RNA interference cassette
The modified cassava contains an RNA interference (RNAi) cassette designed to target African cassava mosaic virus replication associated gene (AC1) and capsid protein (AV1). Transcription is initiated from the Cauliflower mosaic virus (CaMV) 35S promoter and terminates at the CaMV 35S terminator. The transcript contains two segments (sense and antisense) of AC1 separated by a plant synthetic intron. The sense AC1 sequence is preceded by an AV1 antisense sequence and the antisense AC1 is followed by a sense AV1 sequence. Post-transcription, the intron functions as a loop and allows the sense and antisense segments of AC1 and AV1 to base pair, forming hairpin RNA (hpRNA). The hpRNA acts as double stranded RNA (dsRNA), which triggers an RNAi response and the host cell machinery will target AC1 and AV1 viral transcripts for degradation.

Note:
- The segment of AC1 corresponds to position 1690 to 1844 of the ACMV DNA 1 (DNA A) (GenBank accession AJ427910).
- The segment of AV1 corresponds to position 492 to 647 of the ACMV DNA 1 (DNA A) (GenBank accession AJ427910).
- The source of the AC1 and AV1 sequences is ACMV strain Nigeria-Ogo.
- Due to the RNAi response, no protein is expected to be translated from the RNAi cassette.

Selectable marker
Transcription of Escherichia coli hygromycin B phosphotransferase is under transcriptional control of the CaMV 35S promoter and terminator.
RNA interference
An RNAi response is an anti-viral response triggered by the recognition of dsRNA. Host DICER recognizes dsRNA, cleaving the dsRNA into small interfering RNA (siRNA), roughly 21-23 bp long (size is host dependent). The siRNA is then bound by ARGONAUTE family proteins, which unwind the duplex, leaving a single strand of the siRNA and activating the RISC complex. The RISC complex targets transcripts with homology to the siRNA and degrades them.