Abstract: One pair of degenerated primers was designed based on the conserved domain of resistance gene Xa21，which had LRR-liked domain and came from rice. The genome DNA of cassava germplasm E1340 and GR911 was extracted and used as template，which was resistant and susceptible to cassava bacterial blight separately. Two products of about 0.5 kb were obtained by PCR reaction. These two products were purified，cloned and sequenced， and then the same sequences of 474 nt were got. This sequence was highly matched with the homology segment anchored on the genome of cassava germplasm AM560. The long segment including each about 2.2 kb sequences from upstream and downstream of the homology segment was obtained，then one gene was predicted and named SLR1. Sequence analysis results of SLR1 showed that the ORF included 1 641 nucleotides encoding 546 amino acids. This predicted protein was higher consistent with senescence-associated protein reported，may play an important role in senescence mechanism of cassava.