Natural variation MeMYB108 associated with tolerance to stress-induced leaf abscission linked to enhanced protection against reactive oxygen species in cassava.

ABSTRACT

KEY MESSAGE Natural variation of the MeMYB108 exon was associated with reactive oxygen scavengers led to alleviate leaf abscission under drought in cassava. The reactive oxygen scavengers play important roles in regulating the cassava (Manihot esculenta Crantz) leaf abscission induced by stresses. To date, the relationship between natural variations of MYB genes and reactive oxygen scavengers under drought in cassava genotypes remains unclear. Here, we reported the transcription factor MeMYB108 played an important role in regulating leaf abscission exposed to drought in cassava. The expression levels of MeMYB108 in abscission zones of cassava leaf pulvinus were higher in cassava genotype SC124, which were less easy to shed leaves under stress than cassava genotype SC8 when the leaf abscission induced by the same drought condition. Compared with wild type and interference expression plants, overexpression of MeMYB108 significantly reduced the drought-induced leaf abscission rate under drought. The consecutively 2-year analysis of reactive oxygen scavengers showed significant differences among different cassava genotypes under drought-induced leaf abscission, indicating the relevance between reactive oxygen scavengers and leaf abscission. Correlation analysis revealed the natural variation of the MeMYB108 exon was associated with reactive oxygen scavengers during drought-induced leaf abscission. Association analysis between pairwise LD of DNA polymorphism indicated the MeMYB108 allele enhanced the tolerance of cassava to drought-induced leaf abscission. Complementation transgenic lines containing the elite allele of MeMYB108 SC124 decreased the leaf abscission rate induced by drought conditions, demonstrating natural variation in MeMYB108 contributed to leaf abscission tolerance induced by drought in cassava. Further studies showed MeMYB108 played an active role in the tolerance of cassava to drought-induced leaf abscission by inducing scavenging of reactive oxygen species.