Abstract: Provided are methods for enhancing plant cell disease resistance, comprising (1) generating a homozygous gene modification of AtSR1 (or AtSR1 ortholog or homolog) in a plant or plant cell characterized by sialic acid-mediated systemic acquired resistance (SA-mediated SAR), wherein said gene modification reduces or eliminates the calmodulin-binding activity of the respective AtSR1 or AtSR1 ortholog or homolog; or (2) expression of a recombinant or mutant AtSR1 sequence (or AtSR1 gene ortholog or homolog sequence) encoding a modified AtSR1, or AtSR1 ortholog or homolog protein, in a plant or plant cell, wherein said protein modification reduces or eliminates the calmodulin-binding activity of the respective AtSR1 or AtSR1 ortholog or homolog protein. Plants and/or plant cells comprising said modified AtSR1, or AtSR1 ortholog or homolog proteins, and/or said expression means (e.g.

Abstract: Provided are methods for enhancing plant cell disease resistance, comprising (1) generating a homozygous gene modification of AtSR1 (or AtSR1 ortholog or homolog) in a plant or plant cell characterized by sialic acid-mediated systemic acquired resistance (SA-mediated SAR), wherein said gene modification reduces or eliminates the calmodulin-binding activity of the respective AtSR1 or AtSR1 ortholog or homolog; or (2) expression of a recombinant or mutant AtSR1 sequence (or AtSR1 gene ortholog or homolog sequence) encoding a modified AtSR1, or AtSR1 ortholog or homolog protein, in a plant or plant cell, wherein said protein modification reduces or eliminates the calmodulin-binding activity of the respective AtSR1 or AtSR1 ortholog or homolog protein. Plants and/or plant cells comprising said modified AtSR1, or AtSR1 ortholog or homolog proteins, and/or said expression means (e.g.

Abstract: Particular aspects show that DWF1 is a Ca2+/calmodulin-binding protein, and this binding is critical for function. Molecular/genetic analysis using site-directed and deletion mutants revealed that loss of calmodulin binding abolished the function of DWF1 in planta, whereas partial loss of calmodulin binding resulted in a partial dwarf phenotype in complementation studies, providing direct proof that Ca2+/calmodulin-mediated signalling has a critical role in controlling the DWF1 function. Furthermore, DWF1 orthologues from other plants have a similar Ca2+/calmodulin-binding domain, indicating that Ca2+/calmodulin regulation of DWF1 and its homologues is common, and broadly applicable in plants. Methods for generating size-engineered crops are provided by altering the Ca2+/calmodulin-binding property of their DWF1 orthologues.