TaCol-B5 is a gene discovered in CItr 17600, a spring wheat line developed by the International Maize & Wheat Improvement Center.
Zhang et al. (1) crossed CItr 17600 with Yagmai18, a spring cultivar widely used in the Yangtze River region of China and searched for spikelets node per spike (SNS) QTLs in an F2:3 mapping population. A major QTL on chromosome arm 7BL was significantly associated with higher SNS (LOD value 15.3). It was derived from CItr 17600 and showed dominant effects, accounting for 43% of the variability observed in the field test. Besides the effect of SNS, it was also positively associated with spike length. The QTL was designated QSns.osu-7B.
Using a positional cloning approach Zhang et al. (1) determined that TraesCS7B02G400600 is the most likely gene responsible for QSns.osu-7B. TraesCS7B02G400600 encodes a CONSTANS-like protein and is orthologous to the COL5 gene of other plant species. The wheat gene was designated TaCol-B5. To validate their findings, they produced transgenic Yangmai18 lines carrying the cDNA of TaCol-B5. These lines showed a modified architecture and more spikelets per spike. Some environmental and plant-density effects were observed on grain number. Nonetheless, the net effect of the TaCol-B5 transgene on grain yield was positive.
The allele of Yagmai18, Tacol-B5, showed three amino acid substitutions compared to the TaCol-B5 favorable allele from CItr 17600. A screening of a global panel of 1657 accessions with this marker showed that TaCol-B5 is relatively rare (2%) in the modern wheat germplasm.
CAPS Marker for TaCol-B5
Zhang et al. (1) developed a diagnostic CAPS marker based on one of differential amino acid substitutions between TaCol-B5 and Tacol-B5.
TaCOL-B5F1 5’-ACAGCGTTAGTCGCCTCGT -3’
PCR and digestion conditions
- Denaturing step: 94 °C for 5 min
- Amplification step:
94°C for 3 mins
40 cycles of 94°c for 30s
60°C for 30s, and 72°C for 30s
5% DMSO was added to the PCR reaction
- Extension step: &2°C for 5 mins
- Digestion: with Pfl-MI restriction enzyme, overnight at 37°C
After Pfl-MI digestion of the PCR product a fragment of 543 bp was observed for TaCol-B5 (CItr 17600) and two bands (302 bp and 241 bp) for Tacol-B5. On the "M" labelled lane a 500-bp band is shown.
1. TaCol-B5 modifies spike architecture and enhances grain yield in wheat. Zhang X, Jia H, Li T, Wu J, Nagarajan R, Lei L, Powers C, Kan CC, Hua W, Liu Z, Chen C. In: Science, 2022, 376(6589):180-3. DOI:10.1126/science.abm0717.