During development, young fern leaves (= fronds) are coiled. It occurs during favourable growing season. As in other seed plants, the microgametophyte (male, or sperm-producing gametophyte) is highly simplified and called a pollen grain.The megagametophyte (female, or egg-producing, gametophyte) develops within the ovule (immature seed). It occurs during favourable growing season. Vegetative reproduction occurs only in the gametophytic stage. The gametophyte comprises the main plant (the green moss or liverwort), while the diploid sporophyte is much smaller and is attached to the gametophyte. The spores germinate and develop into a tiny, free-living gametophyte. Ans: Regular heteromorphic alternation of generation occurs in bryophytes. However, a spreading mass of pollen tubes on placental lobes was observed at 21 days after pollination (DAP) during meiosis on MMCs near completion, and the embryo sac entered two nuclear stages. Fertilization is porogamous: … The zygote produced after fertilization must undergo various cellular divisions and differentiations to become a mature embryo. The pollen grain must be released and transported to the ovule-bearing structure before fertilization can occur. In the sporophyte phase, haploid spores are formed and in the gametophyte phase, diploid male and female gametes are formed. Because the gametophytes themselves are haploid, however, they produce gametes by mitosis rather than meiosis. When a bryophyte spore settles somewhere, it grows into a gametophyte… the spores develop into a gametophyte stage plant which may be male or female 3. Plants have two distinct stages in their lifecycle: the gametophyte stage and the sporophyte stage. During the gametophyte stage, haploid (n) gametes or reproductive cells such as sperm and eggs are developed. Sporophyte production is also influenced by strong intra- and interspecific competition of microscopic stages (Reed, 1990; Reed et al., 1991). Fusion of the male and females gametes forms the diploid zygote, which develops into the sporophyte. Asexual reproduction occurs when a sporophyte releases spores, and sexual reproduction happens when gametes fuse and form a zygote. The diploid sporophyte stage is prominent against the haploid gametophyte in ferns. If the sperm do manage to get to an egg, fertilisation occurs, and that is where the two – the sperm and egg – come together. patterning the male gametophyte. Pollination is defined as the shed of pollen from the male anthers to the stigma or receptive surface of the gynoecium. It takes place by the parts of the vegetative plant or by the production of special vegetative propagules. gametophyte reproductive stage: A gametophyte development stage that occurs during the interval between the initiation of a gametangium and the onset of senescence. The male microspores travel to the embryonic sac to fuse with the ovum and the two polar nuclei to form the seed that matures for approximately 1 month. Fertilization occurs almost 7–8 weeks after pollination (WAP). ... although it may produce some of its own food by photosynthesis in the early stages of growth. Highly condensed chromatin is likely to improve the hydro-dynamic properties of the sperm nucleus and in animal systems this is essential for male fertility (Erenpreiss et al., (a) (b) (c) (d) (e) … The Haploid Stage. That doubles the number of chromosomes and that gives rise to a whole new typical fern plant again, and the cycle repeats. During fertilization male and female gametes fuse producing a diploid ie containing paired chromosomes zygote. The sporophyte stage of bryophytes is diploid, with two versions of each chromosome in its DNA, while the gametophyte is haploid with only one. Live-cell imaging and transcriptome analysis of single female gametophyte cell reveal novel insights into the dynamics and mechanisms of cell fate specifications in the model plant Arabidopsis.