Development of sporophyte from the gametophytic tissue without involving fusion of gametes is known as:

Question

Accepted Answer

The correct option is 2: Apogamy

Apogamy is a crucial concept in the study of the alternation of generations in plants, particularly observed in ferns and some bryophytes, but the principle also applies to the development within angiosperms. It is fundamentally defined as the development of the diploid sporophyte generation directly from a haploid gametophytic cell or tissue without the prior formation or fusion of gametes. In a typical plant life cycle, the haploid gametophyte produces gametes, which must fuse (syngamy) to form a diploid zygote, and this zygote then develops into the sporophyte. Apogamy, however, completely bypasses the sexual act of fertilization. The initial cell of the sporophyte is a vegetative cell of the gametophyte (n) that develops directly into a sporophyte (2n), often after its chromosome number doubles spontaneously through a process like endoreduplication. This non-sexual development of the sporophyte from the gametophyte is a powerful demonstration of the plasticity in plant reproductive strategies.

The incorrect option is 1: Apospory

Apospory describes the development of a gametophyte directly from sporophytic tissue, a process which is the exact reverse of what the question describes. Normally, the diploid sporophyte produces haploid spores through meiosis, which germinate to form the haploid gametophyte. In apospory, a diploid gametophyte arises from any vegetative cell of the sporophyte (e.g., nucellus, integuments, or fern sporangium stalk) without the intervention of meiosis or spores. The resulting gametophyte is diploid, but since it develops *from* the sporophyte *to* the gametophyte, it is incorrect for the question.

The incorrect option is 3: Parthenocarpy

Parthenocarpy is a term used exclusively in angiosperms (flowering plants) and refers to the development of fruit without the act of fertilization. This phenomenon results in seedless fruits, such as bananas, pineapples, and seedless grapes. Parthenocarpy involves the maturation of the ovary into a fruit independent of ovule fertilization. While it is an asexual reproductive strategy, it relates specifically to the fruit and seed formation within the sporophyte generation and has no connection with the initiation of a sporophyte from gametophytic tissue.

The incorrect option is 4: Metaxenia

Metaxenia is a highly specific phenomenon that describes the immediate effect of foreign pollen on the tissues *surrounding* the embryo and endosperm, meaning the maternal tissue of the fruit. This effect is often visible on the fruit or seed coat in the year of pollination. For example, the presence of specific pollen can immediately influence the size, color, or ripening time of the surrounding fruit tissue. Metaxenia is therefore an influence on the maternal sporophytic structure (fruit/pericarp) rather than an alternative pathway for the formation of the sporophyte generation itself, making it an irrelevant answer for this biological context.