Two hundred and seventy wheat varieties developed in India during the past 100 years were assessed for allelic diversity of waxy genes and two hundred varieties for starch pasting properties. Large variation was exhibited in starch pasting properties such as peak viscosity (159.3 to 303.2 RVU), RVA breakdown (28.5 RVU to 111.4 RVU), setback (73.2 to 116.3) and final viscosity (109.2 to 309.1 RVU) measured by Rapid Visco-Analyzer. Flour swelling power varied from 10.25 to 16.19 with the average value of 13.24. Final viscosity showed strong positive correlation with peak viscosity (R2 = 0.55). Significant positive correlation was observed between peak viscosity and flour swelling power (R2 = 0.37). Because flour swelling can be measured using 40 mg of the flour, it has utility in breeding programme to identify desirable recombinants in early segregating generations. Polymerase chain reaction (PCR) amplification of Wx-B1 locus showed the presence of Wx-B1 null in 60% of the varieties and exhibited significant positive correlation with peak viscosity (P < 0.01), flour swelling power (P < 0.001) and RVA breakdown (P < 0.001). Therefore, the combination of both the PCR for Wx-B1 null and microlevel test for starch properties such as FSP can be used for the improvement of flour properties suitable for various end-use products of wheat.
A full length phytase (TaPAPhy_a1.1) gene was cloned and sequenced from Indian wheat cultivar DBW17. The 2,060 bp sequence has four introns of 63, 90, 94, 103 bp and encodes a polypeptide of 548 amino acids. N-terminal residues 5 to 19 contain a signaling peptide (SP) targeted to the vacuole. The predicted molecular weight and isoelectric point were 60.53 kDa and 6.74, respectively. A phylogenetic tree analysis revealed that TaPAPhy_a1.1 clustered on a branch with PAPhy_a1 from Aegilops tauschii cultivar NGB 9855. A structural model of TaPAPhy_a1.1 protein showed a single chain dimer containing two metal ions (Fe and Zn) bound at its active site. It belongs to the metallophosphoesterase group containing a characteristic set of seven amino acid residues (Asp, Asp, Tyr, Asn, His, His, His) involved in metal ligation. The full length TaPAPhy_a1.1 gene sequence from this investigation can be used for allele mining studies to identify superior alleles for higher phytase levels for improving the nutritional quality of wheat.
Two hundred and forty diverse set of wheat cultivars released in India during the last several decades were evaluated for HMW and LMW glutenin alleles, for assessing their diversity and effect on sedimentation volume and mixograph parameters. Both SDS-PAGE and PCR based markers were employed in identifying alleles encoded at Glu-1 and Glu-3 loci. Extensive allelic variation was observed at both the Glu-1 and Glu-3 loci. There was prevalence of Glu-A1b, Glu-B1i, Glu-D1a, Glu-A3c, Glu-B3b, Glu-B3g and Glu-D3b. The alleles Glu-A1b, Glu-B1i, Glu-D1d, Glu-A3b, Glu-B3g/h and Glu-D3b exhibited high SDS-sedimentation volume. Glu-B1i and Glu-D1d showed highly significant positive effect (p < 0.001) on sedimentation volume and also had additive effects. However, surprisingly overall there was decline in the frequency of Glu-B1i allele during last two decades in Indian wheat breeding and not a single 1B/1R translocation cultivar possessed this allele. Glu-A1b showed significant positive effect on mixograph peak time, peak slope and peak width. Glu-B3g exhibited significantly higher mixograph peak time and width at 8 and Glu-B3h showed higher dough stability. Glu-B3j (1B/1R translocation) exhibited highest peak slope indicating the negative effect on dough strength. This information can be useful in designing breeding program for the improvement of Indian bread wheat quality.
In the present investigation, expression of genes related to Na+ exclusion such as salt overly sensitive (TaSOS1) and Na+/H+ antiporter (TaNHX1) and proline accumulation such as pyrroline-5-carboxylate reductase (P5CR) and glutamate synthase (GOGAT) was studied in seedlings of Kharchia 65 (Kh 65, salt tolerant) and HD 2009 (sensitive) under salt stress (ECe, 12 dSm–1) and controlled conditions. As compared to HD 2009, Kh 65 showed significantly lower accumulation of Na+ (p < 0.01) and higher accumulation of proline (p < 0.05) in leaf blade under salt stress. The relative expression of TaSOS1 increased significantly (p < 0.001) in roots of Kh 65 (4.31-fold) while it decreased in HD 2009. There was significantly higher (p < 0.01) relative expression of TaNHX1 (27.57-fold) in leaf and 3.07-fold in roots of Kh 65 as compared to 3.65- and 0.87-fold increase in leaf and roots of HD 2009, respectively, under salt stress. There was significantly (p < 0.05) higher accumulation of proline as compared to HD 2009 in leaf tissues. There was significantly higher (p < 0.01) expression of P5CR (5.23-fold in leaf and 8.77-fold in the root) and glutamate synthase (6.0- fold in roots) in Kh 65 as compared to HD 2009. The study demonstrated that upregulation of genes for Na+ exclusion in root and compartmentation in leaf and increased proline concentration are associated with tolerance to salinity stress in wheat. The information will be useful for improving wheat genotypes for salt tolerance.
Authors:R. Ponnuswamy, A. Rathore, A. Vemula, R.R. Das, A.K. Singh, D. Balakrishnan, H.S. Arremsetty, R.B. Vemuri and T. Ram
The All India Coordinated Rice Improvement Project of ICAR-Indian Institute of Rice Research, Hyderabad organizes multi-location testing of elite lines and hybrids to test and identify new rice cultivars for the release of commercial cultivation in India. Data obtained from Initial Hybrid Rice Trials of three years were utilized to understand the genotype × environment interaction (GEI) patterns among the test locations of five different agro-ecological regions of India using GGE and AMMI biplot analysis. The combined analysis of variance and AMMI ANOVA for a yield of rice hybrids were highly significant for GEI. The GGE biplots first two PC explained 54.71%, 51.54% and 59.95% of total G + GEI variation during 2010, 2011 and 2012, respectively, whereas AMMI biplot PC1 and PC2 explained 46.62% in 2010, 36.07% in 2011 and 38.33% in 2012 of the total GEI variation. Crossover interactions, i.e. genotype rank changes across locations were observed. GGE biplot identified hybrids, viz. PAN1919, TNRH193, DRH005, VRH639, 26P29, Signet5051, KPH385, VRH667, NIPH101, SPH497, RH664 Plus and TNRH222 as stable rice hybrids. The discriminative locations identified in different test years were Coimbatore, Maruteru, VNR, Jammu, Raipur, Ludhiana, Karjat and Dabhoi. The AMMI1 biplot identified the adaptable rice hybrids viz., CNRH102, DRH005, NK6303, NK6320, DRRH78, NIPH101, Signet5050, BPH115, Bio452, NPSH2003, and DRRH83. The present study demonstrated that AMMI and GGE biplots analyses were successful in assessing genotype by environment interaction in hybrid rice trials and aided in the identification of stable and adaptable rice hybrids with higher mean and stable yields.