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Impaired auxin biosynthesis in the defective endosperm18 mutant is due to mutational loss of expression in the ZmYuc1 gene encoding endosperm-specific YUCCA1 protein in maize

Citation

Bernardi, J and Lanubile, A and Li, QB and Kumar, D and Kladnik, A and Cook, SD and Ross, JJ and Marocco, A and Chourey, PS, Impaired auxin biosynthesis in the defective endosperm18 mutant is due to mutational loss of expression in the ZmYuc1 gene encoding endosperm-specific YUCCA1 protein in maize, Plant Physiology, 160, (3) pp. 1318-1328. ISSN 0032-0889 (2012) [Refereed Article]


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Copyright Statement

Copyright 2012 American Society of Plant Biologists.

DOI: doi:10.1104/pp.112.204743

Abstract

The phytohormone auxin (indole-3-acetic acid [IAA]) plays a fundamental role in vegetative and reproductive plant development. Here, we characterized a seed-specific viable maize (Zea mays) mutant, defective endosperm18 (de18) that is impaired in IAA biosynthesis. de18 endosperm showed large reductions of free IAA levels and is known to have approximately 40% less dry mass, compared with De18. Cellular analyses showed lower total cell number, smaller cell volume, and reduced level of endoreduplication in the mutant endosperm. Gene expression analyses of seed-specific tryptophan-dependent IAA pathway genes, maize Yucca1 (ZmYuc1), and two tryptophan-aminotransferase co-orthologs were performed to understand the molecular basis of the IAA deficiency in the mutant. Temporally, all three genes showed high expression coincident with high IAA levels; however, only ZmYuc1 correlated with the reduced IAA levels in the mutant throughout endosperm development. Furthermore, sequence analyses of ZmYuc1 complementary DNA and genomic clones revealed many changes specific to the mutant, including a 2-bp insertion that generated a premature stop codon and a truncated YUC1 protein of 212 amino acids, compared with the 400 amino acids in the De18. The putative, approximately 1.5-kb, Yuc1 promoter region also showed many rearrangements, including a 151-bp deletion in the mutant. Our concurrent high-density mapping and annotation studies of chromosome 10, contig 395, showed that the De18 locus was tightly linked to the gene ZmYuc1. Collectively, the data suggest that the molecular changes in the ZmYuc1 gene encoding the YUC1 protein are the causal basis of impairment in a critical step in IAA biosynthesis, essential for normal endosperm development in maize.

Item Details

Item Type:Refereed Article
Keywords:corn, IAA auxin, biosynthesis, tar, IPyA
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Environmental Sciences
Author:Cook, SD (Mr Sam Cook)
Author:Ross, JJ (Associate Professor John Ross)
ID Code:81400
Year Published:2012
Funding Support:Australian Research Council (DP110102085)
Web of Science® Times Cited:32
Deposited By:Plant Science
Deposited On:2012-12-04
Last Modified:2013-05-14
Downloads:0

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