The Evolution of Photoperiod-Insensitive Flowering in Sorghum, A Genomic Model for Panicoid Grasses
Journal
Molecular Biology and Evolution
Journal Volume
33
Journal Issue
9
Start Page
2417
End Page
2428
Date Issued
2016-09-01
Author(s)
Cuevas, Hugo E.
Zhou, Chengbo
Tang, Haibao
Khadke, Prashant P.
Das, Sayan
Ge, Zhengxiang
Clemente, Thomas
Upadhyaya, Hari D.
Hash, C. Thomas
Paterson, Andrew H.
Abstract
Of central importance in adapting plants of tropical origin to temperate cultivation has been selection of daylength-neutral genotypes that flower early in the temperate summer and take full advantage of its long days. A cross between tropical and temperate sorghums [Sorghum propinquum (Kunth) Hitchc.×S. bicolor (L.) Moench], revealed a quantitative trait locus (QTL), FlrAvgD1, accounting for 85.7% of variation in flowering time under long days. Fine-scale genetic mapping placed FlrAvgD1 on chromosome 6 within the physically largest centiMorgan in the genome. Forward genetic data from "converted" sorghums validated the QTL. Association genetic evidence from a diversity panel delineated the QTL to a 10-kb interval containing only one annotated gene, Sb06g012260, that was shown by reverse genetics to complement a recessive allele. Sb06g012260 (SbFT12) contains a phosphatidylethanolamine-binding (PEBP) protein domain characteristic of members of the "FT" family of flowering genes acting as a floral suppressor. Sb06g012260 appears to have evolved ∼40 Ma in a panicoid ancestor after divergence from oryzoid and pooid lineages. A species-specific Sb06g012260 mutation may have contributed to spread to temperate regions by S. halepense ("Johnsongrass"), one of the world's most widespread invasives. Alternative alleles for another family member, Sb02g029725 (SbFT6), mapping near another flowering QTL, also showed highly significant association with photoperiod response index (P = 1.53×10 (-) (6)). The evolution of Sb06g012260 adds to evidence that single gene duplicates play large roles in important environmental adaptations. Increased knowledge of Sb06g012260 opens new doors to improvement of sorghum and other grain and cellulosic biomass crops.
Subjects
conversion
flowering
FT domain
Photoperiod
single gene duplication
Sorghum halepense ("Johnsongrass")
Type
journal article