Maternal control of seed size by EOD3/CYP78A6 in Arabidopsis thaliana

State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
The Plant Journal (Impact Factor: 5.97). 01/2012; 70(6):929-39. DOI: 10.1111/j.1365-313X.2012.04907.x
Source: PubMed


Seed size in higher plants is coordinately determined by the growth of the embryo, endosperm and maternal tissue, but relatively little is known about the genetic and molecular mechanisms that set final seed size. We have previously demonstrated that Arabidopsis DA1 acts maternally to control seed size, with the da1-1 mutant producing larger seeds than the wild type. Through an activation tagging screen for modifiers of da1-1, we have identified an enhancer of da1-1 (eod3-1D) in seed size. EOD3 encodes the Arabidopsis cytochrome P450/CYP78A6 and is expressed in most plant organs. Overexpression of EOD3 dramatically increases the seed size of wild-type plants, whereas eod3-ko loss-of-function mutants form small seeds. The disruption of CYP78A9, the most closely related family member, synergistically enhances the seed size phenotype of eod3-ko mutants, indicating that EOD3 functions redundantly with CYP78A9 to affect seed growth. Reciprocal cross experiments show that EOD3 acts maternally to promote seed growth. eod3-ko cyp78a9-ko double mutants have smaller cells in the maternal integuments of developing seeds, whereas eod3-1D forms more and larger cells in the integuments. Genetic analyses suggest that EOD3 functions independently of maternal factors DA1 and TTG2 to influence seed growth. Collectively, our findings identify EOD3 as a factor of seed size control, and give insight into how plants control their seed size.

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Available from: Wenjuan Fang, Mar 23, 2015
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    • "It has been shown that CYP78A family members are involved in reduced fertility; functional deletion or overexpression of CYP78A members led to a reduced seed set (Ito and Meyerowitz, 2000; Adamski et al., 2009; Fang et al., 2012; Sotelo-Silveira et al., 2013). All these reductions in fertility involved the female reproductive organ. "
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    ABSTRACT: There are several studies describing quantitative trait loci (QTL) for seed size in wheat, but the relevant genes and molecular mechanisms remain largely unknown. Here, we report the functional characterization of the wheat TaCYP78A3 gene and its effect on seed size. TaCYP78A3 encoded wheat cytochrome P450 CYP78A3 and was specifically expressed in wheat reproductive organs. TaCYP78A3 activity was positively correlated with the final seed size. Its silencing caused cell number reduction in the seed coat, resulting in a 11% decrease in wheat seed size, whereas TaCYP78A3 overexpression induced more cells in the seed coat, leading to a 11%~48% increase in Arabidopsis seed size. In addition, the cell number of the final seed coat was determined by the TaCYP78A3 expression level, which affected the extent of integument cell proliferation in the developing ovule and seed. Unfortunately, TaCYP78A3 overexpression caused a reduced seed set due to an ovule developmental defect in Arabidopsis. Moreover, TaCYP78A3 overexpression affected embryo development by promoting embryo integument cell proliferation during seed development, which also ultimately affected the final seed size in Arabidopsis. In summary, our results indicated that TaCYP78A3 plays critical roles in influencing seed size by affecting the extent of integument cell proliferation. The present study provides direct evidence that TaCYP78A3 functions in affecting seed size in wheat and contributes to an understanding of the cellular basis of the gene influencing seed development. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    The Plant Journal 06/2015; DOI:10.1111/tpj.12896 · 5.97 Impact Factor
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    • "In situ hybridization was performed as described ( Li et al . , 2003 ; Fang et al . , 2012 ) . DIG - labeled RNA transcripts were generated by transcription of KLU in antisense orientation using T7 RNA polymerase ( Roche ) . After hybridization , washing , and blocking , DIG - labeled RNA transcripts re - acting with alkaline phosphatase - conjugated anti - DIG Fab fragment ( 1 : 3000 [ v / v ] ; Roche ) were detected using 5"
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    ABSTRACT: Although seed size is one of the most important agronomic traits in plants, the genetic and molecular mechanisms that set the final size of seeds are largely unknown. We previously identified the ubiquitin receptor DA1 as a negative regulator of seed size, and the Arabidopsis thaliana da1-1 mutant produces larger seeds than the wild type. Here, we describe a B3 domain transcriptional repressor NGATHA-like protein (NGAL2), encoded by the suppressor of da1-1 (SOD7), which acts maternally to regulate seed size by restricting cell proliferation in the integuments of ovules and developing seeds. Overexpression of SOD7 significantly decreases seed size of wild-type plants, while the simultaneous disruption of SOD7 and its closest homolog DEVELOPMENT-RELATED PcG TARGET IN THE APEX4 (DPA4/NGAL3) increases seed size. Genetic analyses indicate that SOD7 and DPA4 act in a common pathway with the seed size regulator KLU to regulate seed growth, but do so independently of DA1. Further results show that SOD7 directly binds to the promoter of KLUH (KLU) in vitro and in vivo and represses the expression of KLU. Therefore, our findings reveal the genetic and molecular mechanisms of SOD7, DPA4, and KLU in seed size regulation and suggest that they are promising targets for seed size improvement in crops. © 2015 American Society of Plant Biologists. All rights reserved.
    The Plant Cell 03/2015; 27(3). DOI:10.1105/tpc.114.135368 · 9.34 Impact Factor
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    • "expansion in the integuments of developing seeds (Ito & Meyerowitz 2000; Fang et al. 2012). However, the expression of CYP78A is inconsistent with proliferating regions where mutant phenotypes are observed, and the mutants are not rescued by classic phytohormones, indicating that CYP78A might involve in a novel mobile factor controlling organ growth (Adamski et al. 2009). "
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    ABSTRACT: Grain size is one of the most important determinants of crop yield in cereals. Here, we identified a dominant mutant, big grain2 (bg2-D) from our enhancer-trapping population. Genetic analysis and SiteFinding PCR revealed that BG2 encodes a cytochrome P450, OsCYP78A13. Squence search revealed that CYP78A13 has a paralogue Grain Length 3.2 (GL3.2, LOC_Os03g30420) in rice with distinct expression patterns, analysis of transgenic plants harboring either CYP78A13 or GL3.2 showed that both can promote grain growth. Sequence polymorphism analysis with 1,529 rice varieties showed that the nucleotide diversity at CYP78A13 gene body and the 20-kb flanking region in the indica varieties were markedly higher than those in japonica varieties. Further, comparison of the genomic sequence of CYP78A13 in the japonica cultivar Nipponbare and the indica cultivar 9311 showed that there were 3 InDels in the promoter region and 8 SNPs in its coding sequence. Detailed examination of the transgenic plants with chimaeric constructs suggested that variation in CYP78A13 coding region is responsible for the variation of grain yield. Taken together, our results suggest that the variations in CYP78A13 in the indica varieties hold potential in rice breeding for application of grain yield improvement.
    Plant Cell and Environment 09/2014; 38(4). DOI:10.1111/pce.12452 · 6.96 Impact Factor
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