Biosensor for Cassava Brown Streak Virus (CBSD) with CRISPR-Cas13a SECTION 1: ABSTRACT Cassava is a plant cultivated annually and widely grown across the subtropical and tropical regions of the world and seen as an important food crop as a souce of carbohydrate for more than 800 million people globally. It is seen as drought resistant, and growm in low nutrient soils. It is cultivated in an area more than 22 million hectares in Africa and Asia. There are yield losses that are experienced due to biotic and abiotic challenges from poor agronomic practices,pest and diseases. Cassava brown streak disease (CBSD) leads to total yield losses in the susceptible varieties by destroying the edible roots while the rest of the plant looks healthy. It is seen as one of the most dangerous threat to cassava production in East, Central and some parts of Southern Africa. Since it is an assymptomatic disease, a cheap and quick way to detect is needed with minimum false positives in detection. CRISPR/Cas13a based detection system
will be used to detect CBSD in plant samples. The sensing of the system will be on recombinase polymerase amplification and Cas13a-mediated collateral cleavage activity. The positive reception can be distinguished after 20 min by a significantly enhanced fluorescence signal. When compared to other detection methods, the sensitivity of CRISPR/Cas13a-based detection system is found that the detection system has limits of detection that reaches 2.26 × 10 2 copies/µl and a 10-fold increase compared with the sensitivity of using RT-PCR to detect the virus. Furthermore, the CRISPR/Cas13a-based detection system has a high selectivity for the CBSD without interference from other viruses. The CRISPR/Cas13a-based detection system can be used to sense the CBSD in samples of cassava leaves.