This study aimed to enhance the Inpari 42 rice variety by integrating the aromatic trait through Marker-Assisted Backcrossing (MAB) while improving key agronomic characteristics in the BC₁F₁ generation. The aromatic gene from Merah Wangi was successfully introgressed into BC₁F₁ plants, confirmed through molecular analysis using the Bradbury marker, which detects mutations in the BADH2 gene responsible for fragrance in rice. Thirty BC₁F₁ plants with a heterozygous mutation in BADH2 were identified, demonstrating the reliability of MAB in maintaining the aromatic trait across generations. Agronomic evaluations revealed that BC₁F₁ plants exhibited intermediate flowering time, increased plant height, and longer panicles compared to the parental lines. Additionally, BC₁F₁ plants showed enhanced tillering capacity, more productive tillers, and higher grain yield per plant, indicating the successful integration of desirable traits from both parents. The next step in this research is to conduct further backcrosses with Inpari 42 to develop a stable aromatic variety, combining the high-yielding characteristics of Inpari 42 with the aromatic traits of Merah Wangi. These findings highlight the potential of BC₁F₁ lines for developing high-yielding aromatic rice varieties suitable for diverse agricultural settings.

Fragrance is considered one of the most highly valued grain quality traits in rice, yet its genetic basis among Philippine cultivars, especially traditional accessions, is unknown. This study characterized the fragrance gene Betaine aldehyde dehydrogenase isoform 2 (BADH2) in selected Philippine aromatic rice cultivars at the DNA, transcript, and phenotypic level. DNA fragment length analysis showed that eight out of 18 cultivars were positive for badh2.1, an allele responsible for the accumulation of 2-acetyl-1-pyrroline (2AP), the marker compound for fragrance in rice. DNA sequence alignment of nine cultivars confirmed the absence of 8 base pairs (bp) and three single nucleotide polymorphism (SNPs) in exon 7 in Dinorado White, Saigorot, and Salanay, while revealing several other nucleotide variations in other coding regions and immediate upstream region of the gene. The BADH2 gene expression profile showed that aromatic cultivars have varying lower amounts of the BADH2 mRNA than the non-aromatic cultivars. Results in 2AP analysis showed significant discrepancies in 2AP levels among cultivars during wet and dry season, which may be due to some possible factors such as sequence variation in the coding regions of BADH2, affecting gene expression, and environmental factors such as exposure to stress or postharvest processes. Overall, results have shown that aroma production among the Philippine aromatic cultivars was not due to just one genetic mechanism. Further investigation regarding analysis at the protein level, characterization of regulatory mechanisms in gene expression, and finding new genes that may be involved in the production of aroma must be pursued.

Citations

Citations to this article as recorded by  

• Variability in 2-acetyl-1-pyrroline production and associated mutations in BADH2 gene in aromatic rice cultivars of Bangladesh
  Mahmuda Umme Rayhan, Habibul Bari Shozib, Fardous Mohammad Safiul Azam, Tofazzal Islam
  Gene Reports.2023; 33: 101847.     CrossRef