| The large endosperm of maize is a nutritive tissue for embryo development, but also important for the primary food products and industrial applications, which make maize the central crop of agriculture. It is clear that maize endosperm develops from the fertilized central cell, originates with repeated free-nuclear divisions followed by cellularization and intensive mitosis, and subsequently forms four differential cell types. Yet the regulation of maize endosperm development remains poorly understood.1. Here, we report the molecular characterization of a Wrinkled kernell (Wrkl) mutant in maize. The endosperm of the Wrkl mutant is deeply furrowed and impacted by gene dosage, whereas the seedling is small but vigorous.2. The section of kernel at10,12and16DAP (day after pollination) showed that the effects of Wrk1mutation are manifest in formation of starch endosperm cells and transfer layer cells. Size of endosperm at5DAP is much smaller than wild type, and the situation is aggravated at7DAP, showing that the endosperm gets defective in morphology and cell growth. The results indicated that Wrk1may be involved in mitosis of endosperm cell.3. Immunostaining of spindle by β-tubulin antibody at anaphase of mitosis in endosperm cells revealed that Wrkl mutant is defective in sister chromatid segregation resulting in chromosome bridge and chromosome lagging.4. Utilized the positional cloning strategy, we mapped the causative mutation to a350-kb region, which contains three predicted gene models. A gene model encoding β-tubulin5protein shows a C to T transition leading to a premature stop codon at the3’end. The truncated ZmTUBB5completely lacks C-terminal tail of isotype-defining region.5. Transformed kernels with exceeded mutation allele of ZmTubb5versus normal allele showed wrinkled crow.These results demonstrate that Wrkl encodes the ZmTUBB5which is critical for endosperm development and mitosis in maize. |
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