Abstract: Root orientation, or angle, is an important component of root architecture and depth of the root system. We have determined that DRO1 and DRO1-related genes are present across diverse plant phyla and fall within the IGT gene family. DRO1, present in both Arabidopsis and peach, displayed root specific expression patterns. AtDRO1 is predominantly expressed in both the root vasculature and root tips in a distinct developmental pattern. Mutation of AtDRO1 led to more horizontal lateral root angles; over-expression of AtDRO1 under a constitutive promoter reduced lateral root angles and resulted in shoot phenotypes including upward leaf curling, shortened siliques, and narrow lateral branch angles. Over-expression of PpeDRO1 in plum (Prunus domestica) led to deeper rooting phenotypes. These data establish that DRO1-related genes serve a role in altering root architecture, providing a method for drought avoidance.

Abstract: Genetically altered eudicots that have the altered phenotype of weeping are provided. The genetically altered eudicots contain a genetic alteration that silences the expression of the WEEP gene or that results in production of non-functional WEEP protein or that results in production of a reduced amount of functional WEEP protein compared to the amount of functional WEEP protein produced by a wild-type eudicot with a non-weeping phenotype. Methods of producing such genetically altered eudicots are provided.

Abstract: The genetic basis for a recessive dwarf trait (dw) in peach (Prunus persica) was determined. Using a sequencing-based bulk-segregant mapping strategy, dw was positioned on the distal end of peach chromosome 6. At the center of the mapped locus, a SNP leading to a premature stop codon was identified within the coding region of a homolog of the Giberellic Acid (GA) receptor GID1 (GA Insensitive Dwarf 1). Silencing of GID1c in the closely related species Prunus domestica (plum) led to dwarf phenotypes with shortened internodes similar to dw/dw peaches. The degree of GID1c silencing corresponded to the degree of dwarfing. Anatomical expression studies showed that GID1c was highly expressed in all actively growing peach tissues, but more predominant in apical meristems and roots. These data establish that GID1c serves a primary role in the rapid growth and elongation of peach vegetative tissues, thus providing new methods to control tree size without impacting flower or fruit development.

Abstract: Root orientation, or angle, is an important component of root architecture and depth of the root system. We have determined that DRO1 and DRO1-related genes are present across diverse plant phyla and fall within the IGT gene family. DRO1, present in both Arabidopsis and peach, displayed root specific expression patterns. AtDRO1 is predominantly expressed in both the root vasculature and root tips in a distinct developmental pattern. Mutation of AtDRO1 led to more horizontal lateral root angles; over-expression of AtDRO1 under a constitutive promoter reduced lateral root angles and resulted in shoot phenotypes including upward leaf curling, shortened siliques, and narrow lateral branch angles. Over-expression of PpeDRO1 in plum (Prunus domestica) led to deeper rooting phenotypes. These data establish that DRO1-related genes serve a role in altering root architecture, providing a method for drought avoidance.

Abstract: Technology to optimize plant architecture is critical for future efforts to increase planting density in a wide range of crops. Little is known regarding the molecular mechanisms governing this basic plant developmental feature, particularly in fruit trees. Recently, a pair of distantly related genes called LAZY1 and TILLER ANGLE CONTROL 1 (TAC1) was shown to have opposing effects on lateral branch angle in monocots and dicots. We have characterized the LAZY1 gene in both Arabidopsis and plum (Prunus domestica) and assessed its functional relationship with TAC1. Both lazy1 and tac1:lazy1 Arabidopsis plants showed a previously unreported weeping phenotype. Transgenic plum lines silenced for LAZY1 showed horizontal branch angles, sometimes marked by rootward lateral branch growth. Our results establish that manipulation of LAZY1 gene function results in changes in tree shape and can be used to engineer fruit or ornamental trees with desired branch angles.

Abstract: The genetic basis for a recessive dwarf trait (dw) in peach (Prunus persica) was determined. Using a sequencing-based bulk-segregant mapping strategy, dw was positioned on the distal end of peach chromosome 6. At the center of the mapped locus, a SNP leading to a premature stop codon was identified within the coding region of a homolog of the Giberellic Acid (GA) receptor GID1 (GA Insensitive Dwarf 1). Silencing of GID1c in the closely related species Prunus domestica (plum) led to dwarf phenotypes with shortened internodes similar to dw/dw peaches. The degree of GID1c silencing corresponded to the degree of dwarfing. Anatomical expression studies showed that GID1c was highly expressed in all actively growing peach tissues, but more predominant in apical meristems and roots. These data establish that GID1c serves a primary role in the rapid growth and elongation of peach vegetative tissues, thus providing new methods to control tree size without impacting flower or fruit development.