Abstract: The present invention relates to a novel method of inserting viral DNA, which optionally may contain cargo-DNA, into plants or viable parts thereof, but preferably into plants of the monocotyledon class, and most preferably into plants of the family Gramineae, using suitable transfer microorganisms. Further comprised by the invention are recombinant DNA, plasmid and vector molecules suitably adapted to the specific conditions of the process according to the invention and the transgenic plant products obtainable in accordance with the said process.

Abstract: Yellows diseases have devastated crops, particularly of citrus fruit. They are associated with (and ostensibly caused by) very small mycoplasma or spiroplasma type organisms (MLO for short). Attempts at chemical control of MLOs have been unsuccessful. The present invention is based on a remarkable new finding that biological control can be achieved by introducing into the phloem of the plant a virus which is infective to the MLO. The invention is of particular interest in relation to diseases associated with Spiroplasma citri, especially in citrus plantations.