FRAGMENT FROM NATURE continues from last weekend and concludes this weekend on the theme of the female carpel of flowering plants, a structure that significantly advanced this group of plants in their evolution. View in LinkedIn
THE GATE AGAINST INBREEDING. “In addition, the carpel provides a location for selective mechanisms that operate on pollen, such as self-incompatibility, which promotes out-breeding.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
TOWARDS THE FUSION EVENTS. “Following pollination, compatible pollen tubes are guided with meticulous accuracy through the tissues of the carpel, specifically toward unfertilized ovules.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
CARPELS MAKE THE FRUIT. “After fertilization, the carpel tissues undergo further developmental changes to become the fruit, which protects the developing seeds and later contributes to the dissemination of these by a wide variety of mechanisms in different species.” https://lnkd.in/dbZEjuz View in LinkedIn
GIANT LEAP FORWARD. “For all of these reasons, the carpel was undoubtedly a major factor in the evolutionary success of the angiosperms, which diversified from a common ancestor that is estimated to have lived in the Late Jurassic period, around 160 million years ago (MYA), to form approximately 300 000 species alive today.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
FROM LEAF TO CARPEL. “Carpels, along with the other principal floral organs, have for long been postulated to be modified from a leaf ground plan. Relatively recent experimental evidence supports this view: floral organs are converted to leaves in plants in which all of the A, B and C function genes, or the redundant E-function genes, are inactivated.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
NUANCED ORIGINS. “Although the carpel appears to be a modified leaf, it may be more directly related to sporophylls, or leaves that carry spore-producing organs. As the carpel is female, it has traditionally been regarded as derived from megasporophylls that would have subtended ovules in the pre-angiosperm lineage. Accordingly, the carpel would be directly homologous to such gymnosperm organs as the female cone scales of conifers.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
FEMALE ORIGIN THEORY. “A recent molecular explanation for the origin of the bisexual axis in the flowering plants, termed the Out-of-Male/Out-of-Female Theory, is broadly consistent with this view of a female origin for the carpel.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
BISEXUAL THEORY. “This theory proposes a pair of alternative mechanisms, based on the movement of a frontier of B-function gene expression in either a basipetal or acropetal direction along male or female reproductive axes, respectively, in the pre-angiosperm lineage. As a result, the axis affected is proposed to have become bisexual, with female organs at its tip and male organs at its base. Carpels would then have evolved by the closure of megasporophylls in the apical region of the bisexual axis.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
MALE THEORY. “Conversely, the ‘Mostly Male Theory’ proposes the carpel to have been derived by the closure of (male) microsporophylls, around ovules that had developed ectopically on these. According to this view, all or most of the female-specific developmental pathways in the pre-angiosperm lineage, other than those required for ovule development, were lost during the evolution of the first angiosperms.” https://academic.oup.com/jxb/article/57/10/2143/471376/An-evolutionary-perspective-on-the-regulation-of View in LinkedIn
