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BMC Plant Biology 2013
Expression-based and co-localization detection of arabinogalactan protein 6 and arabinogalactan protein 11 interactors in Arabidopsis pollen and pollen tubesKeywords: Arabidopsis, Arabinogalactan proteins, Pollen tube, Microarray, Yeast two-hybrid Abstract: The lack of two specific AGPs induced a meaningful shift in the gene expression profile. In fact, a high number of genes showed altered expression levels, strengthening the case that AGP6 and AGP11 are involved in complex phenomena. The expression levels of calcium- and signaling-related genes were found to be altered, supporting the known roles of the respective proteins in pollen tube growth. Although the precise nature of the proposed interactions needs further investigation, the putative involvement of AGPs in signaling cascades through calmodulin and protein degradation via ubiquitin was indicated. The expression of stress-, as well as signaling- related, genes was also changed; a correlation that may result from the recognized similarities between signaling pathways in both defense and pollen tube growth.The results of yeast two-hybrid experiments lent further support to these signaling pathways and revealed putative AGP6 and AGP11 interactors implicated in recycling of cell membrane components via endocytosis, through clathrin-mediated endosomes and multivesicular bodies.The data presented suggest the involvement of AGP6 and AGP11 in multiple signaling pathways, in particular those involved in developmental processes such as endocytosis-mediated plasma membrane remodeling during Arabidopsis pollen development. This highlights the importance of endosomal trafficking pathways which are rapidly emerging as fundamental regulators of the wall physiology.Pollen-pistil interaction is initiated when the male gametophyte is transferred from the anther to the stigma. The pollen grain then starts to hydrate and germinate, forming a pollen tube that grows through the carpel’s internal tissues to deliver its two sperm cells into the embryo sac. Pollen tubes elongate through the extracellular matrix of the pistil tissues, extending by an actin-myosin-based tip-growth mechanism that transports vesicles loaded with new cell wall material to the extending apex and finally, wh
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