Genome-wide characterization and expression analysis of α-amylase and β-amylase genes underlying drought tolerance in cassava

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Background Starch hydrolysates are energy sources for plant growth and development, regulate osmotic pressure and transmit signals in response to biological and abiotic stresses. α-amylase (AMY) and β-amylase (BAM) are important enzymes that catalyze the hydrolysis of plant starch. Cassava (Manihot esculenta Crantz) is treated as one of the most drought-tolerant crops, however, mechanisms how AMY and BAM response to drought in cassava are still unknown. Results Six MeAMY genes and ten MeBAM genes were identified and characterized in the cassava genome. Both MeAMY and MeBAM gene families contain four genes with alternative splicing. Tandem and fragment replications play an important role in the amplification of MeAMY and MeBAM genes. Both MeBAM5 and MeBAM10 have a BZR1/BES1 domain at the N-terminus, which may have transcription factor functions. The promoter regions of MeAMY and MeBAM genes contain a large number of cis-acting elements related to abiotic stress, and MeAMY1, MeAMY2 and MeBAM3 are proved as key genes in response to drought stress according to their expression patterns under drought. The starch content, soluble sugar content, and amylase activity in cassava significantly altered under different levels of drought stress. Conclusions These results could provide fundamental knowledge for further investigation of the function of starch metabolism under drought stress in cassava, offering new perspectives for understanding the underlying mechanism for its ability to survive and produce under drought.