CsTFL1 inhibits determinate growth through interaction with CsNOT2 and CsFDP in cucumber (Cucumis sativus L.)

Authors: WEN, CHANGLONG - Beijing Academy Of Agricultural Sciences; ZHAO, WENSHENG - China Agriculture University; LIU, WEILUN - China Agriculture University; YANG, LUMING - University Of Wisconsin; WANG, YUHUI - University Of Wisconsin; LIU, XINGWANG - China Agriculture University; XU, YONG - Beijing Academy Of Agricultural Sciences; REN, HUAZHONG - China Agriculture University; GUO, YANGDONG - China Agriculture University; LI, GONG - China Agriculture University; LI, JIGANG - China Agriculture University; Weng, Yiqun; ZHANG, XIAOLAN - China Agriculture University

Submitted to: Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2019
Publication Date: 7/29/2019
Citation: Wen, C., Zhao, W., Liu, W., Yang, L., Wang, Y., Liu, X., Xu, Y., Ren, H., Guo, Y., Li, G., Li, J., Weng, Y., Zhang, X. 2019. CsTFL1 inhibits determinate growth through interaction with CsNOT2 and CsFDP in cucumber (Cucumis sativus L.). Development. 146(14):1-12. https://doi.org/10.1242/dev.180166.
DOI: https://doi.org/10.1242/dev.180166

Interpretive Summary: Background information: Cucumber is an important vegetable crop. Open-field and greenhouse cucumber production requires different plant architecture: indeterminate growth is favorable for protected environments; determinate growth is better pickling cucumber in the once-over mechanical harvest system. However, the genetic basis of determinacy is largely unknown in cucumber. Findings: In this study, we cloned the (de) gene for determinate growth habit in cucumber, and found that a mutation (SNP) in the CsTFL1 (TERMINAL FLOWER1) gene of indeterminate plants will result in determinate growth. We studied the functions of this gene through various approaches including its spatial-temporal expression patterns in cucumber. We also identified other genes in cucumber that interact with CsTFL1 to control determinate growth. Why is it important? Findings from this study identified the genetic/molecular mechanisms in cucumber to regulate determinate/indeterminate growth. Such knowledge may provide a strategy for fine tuning plant architecture using the CsTFL1 gene to adapt to different cucumber production systems. Who cares? Plant geneticist have interests in understanding molecular mechanisms of determinate/indeterminate growth in cucumber. This work provides an important target gene for plant breeders to manipulate plant architecture in cucumber breeding.

Technical Abstract: 1. Cucumber is an important vegetable crop that carries on vegetative growth and reproductive growth simultaneously. Indeterminate growth is favorable for fresh market under protected environments, while determinate growth is preferred for pickling cucumber in the once-over mechanical harvest system. The genetic basis of determinacy is largely unknown in cucumber. 2. In this study, map-based cloning of the de (determinate) locus showed that the determinate growth habit is caused by a non-synonymous SNP in CsTFL1, a homolog of the Arabidopsis TERMINAL FLOWER 1 (TFL1). Molecular biology, developmental biology and biochemical methods were combined to explore the biological function of CsTFL1 in cucumber. 3. Comparative phylogenetic analyses revealed that TFL1 homologous genes among cucumber, melon and watermelon shared unique features in the coding sequence as well as regulatory regions. CsTFL1 is expressed in the subapical regions of the shoot apical meristem, lateral meristem and young stems. Ectopic expression of CsTFL1 rescued the terminal flower phenotype in the Arabidopsis tfl1-11 mutant and delayed flowering in wild type Arabidopsis. Knockdown of CsTFL1 by RNAi resulted in determinate growth and formation of terminal flowers in cucumber. Biochemical analyses indicated that CsTFL1 interacts with a homolog of miRNA biogenesis gene Negative on TATA less2 (CsNOT2a); CsNOT2a interacts with FD PARALOG (FDP). Cucumber FLOWERING LOCUS T (CsFT) directly interacts with CsNOT2a and CsFD, and CsFD interacts with two 14-3-3 proteins. No interactions were detected between CsTFL1 and CsFD or CsFT. 4. These data suggested that CsTFL1 competes with CsFT for interaction with CsNOT2a-CsFDP to inhibit determinate growth and terminal flower formation in cucumber. Thus, our work suggests a strategy for fine tuning plant architecture using CsTFL1 to adapt to different cucumber production systems.