The evolution of photoperiod-insensitive flowering in sorghum, a genomic model for panicoid grasses

Cuevas, H E and Zhou, C and Tang, H and Khadke, P P and Das, S and Lin, Y R and Ge, Z and Clemente, T and Upadhyaya, H D and Hash, C T and Paterson, A W (2016) The evolution of photoperiod-insensitive flowering in sorghum, a genomic model for panicoid grasses. Molecular Biology and Evolution, 33 (09). pp. 2417-2428. ISSN 0737-4038

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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. x S. bicolor (L.) Moench], revealed a quantitative trait locus, 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 million years ago 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 x 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.

Item Type: Article
Divisions: RP-Dryland Cereals
CRP: CGIAR Research Program on Dryland Cereals
Uncontrolled Keywords: Flowering, Sorghum, Genomic model, Panicoid grass, Genetic regulation
Subjects: Mandate crops > Sorghum
Others > Genetics and Genomics
Depositing User: Mr Ramesh K
Date Deposited: 29 Jul 2016 09:34
Last Modified: 05 Jan 2017 15:57
URI: http://oar.icrisat.org/id/eprint/9598
Official URL: http://dx.doi.org/10.1093/molbev/msw120
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: The late K. F. Schertz was instrumental in the early stages of this work. This work was supported by the US Department of Agriculture National Research Initiative Competitive Grants Program (00-35300-9215), the United Sorghum Checkoff Program (R0001-10), the Sun Grant Program and the USDA Biotechnology Risk Assessment Grants (BRAG) program (95-33120-1935, 2012- 01658).
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