Genetic engineering of sorghum with Fe deficiency-tolerant genes enhances iron uptake, phytosiderophore secretion, and stress resilience, improving growth in alkaline soils.
Keywords: Bioengineering, Calcareous soil, Energy plant, Iron deficiency tolerance, Rice, Sorghum bicolor
Iron (Fe) deficiency is a critical issue limiting the cultivation of crops, especially in alkaline soils where Fe is nearly water-insoluble. Plants require Fe as a cofactor for enzymes and electron carriers,however, in high-pH soils like alkaline soils, Fe’s near insolubility restricts its availability, causing chlorosis, reduced photosynthesis, and yield loss. Sorghum, a vital cereal crop, exhibits limited Fe uptake and secretion of mugineic acid family phytosiderophores (MAs), compounds essential for Fe acquisition in graminaceous plants. Scientists from Ishikawa Prefectural University and The University of Tokyo, as well as colleagues from other institutions, investigated the sorghum genome in an effort to identify genes for iron uptake and translocation with the goal to ultimately develop sorghum with increased tolerance to Fe deficiency. The researchers demonstrated that sorghum’s Fe acquisition genes show conserved mechanisms linked to specific genes in rice and barley. However, sorghum produces lower amounts of MAs, a bottleneck in its Fe uptake strategy. Introducing Fe deficiency-tolerant genes from barley and rice into sorghum, including IDS3 for MA synthesis, HvNAS1 for precursor production, and OsIRO2 to enhance Fe uptake responses, has shown promise in improving Fe deficiency tolerance. Transgenic sorghum lines with these genes demonstrated increased chlorophyll, MA secretion, and Fe accumulation under Fe-limited conditions.
Additionally, the introduction of ferric-chelate reductase activity, combined with transcription factors responsive to Fe deficiency, further strengthened sorghum’s ability to thrive in calcareous soils. These advancements are complemented by similar advancements in rice, where enhanced MA secretion and dual Fe uptake strategies have proven effective under fluctuating water conditions. Future bioengineering efforts aim to integrate multiple traits, such as improved Fe and Zn accumulation in seeds, enhanced drought tolerance, and stress resilience, to boost crop productivity in Fe-limited environments. This research emphasizes the potential of genetic modifications in addressing agricultural challenges posed by nutrient deficiencies.
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Reference:
Senoura T, Nozoye T, Yuki R, Yamamoto M, Maeda K, Sato-Izawa K, Ezura H, Itai RN, Bashir K, Masuda H, Kobayashi T, Nakanishi H, Nishizawa NK. Molecular-based characterization and bioengineering of Sorghum bicolor to enhance iron deficiency tolerance in iron-limiting calcareous soils. Plant Mol Biol. 2024 Oct 24;114(6):117. PMID: 39448407. doi: 10.1007/s11103-024-01508-y. Read more