Genome-wide analysis reveals divergent patterns of gene expression during zygotic and somatic embryo maturation of Theobroma cacaoL., the chocolate tree

BMC Plant Biology

Research Article

Wayne Curtis¹  Sergio Florez¹  Yufan Zhang²  Siela N Maximova²  Xiangling Shen²  Mark J Guiltinan²  Nicolas Niemenak³ 

[1] Department of Chemical Engineering, The Pennsylvania State University, 16802, University Park, Pennsylvania, USA;Department of Plant Science and Huck Institute of Life Sciences, The Pennsylvania State University, 16802, University Park, PA, USA;Laboratory of Plant Physiology, Department of Biological Science, Higher Teachers’ Training College, University of Yaounde, Yaounde, Cameroon;

关键词: Theobroma cacao;    Somatic embryogenesis;    Zygotic embryogenesis;    Embryogenesis;    Microarray;    Gene expression;   

DOI  :  10.1186/1471-2229-14-185

 received in 2014-02-28, accepted in 2014-07-03,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundTheobroma cacao L. is a tropical fruit tree, the seeds of which are used to create chocolate. In vitro somatic embryogenesis (SE) of cacao is a propagation system useful for rapid mass-multiplication to accelerate breeding programs and to provide plants directly to farmers. Two major limitations of cacao SE remain: the efficiency of embryo production is highly genotype dependent and the lack of full cotyledon development results in low embryo to plant conversion rates. With the goal to better understand SE development and to improve the efficiency of SE conversion we examined gene expression differences between zygotic and somatic embryos using a whole genome microarray.ResultsThe expression of 28,752 genes was determined at 4 developmental time points during zygotic embryogenesis (ZE) and 2 time points during cacao somatic embryogenesis (SE). Within the ZE time course, 10,288 differentially expressed genes were enriched for functions related to responses to abiotic and biotic stimulus, metabolic and cellular processes. A comparison ZE and SE expression profiles identified 10,175 differentially expressed genes. Many TF genes, putatively involved in ethylene metabolism and response, were more strongly expressed in SEs as compared to ZEs. Expression levels of genes involved in fatty acid metabolism, flavonoid biosynthesis and seed storage protein genes were also differentially expressed in the two types of embryos.ConclusionsLarge numbers of genes were differentially regulated during various stages of both ZE and SE development in cacao. The relatively higher expression of ethylene and flavonoid related genes during SE suggests that the developing tissues may be experiencing high levels of stress during SE maturation caused by the in vitro environment. The expression of genes involved in the synthesis of auxin, polyunsaturated fatty acids and secondary metabolites was higher in SEs relative to ZEs despite lack of lipid and metabolite accumulation. These differences in gene transcript levels associated with critical processes during seed development are consistent with the fact that somatic embryos do not fully develop the large storage cotyledons found in zygotic embryos. These results provide insight towards design of improved protocols for cacao somatic embryogenesis.

【 授权许可】

Unknown   
© Maximova et al.; licensee BioMed Central Ltd. 2014. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.