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Publications - Cell and Metabolic Biology

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Weier, D., Thiel, J., Kohl, S., Tarkowská, D., Strnad, M., Schaarschmidt, S., Weschke, W., Weber, H. & Hause, B. Gibberellin-to-abscisic acid balances govern development and differentiation of the nucellar projection of barley grains. J Exp Bot 65, 5291-5304, (2014) DOI: 10.1093/jxb/eru289

In cereal grains, the maternal nucellar projection (NP) constitutes the link to the filial organs, forming a transfer path for assimilates and signals towards the endosperm. At transition to the storage phase, the NP of barley (Hordeum vulgare) undergoes dynamic and regulated differentiation forming a characteristic pattern of proliferating, elongating, and disintegrating cells. Immunolocalization revealed that abscisic acid (ABA) is abundant in early non-elongated

but not in differentiated NP cells. In the maternally affected shrunken-endosperm mutant seg8, NP cells did not elongate and ABA remained abundant. The amounts of the bioactive forms of gibberellins (GAs) as well as their biosynthetic precursors were strongly and transiently increased in wild-type caryopses during the transition and early storage phases. In seg8, this increase was delayed and less pronounced together with deregulated gene expression

of specific ABA and GA biosynthetic genes. We concluded that differentiation of the barley NP is driven by a distinct and specific shift from lower to higher GA:ABA ratios and that the spatial–temporal change of GA:ABA balances is required to form the differentiation gradient, which is a prerequisite for ordered transfer processes through the NP. Deregulated ABA:GA balances inseg8 impair the differentiation of the NP and potentially compromise transfer of signals and assimilates, resulting in aberrant endosperm growth. These results highlight the impact of hormonal balances on the proper release of assimilates from maternal to filial organs and provide new insights into maternal effects on endosperm differentiation and growth of barley grains.


Wasternack, C. & Hause, B. Emerging complexity: jasmonate-induced volatiles affect parasitoid choice J Exp Bot 60, 2451-2453, (2009) DOI: 10.1093/jxb/erp197

Plant responses to specific environmental stimuli at the molecular and genetic levels have been widely reported in recent decades, mainly as a consequence of the availability of new laboratory techniques. However, understanding the complex implications of these observations at the ecosystem level remains one of the greatest challenges facing plant science today. Recently, new experimental strategies have been designed to address complex interactions. For example, combinations of different insects have been used to study insect–plant interactions (Dicke et al., 2009) as well as parallel analysis of the responses to different types of pathogen which reflect more closely the conditions encountered in natural ecosystems (Pieterse et al., 2009).

In this issue, the two papers by Bruinsma and colleagues also address such complex issues; the detailed analysis of plant responses to different herbivores and JA application are documented, and the responses of parasitic wasps that attack the herbivores are recorded. The authors’ experimental design and interpretation of the results highlight the importance of understanding the complexity of plant responses in the context of a whole ecosystem.

In the last two decades, interest in plant–insect interactions using ecological, chemical, and molecular approaches has increased dramatically. Direct defence reactions of plants, such as the production of toxins or deterrent proteins like proteinase inhibitors, as well as indirect defence reactions, have been identified showing that the effectiveness of the natural enemies of attackers can be altered. In the latter case, the induced release of volatiles is a common phenomenon leading to the attraction of carnivores. Plants attacked by herbivores respond with the establishment of a chemical phenotype, releasing volatiles into the atmosphere that include terpenoids, phenylpropanoids or fatty acid-derived green leaf volatiles. The detailed composition of the volatile blend is insect-specific and depends on the type of attacker (e.g. chewing or sucking … 

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