Detection of basmati rice using microsatellite markers

Basmati rice is a fine and aromatic rice grown mainly in certain areas of Punjab province in Pakistan. It has high demand in the international market and a source of earning foreign exchange via export. Adulteration of non-basmati rice grains is a major challenge to secure its export standards. Hence, the development of a simple and cost-effective method is necessary to screen the basmati and non-basmati rice samples. In this study, we have validated the efficiency of different molecular markers by screening seven unknown rice samples. Our results demonstrated that three markers namely RM1, RM19 and RM225 proved to be efficient microsatellite molecular markers that could be used to screen basmati and non-basmati rice samples. Further, these results are validated based on expression pattern of Badh2 gene among the basmati and non-basmati rice. Thus, this study provides a contribution towards development of a simple and cost-effective method for rapid screening of basmati rice.

Starch Morphology and Metabolomic Analyses Reveal That the Effect of High Temperature on Cooked Rice Elongation and Expansion Varied in Indica and Japonica Rice Cultivars

Rice (Oryza sativa L.) is mainly grouped into indica and japonica varieties. The aim of this study was to investigate the effect of temperature on cooked rice elongation, cooked rice expansion, and rice fragrance. This study was conducted in three growth temperature chambers with indica cultivar Basmati 385 (B385) and japonica cultivar Yunjingyou (YJY). Grains of B385 grown in low-temperature regimes had the highest cooked rice elongation and expansion, whereas the grains of YJY grown in high-temperature regimes had the highest cooked rice elongation and expansion. Starch granules of B385 grown in low-temperature regimes were more compact and bigger, compared to grains grown in medium- and high-temperature regimes. Conversely, the starch granules of YJY grown in high-temperature regimes were more compact and bigger, compared to those grown in medium- and low-temperature regimes. Metabolomic analyses showed that temperature affected the rice metabolome and revealed that cyclohexanol could be responsible for the differences observed in cooked rice elongation and expansion percentage. However, in both B385 and YJY, grains from low-temperature regimes had the highest 2-AP content and the lowest expression levels of the badh2 gene. The findings of this study will be useful to rice breeders and producers.

The Determination of Aromatic Character of Several Local Rice Varieties using Phenotypic Analysis and Molecular DNA

The pandan scent in aromatic rice has been known as the result of 8 bp deletions and 3 Single Nucleotide Polymorphisms (SNPS) in BADH2 gene, which produce non-functional betaine aldehyde dehydrogenase (BADH) enzyme. Several DNA markers for aromatic character based on mutation in BADH2 gene have been developed. In our experiment, we analysed the presence of aromatic character in four local rice variety such as Merah Wangi, Pendok, Genjah Arum, and Mentik Wangi Susu using KOH method and DNA molecular method using three DNA markers to detect mutation that responsible for the development of aromatic character. Phenotype analysis using KOH method showed that Merah Wangi, Genjah Arum, and Mentik Wangi Susu produce pandan scents. PCR analysis using Bradbury and Badex7-5, and RM223 markers showed the presence of BADH2 mutation in Merah Wangi and Mentik Wangi Susu, whereas Pendok and Genjah Arum did not show BADH2 mutation using those used three markers. Our results indicate that among four investigated local rice, only Merah Wangi and Mentik Wangi Susu are categorized as aromatic rice whereas Pendok and Genjah Arum are non-aromatic.Keywords: genetic analysis, aromatic rice, specific markers, genetic mutation.

Allelic variations in aroma gene in cultivated rice varieties

Germplasm is a valuable source of genetic diversity that supports crop improvement efforts in any breeding programme but it must first be fully characterised for economically valuable traits before it can be effectively utilised. In rice (Oryza sativa), the development of new varieties with improved aroma requires correct phenotyping and prior knowledge of the available genes and alleles governing the aroma trait in the gene pool. Correct phenotyping and genotyping can be achieved using sensory methods and functional markers associated with polymorphisms that define the aroma genes. The objective of this study was to evaluate the aroma status of rice accessions and to assess for the various alleles of badh2 gene using functional markers. A total of 56 rice accessions were evaluated at National Crops Resources Research Institute (NaCRRI) in Uganda for their aroma using sensory methods and a molecular marker to differentiate between aromatic and non- aromatic accessions. The aromatic accessions were then evaluated for variations within the betaine aldehyde dehydrogenase2 (badh2) gene responsible for aroma in rice using functional markers. Sensory evaluation of aroma identified 23 accessions to be aromatic; while 33 were non-aromatic. Molecular results identified 20 accessions as aromatic; while 36 accessions were non-aromatic. Functional marker analysis indicated the presence of badh2-E7 allele in 20 aromatic accessions within this collection that could be employed in the breeding programme for the rice aromatic trait. Key words: badh2 alleles, functional markers, Oryza sativa

Grain Quality and Allelic Variation of the Badh2 Gene in Thai Fragrant Rice Landraces

Fragrance, which plays an important role in determining the economic value of rice to growers and consumers, is known to be controlled by the Badh2 gene. This study evaluated the grain quality characteristics and allelic variation of the Badh2 gene in 22 fragrant rice landraces from Thailand. The rice seed samples from farmers’ storage facilities in northern, northeastern and southern Thailand, plus two advanced breeding lines and three check varieties, were evaluated for seed morphology and grain quality, and their Badh2 genes covering intron 4 to intron 8 were re-sequenced. Almost all of the landraces were classified as large grain types, with medium to high gelatinization temperatures. The variation in the Badh2 gene by haplotype analysis correlated with grain aroma by sensory evaluation. The badh2-E7 was found in haplotype 1 with a strong aroma in KH, NDLP, and PLD, as in KDML105 and the moderately aromatic BNM-CMU, BNM4, and SKH, along with PTT1. Three haplotypes had different positions of SNP on the Badh2 gene with varying results in the sensory test. The present results suggest that some rice varieties could be potentially introduced as genetic resources for fragrant rice breeding programs or could be developed to highly palatable cultivars with geographical indications to increase the income of highland farmers.

Screening of traditional scented rice (Joha) of Assam for presence of Badh2, blast and brown spot diseases

The traditional scented rice (Joha) varieties are very popular among the people of Assam. The traditional scented rice though carries a premium price throughout the world, is a low yielder. However, the traditional Joha varieties are tolerant to many disease and pest, indicating the joha germplasm may be a source for several disease/pest resistant genes. However not much work has been carried out to identify the factors responsible for disease/pest tolerance in these lines. Hence, an attempt was made in 39 Joha germplasms to identify blast and brown spot resistant/tolerant germplasms at Regional Agricultural Research Station, Assam Agricultural University, Titabar. In most of the aromatic lines the aroma is due to the function of the Badh2 gene. Therefore, an attempt was made to study the action of Badh2 gene in these germplasms with the help of SNP analysis. The present study reveals the associated between Badh2 gene fragrance in most of the Joha germplasms. However in some aromatic Joha germplasms the fragrance is not correlated with the action of Badh2, and it may be due to some other factors. This finding needs further studies to identify the factors contributing to the fragrance in Joha rice.

Isolation and Molecular Marker Detection of Badh2 Gene from Aromatic Rice Germplasm Resources in Southern Henan

The production of aroma in aromatic rice is due to the increase of 2-acetyl-1-pyrroline (2-AP) precursor substances caused by the functional deletion of Badh2 gene on chromosome 8, and the accumulation of 2AP makes rice produce aroma. In this study, Badh2 gene was isolated and cloned from 18 representative aromatic rice cultivars in Southern Henan, and the bioinformatics analysis of Badh2 gene was carried out. Meanwhile, seven functional molecular markers developed by Badh2 gene were used to detect and analyze Badh2 gene in 18 aromatic rice varieties from Southern Henan. The results showed that the coding region of Badh2 gene was 1509 bp in length. It contained 15 exons and 14 introns, and encoded 503 amino acids. There are many types of variation of the Badh2 gene in the 18 aromatic rice varieties. According to the variation of Badh2 gene, the tested aromatic rice varieties could be divided into three groups, among which Xinxianggeng 1, Xiangnuo 25, Heixiangdao 193 and Xiangbao 2 were concentrated in group Ⅰ, while the other 14 kinds of aromatic rice were concentrated in group II. Seven functional molecular markers of Badh2 gene were used to detect different varieties mutation types in exon 2, exon 4~5, exon 7 and exon 13 of Badh2 gene. No aromatic rice varieties with different mutation types were found in promoter region, exon 12 and exon 14 of Badh2 gene. Therefore, our results provide important information for understanding the genetic basis of fragrant genes in aromatic rice germplasm resources in Southern Henan and breeding new varieties of high-quality aromatic rice using molecular marker-assisted selection.