Location: Cereal Crops ResearchTitle: Antagonistic regulation of auxiliary bud outgrowth by the BRANCHED genes in tobacco
|DING, NA - University Of Kentucky|
|QIN, QIULIN - University Of Kentucky|
|WU, XIA - University Of Kentucky|
|MILLER, ROBERT - University Of Kentucky|
|ZAITLIN, DAVID - University Of Kentucky|
|LI, DANDAN - University Of Kentucky|
Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2020
Publication Date: 3/2/2020
Citation: Ding, N., Qin, Q., Wu, X., Miller, R., Zaitlin, D., Li, D., Yang, S. 2020. Antagonistic regulation of auxiliary bud outgrowth by the BRANCHED genes in tobacco. Plant Molecular Biology. https://doi.org/10.1007/s11103-020-00983-3.
Interpretive Summary: The shoots that result from outgrowth of axillary buds in tobacco, commonly called suckers, seriously compromise leaf yield and quality. Although the growth of axillary buds can be inhibited by application of sucker control chemicals, the chemical residues are of increasing concern. Therefore, genetic control of sucker growth in tobacco is needed. In the present study, we functionally characterized and validated five BRANCHED genes that are involved in the regulation of axillary bud outgrowth. We show that the BRANCHED genes contribute opposing regulatory roles in lateral branching. Our study provides new perspectives for the genetic control of sucker outgrowth using the BRANCHED genes in tobacco.
Technical Abstract: As a key signaling integrator of shoot branching, BRANCHED 1 (BRC1) coordinates and is orchestrated by endogenous and environmental signals involved in the regulation of axillary bud outgrowth. Functional analysis of BRC1 and its homolog BRC2 suggests that lateral branching is suppressed by BRC1 and that neo-functionalization of the BRC1 genes may have occurred by gene duplication, specialization, or selective purification. Using CRISPR site-directed mutagenesis and overexpression assays, we characterized the regulatory roles of five BRC gene members in tobacco. We show that lateral branching is negatively regulated by NtBRC1A-1, 1B-1, and 1B-2, but was unexpectedly promoted by NtBRC2A. The NtBRC1A-2 gene seems not to be required for the regulation of axillary bud outgrowth. Suppression of bud growth may be attained by direct binding of NtBRC proteins to Tassels Replace Upper Ears 1 (TRU1) genes, as evidenced by RNAi and CRISPR-mediated gene editing. The BRC2 gene, which is thought to be unnecessary for branch development, probably confers a dominant negative effect by interfering with the branching-inhibitory BRC1 genes. However, the molecular mechanism of NtBRC2A action still needs to be further addressed. Our results may indicate that there is a blind spot when using genetic tools, such as CRISPR and RNAi, in the functional characterization of members of a gene family.