Natural variations of MeMYB2 in cassava varieties covering a wide range of the reactive oxygen scavenging enzymes under drought

Abstract

Background Cassava ( Manihot esculenta Crantz) is an important tropical crop with excellent stress tolerance and stress resistance genes. The antioxidant enzymes play an important role in regulating the cassava plants respond to stress. To date, little is known the relationship between natural variations of MYB genes that have been proven to regulate stress tolerance in model plants and the diversity of reactive oxygen scavenging enzymes under drought in cassava varieties. Therefore, we conducted this study to discover natural variations in MYB2 gene in association with the reactive oxygen scavenging enzymes. Results Here, the relationship between the natural variation of MYB2 gene and the reactive oxygen scavenging enzymes under drought in cassava were analyzed. Natural variation of antioxidant enzymes in leaf and roots of 97 cassava varieties under drought analyses indicated that the variation of the various antioxidant enzymes is very different among the cassava varieties. MeMYB2 expression profiling analysis indicated that MeMYB2 was up-regulated obviously when induced by drought stress. Re-sequencing analysis of the 97 cassava varieties indicated that the MeMYB2 gene region included 87 single nucleotide variants (SNPs) and two insertion/deletion variants (Insert/ Deletion, Indel), the SNP locus of the coding region of MeMYB2 gene can be divided into 29 haplotypes, including 7 major haplotypes. These 7 major haplotypes can be classified into two categories, one of which is more closely related to wild cassava genotype W14, which indicates that MeMYB2 is positively selected during cassava breeding. Correlation analysis between MeMYB2 and drought tolerance showed that 12 functional SNPs in the MeMYB2 coding region were significantly associated with CAT activity, proline content, SOD activity and other traits, and the prediction of interaction with key genes of drought tolerance was further confirmed that MeMYB2 and key genes involved in CAT, proline and SOD can interact through intermediate metabolic pathways. Conclusions Some natural variations exist in the MeMYB2 , which might be involved in regulating the reactive oxygen scavenging enzymes (SOD and CAT) changes under stress. This study will facilitate the understanding of the roles of MYB s in regulating the reactive oxygen scavenging enzymes.