Introgression of dwarfing allele dwarf-1 from Yellow Milo reduced grain dormancy and increased pre-harvest sprouting susceptibility in sorghum converted li

BENECH-ARNOLD ROBERTO L; RODRÍGUEZ MARÍA VERÓNICA

Tsukuba

Simposio; 15th International Symposium on Pre-Harvest Sprouting in Cereals; 2023

ISSS and NARO

Introgression of dwarfing allele dwarf-1 from Yellow Milo reducedgrain dormancy and increased pre-harvest sprouting susceptibilityin sorghum converted linesMaría Verónica Rodríguez1, and Roberto L. Benech-Arnold21 IFEVA, CONICET / Cátedra de Fisiología Vegetal, Facultad de Agronomía, Universidad de BuenosAires. Av. San Martín 4453, C1417DSE. Buenos Aires, Argentina (mvr@agro.uba.ar)2 IFEVA, CONICET / Cátedra de Cultivos Industriales, Facultad de Agronomía, Universidad de BuenosAires. Av. San Martín 4453, C1417DSE. Buenos Aires, ArgentinaAbstractGrain sorghum stands as a globally significant cereal with a rich genetic diversity. The issue of preharvest sprouting (PHS) due to grain dormancy remains underexplored. Our goal was to identify andvalidate Quantitative Trait Loci (QTL) associated with grain dormancy and PHS resistance in sorghum.Building upon previous research, we utilized a RIL population derived from a RedlanxIS9530 cross forQTL mapping. Both lines are low tannin and red-grained but otherwise have a different geneticbackground: Redlan (short stature, PHS susceptible) is derived from the Sorghum conversionprogram (SCP, Texas), and IS9530 (tall, PHS resistant) from ICRISAT. A dormancy QTL, termed qDOR-9, explained between 30-40% of phenotypic variability for Germination Index (GI) and co-localizedwith a QTL for plant height. Results support that a low dormancy allele, genetically linked to adwarfing allele (dw1), was introduced from the yellow milo background (PHS susceptible) used asdonor parent during breeding to reduce plant height in the SCP. Genotype-by-sequencing (GBS)analysis demonstrated that a chromosome fragment including dw1 plus the entire qDOR-9 wasintroduced from the yellow milo into Redlan and BTx623. Two independent QTL-NILs were obtained,carrying the IS9530 allele for the QTL while maintaining the dw1 allele in the Redlan background.Phenotyping confirmed that the IS9530 allele for qDOR-9 significantly reduced GI values comparedto Redlan, thereby validating its effect on dormancy and separating it from dw1. This confirms thatintrogression of qDOR-9 could enhance PHS tolerance without affecting plant stature, offering apromising avenue for sorghum improvement through marker assisted selection. Approaches toidentify the causative polymorphism of the QTL include the obtention of recombinants for finemapping and bioinformatics (DNA and RNA seq). This might allow to improve PHS resistance throughgene editing and will certainly add to our basic understanding of the molecular basis controlling seeddormancy.