The invention discloses a preparation method and application of a biological herbicide based on an
RNA (Ribonucleic Acid) interference technology, which specifically comprises the following steps: designing a specific siRNA (Small Interference Ribonucleic Acid) sequence through a targeted
glutamine synthetase
gene (GS2),
cloning a reverse repeat structure of the specific siRNA sequence to multiple
cloning sites of an L4440 vector, and transforming the reverse repeat structure to RNase III defective
escherichia coli HT115 for induced
fermentation. By optimizing IPTG concentration and
induction time, the thalli efficiently express target dsRNA, and a dsRNA
aqueous solution is prepared after splitting
decomposition and purification. Foliage spraying is adopted during spraying treatment, dsRNA can permeate into
plant cells through pores, GS2 mRNA is specifically degraded,
ammonium ions in the cells are accumulated, a photosynthetic
system collapses, and leaves wither, wither and yellow and finally die within 72 hours. Compared with a traditional chemical herbicide, the herbicide has the advantages of being accurate in targeting, safe,
environmentally friendly, free of residues and the like, and an efficient and sustainable biological solution is provided for agricultural weeding.