Browsing by Author "Griffiths, Howard"

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GWAS identifies genetic loci underlying nitrogen responsiveness in the climate resilient C4 model Setaria italica (L.)
(Elsevier B.V., 2022) Bandyopadhyay, Tirthankar; Swarbreck, Stéphanie M; Jaiswal, Vandana; Maurya, Jyoti; Gupta, Rajeev; Bentley, Alison R.; Griffiths, Howard; Prasad, Manoj
Introduction N responsiveness is the capacity to perceive and induce morpho-physiological adaptation to external and internal Nitrogen (N). Crop productivity is propelled by N fertilizer and requires the breeding/selection of cultivars with intrinsically high N responsiveness. This trait has many advantages in being more meaningful in commercial/environmental context, facilitating in-season N management and not being inversely correlated with N availability over processes regulating NUE. Current lack of its understanding at the physio-genetic basis is an impediment to select for cultivars with a predictably high N response. Objectives To dissect physio-genetic basis of N responsiveness in 142 diverse population of foxtail millet, Setaria italica (L.) by employing contrasting N fertilizer nutrition regimes. Methods We phenotyped S. italica accessions for major yield related traits under low (N10, N25) and optimal (N100) growth conditions and genotyped them to subsequently perform a genome-wide association study to identify genetic loci associated with nitrogen responsiveness trait. Groups of accessions showing contrasting trait performance and allelic forms of specific linked genetic loci (showing haplotypes) were further accessed for N dependent transcript abundances of their proximal genes. Results Our study show that N dependent yield rise in S. italica is driven by grain number whose responsiveness to N availability is genetically underlined. We identify 22 unique SNP loci strongly associated with this trait out of which six exhibit haplotypes and consistent allelic variation between lines with contrasting N dependent grain number response and panicle architectures. Furthermore, differential transcript abundances of specific genes proximally linked to these SNPs in same lines is indicative of their N dependence in a genotype specific manner. Conclusion The study demonstrates the value/ potential of N responsiveness as a selection trait and identifies key genetic components underlying the trait in S. italica. This has major implications for improving crop N sustainability and food security.
Identifying the mechanistic basis to nitrogen responsiveness in two contrasting Setaria italica accessions
(Oxford University Press, 2024) Bandyopadhyay, Tirthankar; Maurya, Jyoti; Bentley, Alison R; Griffiths, Howard; Swarbreck, Stéphanie M; Prasad, Manoj
Nitrogen (N) is a macronutrient limiting crop productivity with varied requirements across species and genotypes. Understanding the mechanistic basis of N responsiveness by comparing contrasting genotypes could inform the development and selection of varieties with lower N demands, or inform agronomic practices to sustain yields with lower N inputs. Given the established role of millets in ensuring climate-resilient food and nutrition security, we investigated the physiological and genetic basis of nitrogen responsiveness in foxtail millet (Setaria italica L.). We had previously identified genotypic variants linked to N responsiveness, and here, we dissect the mechanistic basis of the trait by examining the physiological and molecular behaviour of N responsive (NRp-SI58) and non-responsive (NNRp-SI114) accessions at high and low N. Under high N, NRp-SI58 allocates significantly more biomass to nodes, internodes and roots, more N to developing grains, and is more effective at remobilising flag leaf N compared to NNRp-SI114. Post anthesis flag leaf gene expression suggests that differences in N induce much higher transcript abundance in NNRp-SI114 than NRp-SI58, a large proportion of which are potentially regulated by APETALA2 (AP2) transcription factors. Overall, the study provides novel insights into the regulation and manipulation of N responsiveness in S. italica.