Regulation of a Sub-sexual Life Cycle in a Moss: Evidence for the Occurrence of a Factor for Apogamy in Physcomitrium

• Published in: Annals of botany 1977-11, Vol.41 (6), p.1179-1189
• Main Authors: MENON, M. K. C., LAL, M.
• Format: Article
• Language: English
• ISSN: 0305-7364; 1095-8290
• DOI: 10.1093/oxfordjournals.aob.a085408

As demonstrated in our earlier studies, the differentiation of apogamous sporophytes on the secondary protonema of the moss Physcomitrium pyriforme Brid. requires an exogenous supply of sucrose in the medium. In the present work, similar differentiation was observed in the leaf cells of aged gametophytes. The experiments indicate an accumulation in the leaves of a sporophytic factor which initiates a de novo differentiation of sporophytes from leaf cells without the intervention of sexual reproduction. In the absence of sucrose, the factor for apogamy was not present. Highlight intensity (5000–6000 lx) also inhibited its production. There was no evidence that its presence interfered with or inhibited production of gameto-phores. Growth regulators such as IAA and kinetin altered only the effectiveness of this sporophytic factor, demonstrating that it was endogenous. Sporogenesis in the apogamous sporophytes took place without orthodox meiosis. Results obtained by using different exogenous environments for the in vitro differentiation of callus into gametophytes or sporophytes are also reported. These support our contention that there is an accumulation of a sporophytic factor in the gametophytic callus cells, which is diluted during the process of differentiation. The morpho-regulatory influence of light in the differentiation of apical cells with three cutting faces from unorganized callus is also considered.