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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 #273112
Title: Identification of PpTAC1 as a regulator of lateral bud growth angle in peach

Author
item Dardick, Christopher - Chris
item Callahan, Ann
item ZHEBENTYAYEVA, TATYANA - Clemson University
item ABBOTT, ALBERT - Clemson University
item HORN, RENATE - University Of Rostock
item Scorza, Ralph

Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2013
Publication Date: 6/13/2013
Citation: Dardick, C.D., Callahan, A.M., Zhebentyayeva, T., Abbott, A., Horn, R., Scorza, R. 2013. Identification of PpTAC1 as a regulator of lateral bud growth angle in peach. Science. DOI:10.1111/tpj.12234.

Interpretive Summary: The use of trees for agricultural production, whether for fruit, nuts, or lumber, requires extensive land space and use of chemicals; this is mostly because of their large size and spreading growth habits. The ability to genetically alter trees to be more compact such that they can be planted closer together would increase productivity and reduce costs associated with land space and chemicals. Here, we report the identification of a gene that controls the growth angle of branches in peach trees. When this gene is disrupted, the tree branches grow more vertically producing a pillar or columnar shape. We also show this same effect in the model plant Arabidopsis thaliana. Surprisingly, this same gene was found to perform a very similar function in more distantly related rice and corn. The knowledge gained from this work should shed light on how early plants first adapted to life on land and provide technologies for manipulating plant architecture to improve productivity.

Technical Abstract: The adaptation of early plants to terrestrial environments required the development of gravity sensing or gravitropism. Gravitropism plays a significant role in the directional growth of primary and secondary meristems in both roots and shoots. Rather than growing parallel to the gravity vector, axillary meristems typically grow more perpendicular; thus, allowing plants to spread out. Here, we report the identification of a gene (Br) in peach associated with parallel axillary branch angles producing a non-spreading or “pillar” phenotype. To identify Br, we sequenced and assembled pooled genomes (dubbed pnomes) derived from individuals segregating for the pillar or wild-type traits, and compared polymorphism frequencies to simultaneously generate a map position and identify candidate genes. A single insertion event unique to pillar individuals was identified within the 3rd exon of a gene encoding a hypothetical protein. Expression studies showed that Br is expressed in branch and flower pedicel attachment sites in wild-type but not pillar trees. Sequence comparisons identified the Br gene as the peach orthologue of rice TAC1 (Tiller Angle Control 1) which negatively influences gravitropic responses in both rice and corn. Arabidopsis lines containing a T-DNA insertion within AtTAC1 also showed narrow axillary branch angles in reproductive bolts. Iterative BLAST searches identified PpTAC1 as a member of a novel gene family (named IGT) present in all available plant genomes including mosses. Among these were homologues of the LAZY1 gene from rice which is known to positively regulate gravitropism. The finding that TAC1 controls both tiller angle in monocots and axillary branch angle in dicots, and that family members are present in primitive plants suggests that IGT genes likely contributed to the development of gravitropism in terrestrial plants.