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Functional delineation of rice MADS29 reveals its role in embryo and endosperm development by affecting hormone homeostasis

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Title Functional delineation of rice MADS29 reveals its role in embryo and endosperm development by affecting hormone homeostasis
 
Creator Nayar, Saraswati
Sharma, Rita
Tyagi, Akhilesh K.
Kapoor, Sanjay
 
Subject Cytokinin
embryo
endosperm
MADS box
Oryza sativa
starch
seed development
 
Description Accepted date: 27 June 2013
Rice MADS29 has recently been reported to cause programmed cell death of maternal tissues, the nucellus, and the nucellar projection during early stages of seed development. However, analyses involving OsMADS29 protein expression domains and characterization of OsMADS29 gain-of-function and knockdown phenotypes revealed novel aspects of its function in maintaining hormone homeostasis, which may have a role in the development of embryo and plastid differentiation and starch filling in endosperm cells. The MADS29 transcripts accumulated to high levels soon after fertilization; however, protein accumulation was found to be delayed by at least 4 days. Immunolocalization studies revealed that the protein accumulated initially in the dorsal-vascular trace and the outer layers of endosperm, and subsequently in the embryo and aleurone and subaleurone layers of the endosperm. Ectopic expression of MADS29 resulted in a severely dwarfed phenotype, exhibiting elevated levels of cytokinin, thereby suggesting that cytokinin biosynthesis pathway could be one of the major targets of OsMADS29. Overexpression of OsMADS29 in heterologous BY2 cells was found to mimic the effects of exogenous application of cytokinins that causes differentiation of proplastids to starch-containing amyloplasts and activation of genes involved in the starch biosynthesis pathway. Suppression of MADS29 expression by RNAi severely affected seed set. The surviving seeds were smaller in size, with developmental abnormalities in the embryo and reduced size of endosperm cells, which also contained loosely packed starch granules. Microarray analysis of overexpression and knockdown lines exhibited altered expression of genes involved in plastid biogenesis, starch biosynthesis, cytokinin signalling and biosynthesis.
The authors gratefully acknowledge Department of
Biotechnology, Government of India for funding this project.
 
Date 2015-11-09T10:39:10Z
2015-11-09T10:39:10Z
2013
 
Type Article
 
Identifier J. Exp. Bot., 64(14): 4239-4253
0022-0957
http://172.16.0.77:8080/jspui/handle/123456789/350
http://jxb.oxfordjournals.org/content/64/14/4239
10.1093/jxb/ert231
 
Language en_US
 
Publisher Oxford University Press