile profiles both before and after storage using solid phase microextraction (SPME) fibres in conjunction with gas chromatography/mass spectrometer (GC–MS). Ninety-three volatile compounds were identified, 64 of which had not been previously reported in rice. Differences were found in the volatile compounds of aromatic and non-aromatic rice besides 2-acetyl-1-pyrroline (2-AP). Most of the volatile compounds were present in freshly harvested rice and rice following storage, with very few new compounds being identified only after storage. Dellrose, an aromatic cultivar, and Cocodrie, a non-aromatic cultivar, had the most complex volatile profiles (over 64 volatiles). Sixteen compounds were found only in the aromatic cultivars, and some volatiles were found to be unique to specific aromatic cultivars. However, no distinctive pattern was observed that would identify a cultivar as being derived from Basmati, Khao Dawk Mali 105 (i.e. jasmine), or other sources of aroma. This study showed that there is a great diversity of volatiles in both aromatic and non-aromatic rice cultivars and, with further research, this may lead to a better understanding of the combination of compounds that gives a cultivar a unique flavour.

An Improved Process for High Quality and Nutrition of Brown Rice Production

Germinated brown rice (GBR) of two popular Thailand varieties, Khao Dawk Mali 105 (KDML 105) and Chainat 1, with improved nutritional composition, was obtained by optimizing water soaking conditions. Different water pH (3, 4, 6 and 8), temperatures (25 °C, 35 °C and 45 °C), and soaking times (12 and 24 h) were tested. Using the response surface methodology (RSM), the best condition for producing GBR of both varieties was soaking in water with pH 6 and temperature of 35 °C for 24 h. It caused a 4- to 5-fold increase in gamma-amino butyric acid (GABA) content which, together with protein and lipid contents, were highest among treatments. Intermediate levels of thiamine (vitamin B1) and phytic acid (IP6) were obtained. In GBR of KDML 105 variety, GABA, vitamin B1 and IP6 contents were 16.48, 0.526 and 501.06 mg/100 g, respectively, while protein and lipid contents were 10.50% and 4.00%, respectively. For Chainat 1 variety, GABA, vitamin B1 and IP6 contents were 14.50, 0.436 and 486.03 mg/100 g, respectively, while protein and lipid contents were 9.80% and 3.99%, respectively. Carbohydrate and amylose contents differed by only less than 1-2% among treatments. Supplemental aeration during water soaking decreased GABA, protein and lipid contents, but increased vitamin B1 and IP6 contents in both varieties. Furthermore, cooked GBR of both varieties had softer texture than cooked ordinary brown rice.

Evaluation of aroma in rice(Oryza sativa L.) using KOH method, molecular markers and measurement of 2-acetyl-1-pyrroline concentration

The sensory test of leaf aroma using a 1.7% KOH solution for 70 rice cultivars originating from nine Asian countries indicated the existence of a strong correspondence of the aroma character with the tasting of individual grains. The sensory test appeared to be a simple and reliable method for rapid identification of aromatic rice. We could not find any universal specific molecular marker suitable for the identification of the aroma trait in rice although the SSR marker RM17 could distinguish the aromatic Vietnamese cultivars. We used three F2 populations of aromatic and nonaromatic cultivars as parents to study the mode of inheritance of the aroma trait. Monogenic recessive inheritance of the aroma trait was observed in Jasmine 85 and Khao Dawk Mali 105, whereas Hoa Lai harbored two recessive genes for the aroma trait. Quantitative analysis of the aromatic compound 2-acetyl-1-pyrroline suggested that the expression of the aroma trait was controlled by different genetic factors in addition to the influence of environmental conditions. These results confirmed that aroma in rice is a quantitative character and that several genes are involved in the expression of the aroma trait in rice.

Evaluation of Bacterial Blight Resistance Using SNP and STS Marker-assisted Selection in Aromatic Rice Germplasm

A molecular survey was conducted to identify the presence of the bacterial blight resistance genes (Xa1, Xa4, xa5, xa13 and Xa21) in 86 accessions of aromatic rice obtained from germplasm. The results revealed that the resistance gene Xa4 (32.5%), Xa21 (17%), and xa5 (16%) were widely observed in tested rice germplasm. Among tested rice germplasm, 49 accessions showed the presence of more than one of five R genes, and 37 accessions possessed none of the R gene. TALLi and 05-IRRi-M-46 showed the presence of Xa4, xa5, xa13 and Xa21. Rice race <TEX>$415{\times}Ir352$</TEX> exhibited positive amplicon for the Xa1, Xa4, xa5 and Xa21. Hyangmibyeo1hos, Ir841-85-1-1-2 and Jasmine85 showed the positive amplicon for the Xa1, Xa4 and xa5 genes. Yekywin Yinkya Hmwe and Khao Dawk Mali105 showed the presence of Xa1, Xa4 and Xa21 gene. Masino Basmati showed the presence of xa5, xa13, Xa21 genes. Xa1 and Xa21 genes were noticed in Mihayngbyeo, Tarana Deshi, Mayataung and AZUCENA. Hyangmibyeo2ho, Basmati 6311 and Basmati405 possessed only two R genes such as Xa4 and xa5, and xa5 and xa13, respectively. The evaluation results of bacterial blight resistance genes in aromatic rice germplasm will help in breeding of multi disease resistant varieties.

Antioxidant capacities and phenolic compounds of the husk, bran and endosperm of Thai rice

Four fractions, namely, rice bran, rice husk, brown rice and milled rice of a Thai rice variety (Khao Dawk Mali 105), collected from three different growth sites, were analysed to determine phenolic acid composition, γ-oryzanol and tocopherols content and their antioxidant capacity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing ability power (FRAP) assays. The bran and husk fractions showed higher values of antioxidant activity based on the DPPH and FRAP assays, compared to the other fractions. In addition, the bran fraction had the highest γ-oryzanol and tocopherols content. On the other hand, the husk fraction showed a greater phenolic acids concentration than the other fractions. The three major phenolic acids found in all fractions, despite different growth sites, were ferulic, vanillic and p-coumaric acids. Ferulic acid was most evident in the bran, whereas vanillic and p-coumaric acids were mostly found in the husk. Significant differences (p < 0.05) in the antioxidant capacities of each fraction depended on the growth sites and antioxidant components. We propose that variation in phenolic acid content could be affected by the growth sites. This study demonstrates that rice bran and husk can be considered as valuable sources of bioactive components with high antioxidant properties.

Multi-Pass Sorption Drying of Paddy Using Rice Husk Adsorbent: Experiments and Simulation

A single-stage sorption drying of paddy with rice husk adsorbent cannot reduce its moisture content to a safe level since the relative humidity of air inside the mixing tank is very high. To obtain a safe moisture content, multi-pass sorption drying was used and the effect of operating parameters—i.e., rice husk density, rice husk initial moisture content, and volumetric mixing ratio of paddy to rice husk—on the drying time and paddy quality were investigated for two paddy varieties, Suphanburi 1 and Khao Dawk Mali 105. A mathematical model associated with the transfers of heat and mass between the grain and adsorbent was also formulated to explore the sensitivity of the operating parameters to the drying time. Both the experiment and the simulation showed that the drying time was shorter by using a lower initial moisture content of rice husk, a higher rice husk bulk density, and a higher volumetric mixing ratio, the last factor being less important. For quality assessment, the color of white rice for both paddy varieties changed insignificantly under the influence of all the operating parameters, but the head rice quality was rather sensitive to the operating conditions especially for the Khao Dawk Mali 105, which had a 6–10% lower in head rice yield compared to that of the reference samples.

Textural Properties and Structures of Starches from Indica and Japonica Rice with Similar Amylose Content

The difference in stickiness between cooked Nipponbare (Japonica rice) and Khao Dawk Mali (Indica rice) that have similar apparent amylose content was investigated, and the fine structure of starch in both cooked rice and extract from the surface of cooked rice was analyzed. Non-sticky high-amylose rice (Indica rice) was also studied for comparison. The solid content and amount of amylopectin in the extract from the surface of cooked Nipponbare were the highest, followed by cooked Khao Dawk Mali, and cooked high-amylose rice. This difference in solid content and the amount of amylopectin contributed to the stickiness of cooked Nipponbare. This suggests that the stickiness of cooked rice is less when less amylopectin is dissolved into cooking water, even when the amylose content and fine structure of the starch in the rice grains is similar. Thus, cooked Khao Dawk Mali is less sticky than cooked Nipponbare, despite having similar amylose content.

Isolation and Some Characteristics of Lipoxygenase from Aromatic Brown Rice (Oryza Sativa L.) cv. Khao Dawk Mali 105

Lipoxygenase from Khao Dawk Mali 105 aromatic brown rice was isolated by extracting brown rice liquid nitrogen powder using 0.2 M phosphate buffer pH 7, fractionating with 30–60% (NH4)2SO4, dialyzing and gel filtration on Sephadex G-200. The optimum pHs for dialyzed lipoxygenase activity were around 7.5 and 9.5. The enzyme appeared to be completely inactivated after heating 30 min at 70°C, 20 min at 80°C and 10 min at 90°C. The enzyme could be inhibited by MgCl2, ZnCl2, KCl, BHA, vitamin E, vitamin C, and BHT; however, CaCl2 acted as the enzyme activator.

Development of rice introgression lines with brown planthopper resistance and KDML105 grain quality characteristics through marker-assisted selection

‘Khao Dawk Mali 105’ (KDML105), a Thai aromatic rice cultivar, has been accepted in markets as a prime jasmine rice with premium prices. It has been extensively used as a parental line to develop new cultivars for rainfed lowland areas in Thailand because of its favorable quality and fragrance. However, this cultivar is highly susceptible to brown planthopper (BPH), a phloem sap-feeding insect pest of rice. The main objective of this study was to combine KDML105 essential grain quality traits with BPH resistance from the donor cultivar, ‘Rathu Heenati’. The linkage drag between Bph3 and Wx a alleles was successfully broken by phenotypic and marker-assisted selections. All introgression lines (ILs) developed in this study showed a broad spectrum resistance against BPH populations in Thailand and had KDML105 grain quality standards. Finally this study was revealed that the ILs can be directly developed into BPH resistant varieties or can be used as genetic resources of BPH resistance to improve rice varieties with the Wx b allele in rice breeding programs.

The Perspective Effects of Various Seed Coating Substances on Rice Seed Variety Khao Dawk Mali 105 Storability I: The Case Study of Physiological Properties

This study aimed to evaluate the perspective changes of several physiological performances of rice seeds cv. KDML 105 which were coated with various seed coating substances [chemical fungicide, captan (CA) and biological coating polymers; chitosan-lignosulphonate polymer (CL) and eugenol incorporated into chitosan-lignosulphonate polymer (E + CL)] during storage (12 months). CA significantly increased seed moisture content and seed water activity through out the storage period. The qualities and viability of the seeds were seriously declined by this treatment. Moreover, CA inhibited the shoot and root development, seedling dry weight accumulation, delayed the seed germination and seedling growth rate. CA treated seeds were susceptible to stress conditions that declined the seed germination potential under cold, high moisture and temperature stress conditions. Nevertheless, CL and E + CL coating polymer could maintain seed storability, which significantly improved seed germination and seedling performances. These improvements were attributed to maintain the nutritive reserve and dehydrogenase activity in seeds. Moreover, the biological seed treatment stimulated the embryo growth and so speeding up the seedling emergence when compared untreated seeds.

CHANGES IN QUALITY OF RICE (ORYZA SATIVA L.) CV. KHAO DAWK MALI 105 DURING STORAGE

Rice has been the main staple in Thailand for many centuries. Rice is also the main export produce of Thailand, with many varieties exported each year. Recently, the main focus of research has been the rice variety known as Khao Dawk Mali 105 (KDML 105) because of its aroma, with evidence showing this aroma could hold the key to rice stability which could extend its shelf life for longer storage and preservation. Because of the volatile nature of this aroma, we investigated how storage affects the quality of this rice by monitoring the amount of 2-acetyl-1 -pyrroline (2AP) over a period of 8 months. The pasting properties of KDML 105 following storage of up to 8 months showed a significant time effect at P ≤ 0.05. Breakdown viscosity was 51% after 8 months storage while setback viscosity and hardness increased during storage. The amount of 2AP decreased to 7% at 8 months while hardness increased proportionately. The number of high molecular weight protein bands increased as rice was aged for 5 and 8 months. In vitro digestibility of starch in fresh and 1-year aged rice were not significantly different.

Quantitative NMR imaging study of the cooking of Japonica and Indica rice

Abstract NMR imaging was used to follow changes in the water content and distribution during the cooking of Nipponbare (Japonica), Khao Dawk Mali (Indica) and High Amylose (Indica) rice. Samples were cooked in closed glass vials for various times, quenched to stop cooking and then investigated using two-dimensional multi-echo 1H imaging experiments at 20 °C. Images calculated from the first-echo revealed changes in the water content of the rice grains. T2 images calculated using the first 16 echoes were converted into quantitatively reliable contour maps of the water concentration using an empirical T2 vs. water content calibration determined from a series of water/rice starch mixtures. Considerable differences in the rate of water uptake and diffusion, the average water contents and the proportions of under-, optimally- and over-cooked rice were observed for the three rice types studied.

IRON RETENTION ON FLOUR GEL-COATED RICE GRAINS AND ITS STORAGE STABILITY

This study was conducted to determine the feasibility of iron fortification in rice grains by using rice flour gel as the coating polymer. Three iron compounds were used: ferrous sulfate (FS), ferric pyrophosphate (FP) and iron glycine (IG). After rinsing and steaming the rice (using 100 g of rice per 125 mL of water), the Khao Dawk Mali (KDML) 105 rice retained 96.82% of its iron content while Khum Doi Saket (KDSK), a dark red glutinous variety and which was presoaked for 6 h in water, lost 29% of its iron content. During a 9-month storage, the progressive percentage of peroxide values (POVs) of KDML 105 rice was higher than those of KDSK; FS catalyzed autoxidation at the fastest rate than FP and IG. FS increased POV in the enriched KDML 105 and KDSK rice at 11.6 and 2.1 meq oxygen/kg, respectively.

Effects of drying methods and storage time on the aroma and milling quality of rice ( Oryza sativa L.) cv. Khao Dawk Mali 105

The effects of drying methods and storage time on the aroma and milling quality of the aromatic rice, Khao Dawk Mali 105, stored as whole grains, were investigated in order to define the most appropriate post-harvest treatment for the rice. Among the six drying methods that were used, namely: modified air at 30 and 40 °C, hot air at 40, 50, and 70 °C, and sun-drying, the methods that employed lower temperature appeared to provide higher concentrations of the key aroma compound, 2-acetyl-1-pyrroline, and lower amounts of the off-flavour compounds, n-hexanal and 2-pentylfuran, regardless of the storage time. The sun-drying method yielded contrasting results. Overall, during 10 months storage, as the time increased, 2-acetyl-1-pyrroline concentrations decreased whereas n-hexanal and 2-pentylfuran contents increased. Head rice yield was most clearly affected in the sample dried by hot air at 70 °C, giving a percentage yield slightly less than half of those obtained by the other drying methods. However, no significant variation in the percentages of whiteness was observed among the rice samples obtained from the different drying methods and storage times.