Enhancement of grain number per spike by RNA interference of cytokinin oxidase 2 gene in bread wheat.

Background: This study aimed to validate the function of CKX gene on grain numbers in wheat.

Methods: we constructed and transformed a RNA interference expression vector of TaCKX2.4 in bread wheat line NB1. Southern blotting analysis was used to select transgenic plants with single copy. The expression of TaCKX2.4 gene was estimated by Quantitative real-time PCR (qRT-PCR) analysis. Finally, the relation between expression of TaCKX2.4 gene and grain numbers was validated.

Results: Totally, 20 positive independent events were obtained. Homozygous lines from 5 events with a single copy of transformed gene each were selected to evaluate the expression of TaCKX2.4 and grain numbers per spike in T3 generation. Compared with the control NB1, the average grain numbers per spike significantly increased by 12.6%, 8.3%, 6.5% and 5.8% in the T3 lines JW39-3A, JW1-2B, JW1-1A and JW5-1A, respectively.

Conclusion: Our study indicated that the expression level of TaCKX2.4 was negatively correlated with the grain number per spike, indicating that the reduced expression of TaCKX2.4 increased grain numbers per spike in wheat.