Activation of E2F transcription factors at the G1-to-S phase boundary, with the resultant expression of genes needed for DNA synthesis and S-phase, is due to phosphorylation of the retinoblastoma-related (RBR) protein by cyclin D-dependent kinase (CYCD-CDK), particularly CYCD3-CDKA. Arabidopsis has three canonical E2F genes, of which E2Fa and E2Fb are proposed to encode transcriptional activators and E2Fc a repressor. Previous studies have identified genes regulated in response to high-level constitutive expression of E2Fa and of CYCD3;1, but such plants display significant phenotypic abnormalities. We have sought to identify targets that show responses to lower level induced changes in abundance of these cell cycle regulators. Expression of E2Fa, E2Fc or CYCD3;1 was induced using dexamethasone and the effects analysed using microarrays in a time course allowing short and longer term effects to be observed. Overlap between CYCD3;1 and E2Fa modulated genes substantiates their action in a common pathway with a key role in controlling the G1/S transition, with additional targets for CYCD3;1 in chromatin modification and for E2Fa in cell wall biogenesis and development. E2Fc induction led primarily to gene downregulation, but did not antagonise E2Fa action and hence E2Fc appears to function outside the CYCD3-RBR pathway, does not have a direct effect on cell cycle genes, and promoter analysis suggests a distinct binding site preference.

Nepenthes is a genus of 130-160 species, almost half of which were described after 2001. The recent, rapid increase in species descriptions has been driven by application of a less rigorous species concept by botanists, taxonomic inflation, and discoveries of new taxa during explorations of remote parts of Southeast Asia. Many recently published species descriptions of Nepenthes are based entirely upon qualitative morphological information and are not supported by adequate research. Accordingly, the status of many Nepenthes taxa is contested. Evolution within the genus is not well understood, because nuclear and maternally inherited plastid genomes cannot resolve relationships between many species, particularly those that evolved recently through introgression or reticulate evolution. Improvement in our understanding of the systematics and evolution of Nepenthes requires the adoption of ‘best practice’ collection and preservation methods, and the application of quantitative analytical methods for morphological, genetic, and ecological information.

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A new species of Nepenthes L., N. attenboroughii (Nepenthaceae), from Palawan Island in the Philippines, is described and illustrated. It is restricted to rocky, ultramafic soils that comprise the summit region of Mount Victoria, Municipality of Narra, where it occurs in isolation from other members of the genus. On the basis of the morphological features, this new taxon appears to be related to both N. mira Jebb & Cheek of Palawan and N. rajah Hook.f. of Borneo. Its substantial size places it among the largest of known pitcher plants. The diagnostic morphological characters are discussed and an updated key is provided for a revised complex of Nepenthes species from the Palawan and North Borneo phytogeographical region. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159, 195–202.

An expedition to the highest peak of the Kemul Massif located a number of different Nepenthes taxa, including the type populations of N. fusca Danser and N. mollis Danser (Nepenthaceae), neither of which have been observed in situ since they were first collected from Kemul in 1925. Studies of the type form of N. fusca show that N. fusca s.lat. includes two other species, one largely restricted to Sabah’s Crocker range, here reinstated as N. zakriana (J.H.Adam & Wilcock) J.H.Adam & Hafiza, and a more southerly distributed species from Brunei, Sarawak and Kalimantan, named here as N. dactylifera A.S.Rob, Golos & Barer. Analysis of the type population of N. mollis indicates that N. hurrelliana Cheek & A.L.Lamb is a heterotypic synonym of N. mollis, and reveals an additional undescribed Nepenthes species from Sarawak and Kalimantan with a widespread but highly localised range.