Baruah, A.R.Debnath, Neelakshi2022-02-262022-02-262018-08https://krishikosh.egranth.ac.in/handle/1/5810182942The development of super rice to break the yield plateau is one of the goals for rice breeding in recent years. Ideal plant architecture (IPA), which is under polygenic control, has been proposed as means to enhance rice yield potential. A study directed towards assessing the presence of desired alleles for IPA related genes/quantitative trait loci (QTL) in rice cultivars grown in diverse agroecological situations, specifically the aromatic rice of Assam (joha rice) that usually bears weaker plant type should be of prime importance. The present study was conducted to detect allelic variation for IPA in traditional, high yielding and joha rice cultivars of Assam and to compare nucleotide sequence variation for aroma gene in cultivars possessing IPA. A total of 80 cultivars comprising sali, ahu, boro and joha rice of Assam were assessed for markers linked to five IPA related QTLs (Sol1, PAY1, IPA1, Gn1 and LAZY1). Although a total of 15 markers (M3, M6, M8, M10 for Sol1; RM339, RM223, SP5, SP7 for PAY1; RM149, RM1345, M4, M5 for IPA1; PD56, M265 for LAZY1; 16BPDEL for Gn1) were employed to check for polymorphism, only five markers (GN1, M10, M265, RM 1345, SP5) showed reproducible and polymorphic results. The Gn1 and Sol1 were most abundant in cultivars as evident from the observation that 46 numbers of cultivars harboured desired alleles for Gn1 and Sol1 followed by PAY1( 31 cultivars), LAZY1 (12 cultivars) and IPA1(12 cultivars). Among HYVs, the varieties such as Ranjit, Mahsuri and Bahadur were found to possess four numbers of desired alleles, however, IPA1 allele was other than the expected. Among Joha cultivars, Bengoli joha, Goalporia joha, Kartica joha were with the maximum of four numbers of positive alleles. As Ranjit missed the expected size of the IPA1 allele, differential expression for the gene in Ranjit and one cultivar possessing the desired IPA1 allele (Chakaw Poireton) was conducted. It revealed that although Ranjit did not possess the desired IPA1, however, the expression pattern revealed that 25-30 fold more accumulation of transcripts for the gene in Ranjit than Chakaw Poireton, suggesting the functional differences in the coding regions. The allele specific analysis for aroma gene, badh2 revealed that the markers could efficiently group 53.66% of the cultivars corresponding to the existing phenotype, indicating the power of the marker to be utilized in a large germplasm screening for aroma. The sequencing for badh2.hapG9 detected a non-synonymous substitution (AG) which was not being reported elsewhere; however, novelty of which needed to be confirmed and validated. The study will enhance our knowledge to formulate breeding strategies for combing IPA with aroma.EnglishThesis