A desiccation-induced transcript in lily (Lilium longiflorum) pollen

This work characterizes a desiccation and abscisic acid (ABA)-induced transcript, designated LLP-B3, present in pollen of Lilium longiflorum during development and stress. The LLP-B3 cDNA encodes a gene product having a sequence of 160 amino acids, a calculated molecular mass of 17.8 kDa, and a pI of 4.3. The polypeptide is mainly hydrophilic having a stretch of hydrophobic region at the N-terminus, indicating the presence of a signal peptide. The expression of LLP-B3 gene is pollen-specific, and the transcript accumulates only at the stage of pollen maturation. Premature drying of developing pollen indicated that the accumulation of LLP-B3 transcripts was associated with desiccation. Treatment of pollen with abscisic acid resulted in the accumulation of LLP-B3 mRNA during germination. Sequence analysis demonstrates similarities between the predicted lily LLP-B3 protein and a corn Zmc13, a tomato LAT52, an arabidopsis leaf SAH7 and a group of major allergens including Ole e 1 of olive tree. Southern blots of lily genomic DNA indicate that LLP-B3 is a single or low copy number gene. The function of the desiccation-associated protein is discussed.