The Arabidopsis HOBBIT gene encodes a CDC27 homolog that links the plant cell cycle to progression of cell differentiation

Abstract

In plant meristems, dividing cells interpret positional information and translate it into patterned cell differentiation. Here we report the molecular identification of the Arabidopsis HOBBIT gene that is required for cell division and cell differentiation in meristems. We show that it encodes a homolog of the CDC27 subunit of the anaphase-promoting complex (APC). HOBBIT partially complements a yeast nuc2/cdc27 mutant. Unlike other CDC27 homologs in Arabidopsis, its transcription is cell cycle regulated. Furthermore, hobbit mutants show a reduction in DR5 :: GUS auxin reporter gene expression and accumulate the AXR3/IAA17 repressor of auxin responses. HOBBIT activity may thus couple cell division to cell differentiation by regulating cell cycle progression in the meristem or by restricting the response to differentiation cues, such as auxin, to dividing cells.

Non-cell-autonomous rescue of anaphase-promoting complex function revealed by mosaic analysis of HOBBIT , an Arabidopsis CDC27 homolog

“…Epidermal cells in the tip region are much shorter and more swollen (Fig. 2B) than the WT cells, similar to the cells of strong hbt mutants (17). Before these visible shape changes, from 1 DAHS onward, cortical microtubules orient randomly ( Fig.…”

“…Most APC͞C components are expressed ubiquitously, and their mutation arrests the cell cycle early in plant development (13,14). In contrast, the CDC27 homolog HOBBIT (HBT) is present in cycling cells and their expanding daughters only and is predominantly required after embryogenesis (17). Here, we describe the effects of postembryonic removal of a single complementing HBT gene copy in a strong hbt mutant background.…”

Growth coordination and the shoot epidermis

“…HBT is a CDC27 homolog, which encodes a subunit of the Anaphase Promoting Complex or Cyclosome (APC/ C) [27]. Analysis of hbt plants suggests that HBT functions primarily post-embryonically to maintain normal cell division and expansion Figure 1d) [26*].…”

Functional Analysis of the Tandem-Duplicated P450 Genes SPS/BUS/CYP79F1 and CYP79F2 in Glucosinolate Biosynthesis and Plant Development by Ds Transposition-Generated Double Mutants

“…These reporters are useful to investigate changes in hormone levels within defined regions of wild-type and mutant plants (e.g. Casson et al, 2002;Harrar et al, 2003;Werner et al, 2003 for the cytokinin reporter ARR5; and Blilou et al, 2002;Long et al, 2002;Willemsen et al, 2003 for the auxin reporter DR5), because the hormone measurements on entire aerial parts of the plants may not reflect hormone levels at specific developmental sites, which may be masked by the changes elsewhere in the plant. We selected the sps1-1 allele for the investigation, as this allele does not exhibit b-glucuronidase (GUS) expression derived from the Ds gene trap insertion.…”