Functional Analysis of Arabidopsis TETRASPANIN Gene Family in Plant Growth and Development

Abstract

TETRASPANIN (TET) genes encode conserved integral membrane proteins that are known in animals to function in cellular communication during gamete fusion, immunity reaction, and pathogen recognition. In plants, functional information is limited to one of the 17 members of the Arabidopsis (Arabidopsis thaliana) TET gene family and to expression data in reproductive stages. Here, the promoter activity of all 17 Arabidopsis TET genes was investigated by pAtTET::NUCLEAR LOCALIZATION SIGNAL-GREEN FLUORESCENT PROTEIN/b-GLUCURONIDASE reporter lines throughout the life cycle, which predicted functional divergence in the paralogous genes per clade. However, partial overlap was observed for many TET genes across the clades, correlating with few phenotypes in single mutants and, therefore, requiring double mutant combinations for functional investigation. Mutational analysis showed a role for TET13 in primary root growth and lateral root development and redundant roles for TET5 and TET6 in leaf and root growth through negative regulation of cell proliferation. Strikingly, a number of TET genes were expressed in embryonic and seedling progenitor cells and remained expressed until the differentiation state in the mature plant, suggesting a dynamic function over developmental stages. The cis-regulatory elements together with transcription factor-binding data provided molecular insight into the sites, conditions, and perturbations that affect TET gene expression and positioned the TET genes in different molecular pathways; the data represent a hypothesis-generating resource for further functional analyses.

Fertilization Mechanisms in Flowering Plants

“…Tetraspanins are conserved in multicellular organisms including flowering plants [74] and they may also be involved in plant reproduction as some tetraspanins accumulate in male and female reproductive tissues and gametes. So far, however, gene knock out studies in Arabidopsis did not reveal reproduction-related phenotypes [75, 76] suggesting functional redundancies.…”

A tetraspanin gene regulating auxin response and affecting orchid perianth size and various plant developmental processes

“…The answer is largely revealed by the analysis of Arabidopsis AAF ortholog AtAAF . It is interestingly to note that AtAAF has been reported to be possibly regulated by MADS box gene AGL15 in Arabidopsis (Wang et al, ). Two putative MADS protein binding site of CArG boxes consensus sequence (CC(A/T) 6 GG) were identified in the promoter region of AtAAF (Figure ).…”

Emerging roles of tetraspanins in plant inter-cellular and inter-kingdom communication

“…12 In animals and plants, some tetraspanins have a broad tissue distribution, while others show a restricted expression; for instance, in plant cells, different tetraspanins are expressed in specialized tissues such as the reproductive tissue and meristems, during embryo development, and in specific cell niches, such as the quiescent center or the early initial cells that give rise to lateral roots. [13][14][15] Tetraspanins appear to act as molecular organizers by forming homo-or heterodimers that localize to microdomains known as tetraspanin-enriched microdomains (TEMs). As components of TEMs, both animal and plant tetraspanins maintain a network of interactions with other membrane proteins, such as integrins, and signaling molecules, such as receptors, allowing the assembly of multi-molecular signaling platforms.…”