Method for generating resistance against citrus diseases caused by insects, fungi, oomycetes, bacteria or nematodes

A method for reducing d-limonene in citrus fruit, comprising:

• genetically transforming a plant of a Citrus spp., by introducing a transgene encoding at least an antisense RNA having a sequence corresponding to a d-limonene synthase gene configured to trigger RNA silencing of at least an endogenous messenger RNA encoding a polypeptide with d-limonene synthase activity, to thereby induce a Citrus spp. plant defense response, reduce the d-limonene synthase activity, and reduce accumulation of endogenous d-limonene by at least 50 fold and cause an increase in non-d-limonene terpenoids as compared to a wildtype plant of the same Citrus spp.;
• and
• performing an assay to determine whether a Citrus spp. plant defense response is induced.

A method for reducing d-limonene in citrus fruit, comprising:

• genetically transforming a plant of a Citrus spp., by introducing a transgene encoding a constitutively expressed RNA having at least one antisense RNA portion configured to trigger RNA silencing of at least an endogenous messenger RNA encoding a polypeptide with d-limonene synthase activity, to thereby reduce the d-limonene synthase activity, reduce accumulation of endogenous d-limonene by at least 50 fold and increase accumulation of non-d-limonene terpenoids as compared to a wildtype plant of the same Citrus spp.;
• and
• performing at least one assay to determine that the reduction in d-limonene synthase activity is sufficient to induce a Citrus spp. plant defense response in the plant.