Thai Rice Cultivars Research Articles

Quantification of Vanillin, Ethyl Vanillin and Methyl Vanillin Among Thai Rice Cultivars by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A method was developed and validated for vanillin, ethyl vanillin, and methyl vanillin determination in Thai rice cultivars by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) under the selected reaction monitoring mode. In rice samples, the limit of detection was 13.3, 11.2 and 5.0 mg/kg for vanillin, ethyl vanillin, and methyl vanillin. A high correlation coefficient was obtained (R2 = 0.9999, 0.9999 and 0.9998) within the linear range (0 - 300 mg/L) in the MS method. The recoveries ranging from 90.63 % ± 6.25 to 108.7 % ± 2.35 were obtained in different spiking concentrations. The average RSD% of intra-day for vanillin, ethyl vanillin, and methyl vanillin was 6.90, 5.13 and 2.16 %, and the inter-day were 6.72, 5.30 and 5.64 %, respectively. The developed method was applied to 24 commercial rice samples. Vanillin, were found in 24 samples ranging from 95.2 to 773.2 mg/kg. However, ethyl vanillin and methyl vanillin were not detected under LOD. The developed UPLC-MS/MS method for vanillin, ethyl vanillin and methyl vanillin determination include the merits of simple preparation steps and high sensitivity. HIGHLIGHTS Method development for analyzing vanillin, ethyl vanillin, and methyl vanillin in rice grain by UPLC-MS/MS. High accuracy and precision method for determining vanillin and its derivatives. Quantitative analysis of vanillin, ethyl vanillin, and methyl vanillin in Thai rice cultivars. GRAPHICAL ABSTRACT

Evaluating Anatomical Characteristics Associated With Leaf Rolling in Northeastern Thai Rice Cultivars During Drought by Decision Tree

Leaf rolling is a common response to drought among members of the grass family. A detailed understanding of the structural changes that occur when rice leaves roll in response to drought may assist in determining the physiological mechanisms underlying this feature and determining its potential utility in plant breeding. The anatomical characteristics of rice cultivars native to northeastern Thailand in response to drought stress were evaluated in this study. Polyethylene glycol (PEG) treatments were applied to seedlings of 28 native rice cultivars and two rice breeding cultivars for 10 d. When cultivated in drought-prone environments, the native rice cultivars had a leaf rolling index between 4 and 7, which was classified as moderate to high leaf rolling. Rice leaf anatomy exhibited profound changes in response to drought, with smaller bulliform cells (36.8%), thicker epidermis (10.98%), smaller vascular bundles (7.41%), and smaller bundle sheath cells (11.95%). Decision trees were used to explore the association between the degree of leaf rolling and anatomical traits. According to the decision tree models generated on the basis of the gain ratio, information gain, and Gini index, the epidermis, leaf thickness, and bulliform cells were the major factors of the root nodes, and the maximum accuracy of the models was 70.90%. Overall, the models indicated that rice leaves with a thin epidermis, large bulliform cells, thin leaves, and small vascular bundles are more likely to display high leaf rolling adaptations under drought stress conditions.

Inhibition potential of volatile compounds from Thai rice cultivars against acetylcholinesterase through in vitro and docking studies

The aroma intensities of rice depend on the variety and the volatile compound content. Many volatile compounds in rice have been identified for their biological activity. In this study, we investigated the biological activity and the volatile compounds content of pigmented rice and non-pigmented rice extracts. We also investigated the inhibition potential of volatile compounds including methyl vanillate, vanillin, 2-pentyl furan and guaiacol against acetylcholinesterase through in vitro and in silico studies. The results reveal that the total phenolic and total flavonoid content was closely related to the antioxidant potential of pigmented rice and non-pigmented rice extracts. The strongest inhibition potential of volatile compounds against acetylcholinesterase was obtained from methyl vanillate followed by 2-pentyl furan and vanillin. Guaiacol had the lowest inhibition potential. Docking studies also indicated that strong binding affinity was obtained from methyl vanillate followed by 2-pentyl furan, vanillin and guaiacol, respectively. The highest methyl vanillate and vanillin contents were obtained from Khao Leum Pua. The highest content of 2-pentyl furan was obtained from Khao Leum Klaeng. Interestingly, the highest inhibition potential against acetylcholinesterase was also investigated from Khao Leum Klaeng and followed by Khao Leum Pua, respectively. The results indicated that the volatile compounds including methyl vanillate, 2-pentyl furan and vanillin seem to be the key compounds for acetylcholinesterase inhibitory activity in these rice extracts. Practical applications Methyl vanillate, 2-pentyl furan and vanillin are the key compounds for acetylcholinesterase inhibitory activity of rice extracts. Our findings provided candidate compounds for application in the treatment of Alzheimer's disease (AD) and also benefit on human health.

Three rhizobacteria differentially change endogenous hormones and yield in four rice cultivars

Four Thai rice cultivars Pathum Thani 1, RD41, RD57, and RD85 were investigated to observe their responses to Plant Growth Promoting Bacteria Bacillus sp. N7 (N7), Lysinibacillus sp. N5 (N5), and Bacillus thuringiensis B20 (B20). A pot experiment with 5 plants pot−1 and four replicates was used. This study reported that the combination of plant growth promoting bacteria and optimized fertilization play role in crop yield enhancement by modulating endogenous levels of indole-3-acetic acid, salicylic acid, and tryptophan. Endogenous levels of indole-3-acetic acid, salicylic acid, tryptophan, and grain-yield-related components and grain yield of four Thai rice cultivars Pathum Thani 1, RD41, RD57, and RD85 were measured. Significant (p < 0.05) increase in grain yield observed at PTT1, RD41, and RD85 (40.13–51.18 g pot−1, 43.33–54.05 g pot−1, 47.80–69.08 g pot−1, respectively), but no significant (p > 0.05) grain yield increase in RD57 (48.75–51.75 g pot−1) when compared to uninoculated conditions. Significant (p < 0.05) endogenous indole-3-acetic acid, salicylic acid, and tryptophan level changes compared to the uninoculated control were observed across four Thai rice cultivars. Consortia development to enhance the plant growth promoting bacteria capability and larger field trials will be performed in the future to further investigate the efficacy of the bacteria in the real-field application.

Salt stress responses and SNP-based phylogenetic analysis of Thai rice cultivars.

Genetic diversity is important for developing salt-tolerant rice (Oryza sativa L.) cultivars. Certain Thai rice accessions display salt tolerance at the adult or reproductive stage, but their response to salinity at the seedling stage is unknown. In this study, a total of 10 rice cultivars/line, including eight Thai cultivars and standard salt-tolerant cultivar and susceptible line, were screened using a hydroponic system to identify salt-tolerant genotypes at the seedling stage. Different morphophysiological indicators were used to classify tolerant and susceptible genotypes. Phylogenetic analyses were performed to determine the evolutionary relationships between the cultivars. Results showed that 'Lai Mahk', 'Jao Khao', 'Luang Pratahn', and 'Ma Gawk' exhibited salt stress tolerance comparable with the standard salt-tolerance check 'Pokkali'. Whole-exome single-nucleotide polymorphism (SNP)-based phylogenetic analysis showed that the Thai rice cultivars were monophyletic and distantly related to Pokkali and IR29. Lai Mahk and Luang Pratahn were found closely related when using the whole-exome SNPs for the analysis. This is also the case for the analysis of SNPs from 164 salt-tolerance genes and transcription regulatory genes. The tolerant cultivars shared the same haplotype for 16 genes. Overall, the findings of this study identified four salt-stress-tolerant Thai rice cultivars, which could be used in rice breeding programs for salinity tolerance.

Yield, Grain Quality, and Starch Physicochemical Properties of 2 Elite Thai Rice Cultivars Grown under Varying Production Systems and Soil Characteristics.

Rice production systems and soil characteristics play a crucial role in determining its yield and grain quality. Two elite Thai rice cultivars, namely, KDML105 and RD6, were cultivated in two production systems with distinct soil characteristics, including net-house pot production and open-field production. Under open-field system, KDML105 and RD6 had greater panicle number, total grain weight, 100-grain weight, grain size, and dimension than those grown in the net-house. The amounts of reducing sugar and long amylopectin branch chains (DP 25–36) of the RD6 grains along with the amounts of long branch chains (DP 25–36 and DP ≥ 37), C-type starch granules, and average chain length of the KDML105 were substantially enhanced by the open-field cultivation. Contrastingly, the relative crystallinity of RD6 starch and the amounts of short branch chains (DP 6–12 and DP 13–24), B- and A-type granules, and median granule size of KDML105 starch were significantly suppressed. Consequently, the open-field-grown RD6 starch displayed significant changes in its gelatinization and retrogradation properties, whereas, certain retrogradation parameters and peak viscosity (PV) of KDML105 starches were differentially affected by the distinct cultivating conditions. This study demonstrated the influences of production systems and soil characteristics on the physicochemical properties of rice starches.

Bioaccessibility and antioxidant activity of phenolic acids, flavonoids, and anthocyanins of encapsulated Thai rice bran extracts during in vitro gastrointestinal digestion

Encapsulation technique was applied to improve the stability of bioactive compounds in bran extracts from Thai rice cultivars (Khao Dawk Mali 105, Kiaw Ngu, Hom Nil, and Leum Pua), using three carriers including gelatin, gum Arabic, and the mixture of gelatin and gum Arabic. The microcapsules obtained using gelatin provided a higher production yield of 76.08, 85.63, 85.63 and 85.59%, respectively. A greater encapsulation efficiency was also observed in the extracts encapsulated with gelatin (93.45, 95.91, 91.19 and 95.09%, respectively). After simulated gastric and intestinal digestion, the microcapsules formed by using gelatin exhibited the higher release of bioactive compounds and antioxidant activity than unencapsulated extracts. However, the extracts encapsulated using gelatin and gum Arabic complex yielded the lowest release of bioactive compounds and their antioxidant activity after simulated digestion. The overall results showed that gelatin was an appropriate carrier that could protect bioactive compounds from the digestion conditions.

Effects of simulated acid rain on morphological traits of Thai rice cultivars

Effects of simulated acid rain on morphological traits of Thai rice cultivars

Proteomics of Seed Nutrition-Associated Proteins in Germinated Brown Rice in Four Thai Rice Cultivars Analyzed by GeLC-MS/MS

Brown rice (BR) and germinated brown rice (GBR) of Oryza sativa L. are popularly consumed by Asians because of their important healthy diet components. They are known to contain bioactive compounds and nutrients, such as phenolics, vitamins, fatty acids, and sugars, which help to maintain good health and reduce the incidences of various chronic diseases. The objective of this study was to investigate the effects of germination on changes of nutrition-associated proteins in 4 rice cultivars. After germination for 24 h, the changes of seed nutrition-associated proteins were examined by shotgun proteomics. The total proteins from non-germinated seeds and 24 h germinated seeds of 4 rice cultivars were extracted and analyzed by in-gel digestion coupled with tandem mass spectrometry (GeLC-MS/MS). A total phenolic content was analyzed from the crude methanol extract of those grains after germination for 0, 24, and 48 h using Folin-Ciocalteu assay. The analysis showed that seed nutritional-associated proteins, especially phenolic-associated proteins, increased after germination according to the accumulation of the total phenolic content. The expressions of 6 phenolic-associated proteins, including phenylalanine ammonia-lyase, serine carboxypeptidase-like protein, isoflavone-7-O-methyltransferase, isoflavonoid glucosyltransferase, glycosyltransferase family 61 protein and UDP-glucose flavonoid 3-O-glucosyltransferase were increased by 2.20 - 15.90 folds after germination. This study provides evidence that rice germination for 24 h has essentially influenced the increased nutritional values of BR and the phenolic biosynthetic pathway.

Six Years Monitoring of the Promising Low Grain-Cd Accumulating Rice, RD15 Cultivar Grown on Cd-contaminated Paddy Soils

The experiment was conducted on the Cd-contaminated paddy field, two of Thai rice cultivars, the prevailing KDML105 and RD15 were included together with determining grain-Cd accumulation. The results had revealed that the RD15 contained Cd in grains not only lower than KDML105 but also lower than the critical level as proposed by Codex (0.4 mg kg-1 polished rice). Thus, the RD15 was selected as the promising low grain-Cd accumulating rice cultivar, and farmers were encouraged to grow this cultivar. The grains of prevailing and promising rice cultivars were annually collected for Cd analysis. After six-years monitoring, the results revealed that the average concentration of Cd in KDML105 was 0.658 mg kg-1, which exceeded the critical level. On the other hand, the average concentration observed in RD15 (0.127 mg kg-1) was lower than the critical level. The human dietary intake of Cd through rice consumption was calculated, comparing to the provisional tolerable weekly intake (PTWI) as adopted by FAO/WHO (7 ug Cd kg-1 BW per week), the PTWI of KDML105 was far exceeded the critical level. Contrary, the RD15 had the PTWI lower than the critical level. Present results indicated that, by cultivating RD15 the promising low-grain Cd cultivar, Cd intake together with health risk of human could be reduced.

Effect of extraction conditions on phenolic content, anthocyanin content and antioxidant activity of bran extracts from Thai rice cultivars

The bran of two cultivars of Thai non-glutinous rice, namely Khao dawk mali 105 (white rice) and Hom nil (purple rice); and two varieties of Thai glutinous rice, namely Kiaw Ngu (white rice) and Leum Pua (dark purple rice) were assessed regarding their compositions, total phenolic content and antioxidant activity. The aims of this research were to (1) identify the major components of the various kinds of Thai rice bran and their properties, (2) evaluate the effect of extracting solvent on the chemical compositions and antioxidant activity of extracts, and (3) optimize the appropriate extraction temperature and extraction time for obtaining high-efficiency extracts. The amounts of 3 major groups of bioactive compounds, including phenolic acids, flavonoids and anthocyanins, were investigated using high-performance liquid chromatography. The highest values of phenolic acids, flavonoids, anthocyanins, total phenolic content, and antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) assays were detected in extracts obtained using 65% (v/v) ethanol. The extraction process conducted at 60 °C for 60 min provided the highest values of bioactive compounds, total phenolic content, DPPH radical scavenging activity and FRAP.

Diversity of sporulating rice endophytic fungi associated with Thai rice cultivars (Oryza sativa L.) cultivated in Suphanburi and Chainat Provinces, Thailand

Diversity of sporulating rice endophytic fungi associated with Thai rice cultivars (Oryza sativa L.) cultivated in Suphanburi and Chainat Provinces, Thailand

Effects of Brown Rice and Germinated Brown Rice Extracts from Thai Rice Cultivars (PL2 and KDML105) on Adipogenic, Adipocytokine, and Antioxidant Genes in 3T3-L1 Adipocytes

Effects of Brown Rice and Germinated Brown Rice Extracts from Thai Rice Cultivars (PL2 and KDML105) on Adipogenic, Adipocytokine, and Antioxidant Genes in 3T3-L1 Adipocytes

Gamma-aminobutyric acid and glutamic acid contents, and the GAD activity in germinated brown rice (Oryza sativa L.): Effect of rice cultivars

The γ-aminobutyric acid (GABA) and glutamic acid (Glu) contents, and the glutamate decarboxylase (GAD) activity in brown rice (BR) and germinated BR (GBR) of the 5 Thai rice cultivars KDML105, PT1, CN1, SP1, and PL2 were investigated. BR was soaked at 35°C for 12 h and then germinated for 24 h to produce GBR. Amounts of GABA and Glu, and the GAD activity in samples were determined. The GABA content and GAD activity in GBR samples of all cultivars were increased 7–50× and 10–100× over levels in BR. The GABA content in BR had no effect on GABA accumulation in GBR. There was no trend in changes in the Glu content for different cultivars after soaking and germination. Variation in the GABA amount in GBR was due to both the GAD activity and the amount of Glu. These two parameters affected accumulation of GABA in all cultivars.

Introgression of Gene for Non-Pollen Type Thermo-Sensitive Genic Male Sterility to Thai Rice Cultivars

For the two-line hybrid rice system, pollen sterility is regulated by recessive gene that responds to temperature. The recessive gene controlling thermo-sensitive genetic male sterility (TGMS) is expressed when the plants are grown in conditions with higher or lower critical temperatures. To transfer tgms gene(s) controlling TGMS to Thai rice cultivars by backcross breeding method, a male sterile line was used as a donor parent while Thai rice cultivars ChaiNat 1, PathumThani 1, and SuphanBuri 1 were used as recurrent parents. The BC2F2 lines were developed from backcrossing and selfing. Moreover, the simple sequence repeat (SSR) markers were developed for identifying tgms gene and the linked marker was used for assisting selection in backcrossing. The identification lines were confirmed by pollen observation. The results showed the success of introgression of the tgms gene into Thai rice cultivars. These lines will be tested for combining ability and used as female parent in hybrid rice production in Thailand.

Efficiencies of Chemical Techniques for Rice Grain Freshness Analysis

Two chemical methods which are commonly used for rice grain freshness determination were investigated for their efficiencies. Method 1 is made of bromothymol blue indicator, and the principle is based on indicator's color which is changed in according to pH of the stored rice grains. Method 2 is based on peroxidase activity which deteriorates during storage of rice grains. Both methods were used for determination of fresh-aged rice index of six Thai-rice cultivars, four from non-waxy rice cultivars (KDML 105, Chai Nat 1, Chai Nat 2 and Phitsanulok 2) and two from waxy rice cultivars (San-pah-tawng and RD6). Rice samples were kept in the forms of paddy and polished rice. Fresh-aged rice indices were determined using both methods every two weeks over the storage period of 24 weeks (six months). It was found that both methods were capable of detecting fresh-aged rice indices. The color of chemical solutions changed with regards to the age of rice grains and it could be detected spectrophotometrically. Rice grains which have been kept as paddy provided more consistent results. Method 1 is recommended for industrial application as it is simple, efficient and inexpensive.

Phytochemical Content and Antioxidant Activity of Colored and Non-colored Thai Rice Cultivars

Phytochemical Content and Antioxidant Activity of Colored and Non-colored Thai Rice Cultivars

Evaluation of Thai rice cultivars with low-grain cadmium

To identify rice cultivars with low grain cadmium (Cd) levels, 42 cultivars of Thai rice (Oryza sativa L.) were cultivated in a Cd-contaminated field in the Pha Te village, Mae Sot district, Tak province, Thailand, from 2009 to 2011. Among non-glutinous and late-ripening cultivars, lower levels of Cd accumulated in the grains of RD5, RD15, and Sang Yod than in Khao Dawk Mali 105, a prevailing and popular cultivar in this area. Among glutinous and late-ripening cultivars, Khao’ Niaw Ubon 1 and Khao’ Niaw Ubon 2 accumulated lower Cd levels than a prevailing cultivar RD6. The findings suggest that human cadmium intake can be reduced by selecting low-Cd rice cultivars.

Screening Thai landrace rice for blast resistance gene Pi9, Pi36, Pigm(t) using DNA markers

Rice blast caused by the fungal pathogenMagnaporthe grisea, is one of the most devastatingdiseases in rice production worldwide. Informationon rice blast resistant gene is important for ricecultivar development. The objective of this studywas to identify rice blast disease resistant genes in203 landrace Thai rice cultivars including 40 cultivars from the South, 19 cultivars from the North,144 cultivars from the Northeast of Thailandcomprised of 45 floating rice cultivars and 99lowland rice cultivars using gene specific markersfor blast resistant gene Pi9, Pi36 and Pigm(t). Theresults showed that all 203 cultivars have at leastone blast resistant gene and 42 cultivars have all thethree blast resistant genes. The outcome of thisresearch will be very useful for development of newblast resistance elite rice cultivars in the future.

Study on Total Phenolic Contents and their Antioxidant Activities of Thai White, Red and Black Rice Bran Extracts

In this study, different brans of Thai rice cultivars which were divided into 3 groups: white color (Hom mali 105, Supan, Saohai, Hom chaiya and Hom jun), red color (3256, GS 18003, 21606, 21699 and 5718) and black color (96041-20, 96051-37, 96004-49, 96023-35 and 96065-42) were investigated their Total Phenolic Content (TPC) and antioxidant activities. The rice brans were firstly extracted using methanol. The extracts were analyzed using Folin-Ciocalteau method for total phenolic content while thiocyanate method and 1,1-diphenyl-2-picrylhydrasyl (DPPH) free radical-scavenging assay were used for antioxidant activities determination. The results indicated that the total phenolic content of white, red and black rice bran extract were in the range of 0.8931-0.9884, 1.0103-1.0494 and 1.0810-1.2239 mg gallic acid equivalent (GAE mg(-1)), respectively. With thiocyanate method, percentage inhibition were in the range of 10.15-20.68, 30.64-38.80 and 25.52-26.28 for white, red and black rice bran extract, respectively. With DPPH radical-scavenging assay, methanolic extract of 5718 showed the highest (IC50=0.0057 mg mL(-1)) while Homchaiya showed the lowest (IC50=0.2582 mg mL(-1)) activities. All of extracts showed lower activity than BHA (IC50=0.0012 mg mL(-1)). However, the antioxidant activity of all rice bran extracts indicated high antioxidant efficiency in the following order: red>black>white color rice brans. It is a promising that Thai rice bran are potential antioxidant sources.