Levels of MeLEA3, a cDNA Sequence Coding for an Atypical Late Embryogenesis Abundant Protein in Cassava, Increase Under In Vitro Salt Stress Treatment

Cassava (Manihot esculenta Crantz) is a tropical food crop that is well adapted to critical climate and soil conditions, including drought, one of the most serious abiotic stresses that limit crop production in agriculture. Expression of late embryogenesis abundant (LEA) proteins is involved in acquisition of tolerance to drought, cold and high salinity in many different organisms. Here, we report on the characterization of a cassava MeLEA3 cDNA sequence and its deduced amino acid sequence. MeLEA3 protein was deduced from a full-length cDNA sequence of 664 bp with a 285-bp open reading frame, consisting of 94 amino acid residues, with a calculated molecular weight of 10 kDa and a theoretical isoelectric point of 9.66. The most abundant amino acid found in MeLEA3 protein was alanine (18.09%), followed by lysine (9.57%) and serine (9.57%). A search for conserved domain revealed that MeLEA3 belongs to Pfam family LEA3, PF03242. Furthermore, Kyte-Doolittle algorithm and MitoProt II software analyses showed that MeLEA3 is a hydrophobic atypical LEA protein predicted to be exported to mitochondria. In addition, semi-quantitative RT-PCR assays showed that accumulation of MeLEA3 transcripts is increased in leaves treated with sodium chloride, indicating a potential role in salt stress response. Our results also revealed no introns within the MeLEA3 genomic sequence. This is the first study on characterization of a LEA sequence in cassava that can contribute to understanding molecular mechanisms involved in resistance of this crop to abiotic stresses.