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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #303228

Title: Genetic interactions underlying tree branch orientation

Author
item Hollender, Courtney
item Scorza, Ralph
item Callahan, Ann
item Tworkoski, Thomas
item Dardick, Christopher - Chris

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2014
Publication Date: 7/12/2014
Citation: Hollender, C.A., Scorza, R., Callahan, A.M., Tworkoski, T., Dardick, C.D. 2014. Genetic interactions underlying tree branch orientation [abstract]. American Society for Plant Biology. Paper No. P-12023-B.

Interpretive Summary:

Technical Abstract: Expanding our understanding of the molecular and genetic mechanisms behind branch orientation in trees both addresses a fundamental developmental phenomenon and can lead to significant impacts on tree crop agriculture and forestry. Using the p-nome (pooled genome) sequencing-based mapping approach on a peach tree population, we previously identified the gene responsible for the pillar or columnar growth habit in which axillary shoots have very narrow branch angles and grow vertically as a homologue of the TAC1 (Tillar Angle Control 1) gene from rice. LAZY1, a related ancestral gene, exhibits an opposite mutant phenotype in rice, maize, and Arabidopsis, having wide tiller or branch angles. Published studies show LAZY1 has a role in both shoot gravitropism and auxin localization. We believe that TAC1 works with LAZY1 to regulate branch angles in plants. We found there is a genetic interaction between TAC1 and LAZY1. Arabidopsis tac1; lazy1 double mutants exhibit lazy phenotype, demonstrating that LAZY1 is epistatic to TAC1. We’ve performed RNAseq analysis on both Arabidopsis and peach tree mutants that suggests that TAC1 and LAZY1 functions may involve secondary metabolites. The role of TAC1 in branch orientation is not limited simply to branch angle determination. TAC1 is epistatic to the gene responsible for the weeping branch phenotype (in which branches start out with a typical branch angle eventually turn and grow downwards). Peach trees homozygous for both the tac1 null mutation and the weeping locus exhibit the pillar phenotype rather than the weeping phenotype. Using the p-nome sequence-based mapping combined with RNA-seq analysis, we have identified the putative gene responsible for the weeping branch phenotype. Additionally, preliminary gene expression profiles of peach pillar, weeping, and the double tac1; weep mutants shed light on their roles in branch orientation.