RESUMO
Graminaceous plants secrete hydroxylated phytosiderophores encoded by the genes iron-deficiency-specific clone 2 (Ids2) and iron-deficiency-specific clone 3 (Ids3). An effort was made to identify a putative ortholog of Hodeum vulgare Ids3 gene in hexaploid wheat. The protein structure of TaIDS3 was modeled using homology modeling and structural behavior of modeled structure was analyzed at 20 ns. The simulation trajectory using molecular dynamics simulation suggested the model to be stable with no large fluctuations in residues and local domain level RMSF values (< 2.4 Å). In addition, the ProFunc results also predict the functional similarity between the proteins of HvIDS3 and its wheat ortholog (TaIDS3). The TaIds3 gene was assigned to the telomeric region of chromosome arm 7AS which supports the results obtained through bioinformatics analysis. The relative expression analysis of TaIds3 indicated that the detectable expression of TaIds3 is induced after 5th day of Fe starvation and increases gradually up to 15th day, and thereafter, it decreases until 35th day of Fe-starvation. This reflects that Fe deficiency directly regulates the induction of TaIds3 in the roots of hexaploid wheat. The identification of HvIds3-like gene in wheat has opened up new opportunities to enhance the nutrient quality in wheat through biofortification program.
RESUMO
High molecular weight glutenin subunits (HMWGS) are responsible for dough elasticity and bread making quality of bread wheat. Related wild non-progenitor species, Aegilops kotschyi possesses higher molecular weight x and y glutenin subunits than the bread wheat cultivars. A wheat-Aegilops substitution line with 1U chromosome was used for the transfer of (HMWGS) of 1U to wheat by using pollen radiation hybridization approach. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiling showed different patterns of allelic variations with either the presence or absence of HMWGS, Glu-1A (1, null), Glu-1B (7, 7 + 8, 17 + 18) and Glu-1D (5 + 10, 2 + 12, null). The pollen irradiated wheat-Aegilops derivatives, B-56-1-4-2, B-56-1-4-3, B-14-1 and B-14-2 with Glu1Ux and 1Uy and absence or presence of some Glu-1A and Glu-1B HMWGS showed high micro SDS sedimentation test (MST) values while B-16-1 and B-16-2 had moderate MST values and high protein content. However, B-58-3 with transfer of Glu-1Ux + 1Uy for Glu-1D showed very low MST values indicating that Glu-1Ux + 1Uy enhance MST value only in the presence of Glu1D HMWGS. The transfer/substitution of alien HMW-GS for Glu-1A and or Glu-1B loci only can lead to improved bread making quality of wheat.
RESUMO
PURPOSE: To transfer the 2S chromosomal fragment(s) of Aegilops kotschyi (2S(k)) into the bread wheat genome which could lead to the biofortification of wheat with high grain iron and zinc content. MATERIALS AND METHODS: Wheat-Ae. kotschyi 2A/2S(k) substitution lines with high grain iron and zinc content were used to transfer the gene/loci for high grain Fe and Zn content into wheat using seed irradiation approach. RESULTS: Bread wheat plants derived from 40 krad-irradiated seeds showed the presence of univalents and multivalents during meiotic metaphase-I. Genomic in situ hybridization analysis of seed irradiation hybrid F2 seedlings showed several terminal and interstitial signals indicated the introgression of Ae. kotschyi chromosome segments. This proves the efficacy of seed radiation hybrid approach in gene transfer experiments. All the radiation-treated hybrid plants with high grain Fe and Zn content were analyzed with wheat group 2 chromosome-specific polymorphic simple sequence repeat markers to identify the introgression of small alien chromosome fragment(s). CONCLUSION: Radiation-induced hybrids showed more than 65% increase in grain iron and 54% increase in Zn contents with better harvest index than the elite wheat cultivar WL711 indicating effective and compensating translocations of 2S(k) fragments into wheat genome.