Discovering the genetic blueprint for designing drought-adapted crops

Albert Chern Sun Wong, Ian D Godwin, Erik J van Oosterom, Andrew K Borrell
2021 Zenodo  
Stay-green is a valuable trait in crop breeding that enables plants to delay senescence during grain-filling under post-anthesis drought stress. In sorghum, expression of stay-green is a consequence of regulation of the water supply and demand framework through modulation of plant canopy and root architecture. However, the underlying molecular mechanisms regulating stay-green remain elusive. Several quantitative trait loci (QTL) and fine-mapping studies have identified members of the PIN-FORMED
more » ... (PIN) family of auxin efflux carriers as potential candidates that can modulate plant architecture to express the stay-green phenotype. SbPIN1, SbPIN2 and SbPIN4 have been identified as key candidates within the stay-green QTLs of Stg3b, Stg2 and Stg1, respectively. Gene expression and physiological studies have demonstrated that SbPIN1, SbPIN2 and SbPIN4 were expressed in a tissue-specific manner during early tillering and floral initiation, while overexpressing SbPIN1, SbPIN2 and SbPIN4 individually with their native promoters conferred distinct physiological changes, both above- and below-ground. The overexpression (OE) of SbPIN2 and SbPIN4 has greater impacts relative to SbPIN1 on influencing tillering, leaf size, leaf vein density, photosynthesis, panicle architecture, nodal root numbers and root biomass. Interestingly, a case study using CRISPR/Cas9 demonstrated the knockdown of SbPIN1 and SbPIN4 significantly increased leaf size without changing tillering and other canopy and root traits. Transcriptome studies suggested that Stg1 introgression influenced auxin and cytokinin homeostasis, whereas genes in monolignol biosynthesis were upregulated. Introgression of Stg2 had minimal impact on global gene expression during floral initiation. Transcriptome profiles of SbPIN1, SbPIN2 and SbPIN4 OE transgenics revealed putative ge [...]
doi:10.5281/zenodo.7277030 fatcat:xqyaktr6u5ca7fr66kyggdql7y