Genetic dissection of plant architecture and life history traits salient to climate-resilient sustainable intensification of agricul ture
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Multiple-harvest ratooning or perennial crops have recently regained recognition with increased projected demand for food and fuel accompanied by anticipated world population growth, and decline of arable land due to soil erosion, nutrient leaching and decreasing organic matter. The genus Sorghum is especially attractive to study perenniality and related traits, being an important source of food, feed and fuel; a weakly ratooning plant at tropical and sub-tropical regions; and with the possibility to cross with two perennial relatives. We developed a series of sorghum populations to study perenniality and life history related traits using forward genetics. Notably, two novel tetraploid backcross populations (BC1F1) developed by interspecific crosses derived from Sorghum bicolor × S. halepense displayed rich transgressive variation for some life history traits. Patterns of gene transmission have been characterized by constructing genetic maps and resolving segregation patterns. A single nucleotide polymorphism (SNP) profile among S. halepense and its progenitors, S. bicolor and S. propinquum, has elucidated the evolutionary history of S. halepense with deduction of its genomic composition from its progenitors and from mutation. Quantitative trait studies have discovered important chromosomal regions responsible for agronomically important and perenniality related traits, enriching knowledge of quantitative trait loci (QTL) in sorghum. Comparison of S. halepense derived QTLs to those in two other sorghum populations and to those on paleo-duplicated chromosomal regions provide early insight into the extent of genetic novelty that may have been associated with the evolution of polyploid S. halepense following 96 million years of abstinence from polyploidy in the sorghum lineage.