Unusual core histones specifically expressed in male gametic cells of Lilium longiflorum

Abstract

We have cloned three novel histone genes using antibodies that recognize only nuclei of the male gametic (generative and sperm) cells of Lilium longiflorum. The deduced amino acid sequence of each clone shows only between 40% and 50% identity with the H2A, H2B and H3 somatic core histones of other plant species. Transcripts of these genes were first detected in bicellular pollen soon after microspore mitosis, and their mRNAs, as revealed by in situ hybridization, were observed only in the cytoplasm of the generative cells. As expression of these three genes was specific to generative cells within the bicellular pollen, we designated the clones gH2A, gH2B and gH3. Immunocytochemistry further revealed that the proteins encoded by these genes accumulated in the elongating and condensing generative nucleus during development of bicellular pollen, and were most abundant in the two sperm nuclei within an elongated pollen tube. We therefore propose that these male gamete-specific core histones contribute to chromatin condensation of male gametes or to chromatin remodeling, and result in the repression of gene expression in male gametes.

Characterization of bacterial-type phosphoenolpyruvate carboxylase expressed in male gametophyte of higher plants

“…Flower buds of 3-5 cm contain microspores, and PMI is completed by the 7 cm flower bud stage [24]. The GC morphology changes from round to spindle-like shape in the 12-14 cm stages [25], and the pollen reaches maturity at anthesis. Immunoblot analysis of LlBTPC during pollen development demonstrated that LlBTPC accumulation starts after PMI, and the amount increases to the 12 cm flower bud stage, and is sustained at this level until after anthesis (Figure 3B).…”

DNA damage response in male gametes of Cyrtanthus mackenii during pollen tube growth

“…This suggests the possibility that DSB recognition and/or DSB repair strategy are functioning in the generative cells but not in the vegetative cells. In the pollen of L. longiflorum , male-gamete-specific histone genes, including H2A , have been discovered, and the histone genes are expressed in the generative cell but not in the vegetative cell and the somatic cell (Xu et al 1999; Ueda et al 2000). It is inferred that one of the reasons for vegetative nuclei without the foci is the difference in histone usage between the generative nucleus and the vegetative nucleus, and ATM cannot phosphorylate the histone distributed in the vegetative nucleus.…”

The male gamete membrane protein DMP9/DAU2 is required for double fertilization in flowering plants

“…For lily, RNA extraction from pollen samples from each developmental stage and cDNA production were performed as previously described (Ueda et al, 2000). For Arabidopsis, total RNA was reverse transcribed with SuperScriptIII reverse transcriptase (ThermoFisher Scientific) and oligo(dT) primers to synthesize first-strand cDNA.…”