The male gametophyte of the semi-aquatic fern, Marsilea vestita, produces multiciliated spermatozoids in a rapid developmental sequence that is controlled post-transcriptionally when dry microspores are placed in water. Development can be divided into two phases, mitosis and differentiation. During the mitotic phase, a series of nine successive division cycles produce 7 sterile cells and 32 spermatids in 4.5-5 h. During the next 5-6 h, each spermatid differentiates into a corkscrew-shaped motile spermatozoid with ∼140 cilia. In order to study the mechanisms that regulate spermatogenesis, we used RNAseq to generate a reference transcriptome that allowed us to assess abundance of transcripts at different stages of development. Here, we characterize transcripts present in the kinesin motor family. Over 120 kinesin-like sequences were identified in our transcriptome that represent 56 unique kinesin transcripts. Members of the kinesin-2, -4, -5, -7, -8, -9, -12, -13, and -14 families, in addition to several plant specific and 'orphan' kinesins are present. Most (91%) of these kinesin transcripts change in abundance throughout gametophyte development, with 52% of kinesin mRNAs enriched during the mitotic phase and 39% enriched during differentiation. Functional analyses of six kinesins with different patterns of transcript abundance show that the temporal regulation of these transcripts during gametogenesis correlates directly with kinesin protein function.
Keywords: armadillo repeat kinesin; ciliogenesis; kinesin-13; kinesin-14; kinesin-4; kinesin-‘orphan’ III; mitosis.
© 2016 Wiley Periodicals, Inc.