Arabidopsis AT-hook Protein TEK Positively Regulates the Expression of Arabinogalactan Proteins for Nexine Formation

Jia, Qi; Zhu, Jun; Xu, Xiao; Lou, Yue; Zhang, Zhan Lin; Zhang, Zhi Ping; Yang, Zhong‐Nan

doi:10.1016/j.molp.2014.10.001

Cited by 76 publications

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References 42 publications

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“…The exine is further divided into a species-specific sexine and a flat nexine [2]. The major composition of the sexine is sporopollenin [3], while the nexine is mainly composed of glycoproteins [4]. The biological function of the sexine layer is to provide an external barrier for adapting the terrestrial environment to ensure microgamete survival in land plants to resist various environmental stresses and microbial attacks [5, 6].…”

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confidence: 99%

OsACOS12, an orthologue of Arabidopsis acyl-CoA synthetase5, plays an important role in pollen exine formation and anther development in rice

Guo

et al. 2016

BMC Plant Biol

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BackgroundSporopollenin is a major component of the pollen exine pattern. In Arabidopsis, acyl-CoA synthetase5 (ACOS5) is involved in sporopollenin precursor biosynthesis. In this study, we identified its orthologue, OsACOS12, in rice (Oryza sativa) and compared the functional conservation of ACOS in rice to Arabidopsis.ResultsSequence analysis showed that OsACOS12 shares 63.9 % amino acid sequence identity with ACOS5. The osacos12 mutation caused by a pre-mature stop codon in LOC_Os04g24530 exhibits defective sexine resulting in a male sterile phenotype in rice. In situ hybridization shows that OsACOS12 is expressed in tapetal cells and microspores at the transcript level. The localization of OsACOS12-GFP demonstrated that OsACOS12 protein is accumulated in tapetal cells and anther locules. OsACOS12 driven by the ACOS5 promoter could partially restore the male fertility of the acos5 mutant in Arabidopsis.Conclusions OsACOS12 is an orthologue of ACOS5 that is essential for sporopollenin synthesis in rice. ACOS5 and OsACOS12 are conserved for pollen wall formation in monocot and dicot species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0943-9) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

OsACOS12, an orthologue of Arabidopsis acyl-CoA synthetase5, plays an important role in pollen exine formation and anther development in rice

Guo

et al. 2016

BMC Plant Biol

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“…The nexine is composed of outer nexine I (foot layer), which contains sporopollenin, and inner nexine II (endexine; Ariizumi and Toriyama, 2011;Jiang et al, 2013). A recent study suggests that arabinogalactan proteins (AGPs) are key constituents of nexine with expression of AtAGP6 in the nexinedeficient mutant transposable element silencing via athook (tek) partially restoring nexine formation (Jia et al, 2015). The materials comprising the exine are derived 1 This work was supported by KAKENHI grant no.…”

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KNS4/UPEX1: A Type II Arabinogalactan β-(1,3)-Galactosyltransferase Required for Pollen Exine Development

et al. 2016

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Pollen exine is essential for protection from the environment of the male gametes of seed-producing plants, but its assembly and composition remain poorly understood. We previously characterized Arabidopsis (Arabidopsis thaliana) mutants with abnormal pollen exine structure and morphology that we named kaonashi (kns). Here we describe the identification of the causal gene of kns4 that was found to be a member of the CAZy glycosyltransferase 31 gene family, identical to UNEVEN PATTERN OF EXINE1, and the biochemical characterization of the encoded protein. The characteristic exine phenotype in the kns4 mutant is related to an abnormality of the primexine matrix laid on the surface of developing microspores. Using light microscopy with a combination of type II arabinogalactan (AG) antibodies and staining with the arabinogalactan-protein (AGP)-specific b-Glc Yariv reagent, we show that the levels of AGPs in the kns4 microspore primexine are considerably diminished, and their location differs from that of wild type, as does the distribution of pectin labeling. Furthermore, kns4 mutants exhibit reduced fertility as indicated by shorter fruit lengths and lower seed set compared to the wild type, confirming that KNS4 is critical for pollen viability and development. KNS4 was heterologously expressed in Nicotiana benthamiana, and was shown to possess b-(1,3)-galactosyltransferase activity responsible for the synthesis of AG glycans that are present on both AGPs and/or the pectic polysaccharide rhamnogalacturonan I. These data demonstrate that defects in AGP/pectic glycans, caused by disruption of KNS4 function, impact pollen development and viability in Arabidopsis.Pollen, the male gametophyte of all seed plants, is crucial for reproductive success. Due to the harsh environmental conditions that pollen must survive in, it has developed an elaborate and specialized cell wall. However, despite its importance our knowledge of the fine structure and assembly of the pollen grain wall is poorly understood (Newbigin et al., 2009;Ariizumi and Toriyama, 2011;Quilichini et al., 2015;Shi et al., 2015). Arabidopsis (Arabidopsis thaliana) provides an ideal genetic and cell biological model to dissect the assembly of the components of the pollen grain wall. Arabidopsis pollen grains have a typical surface structure that consists of an inner intine layer, which is usually made up of cellulose and pectin, and the outer exine, which is largely composed of sporopollenin (Li et al., 1995). The exine is further subdivided into inner nexine and outer sexine. The sexine has a three-dimensional (3D) structure composed of many columns called baculae and a roof called tectum. These two structures give the Arabidopsis pollen surface a reticulate appearance with a uniform mesh size. The nexine is composed of outer nexine I (foot layer), which contains sporopollenin, and inner nexine II (endexine; Ariizumi and Toriyama, 2011;Jiang et al., 2013). A recent study suggests that arabinogalactan proteins (AGPs) are key constituents of nexine with express...

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“…Additional work on AHL16 has demonstrated that it can act not only as a repressor but also as an activator of transcription. AHL16 binds to AT-rich promoters of genes encoding arabinogalactan proteins, including AGP6, AGP11, AGP23, and AGP40, and activates their expression during the development of the pollen wall (Lou et al, 2014;Jia et al, 2015).…”

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SUPPRESSOR OF PHYTOCHROME B4-#3 Represses Genes Associated with Auxin Signaling to Modulate Hypocotyl Growth

et al. 2016

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Developing seedlings are well equipped to alter their growth in response to external factors in order to maximize their chances of survival. SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3) and other members of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family of transcription factors modulate the development of Arabidopsis (Arabidopsis thaliana) by repressing hypocotyl elongation in young seedlings growing in light. However, the molecular mechanism behind how AHLs influence seedling development is largely unknown. We have identified genes associated with auxin-mediated hypocotyl elongation as downstream targets of SOB3. We found that YUCCA8 (YUC8) as well as members of the SMALL AUXIN UP-REGULATED RNA19 (SAUR19) subfamily were down-regulated in the short-hypocotyl, gain-of-function SOB3-D mutant and up-regulated in the dominant-negative, tall-hypocotyl sob3-6 mutant. SOB3-D and sob3-6 hypocotyls also exhibited altered sensitivity to the polar auxin transport inhibitor N-1-napthylphthalamic acid, suggesting a critical connection between auxin and the modulation of seedling elongation by SOB3. Finally, we found that overexpression of GREEN FLUORESCENT PROTEIN-SAUR19 in the SOB3-D line partially rescued defects in hypocotyl elongation, and SOB3 bound directly to the promoters of YUC8 and SAUR19 subfamily members. Taken together, these data indicate that SOB3 modulates hypocotyl elongation in young seedlings by directly repressing the transcription of genes associated with auxin signaling.

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Arabidopsis AT-hook Protein TEK Positively Regulates the Expression of Arabinogalactan Proteins for Nexine Formation

Cited by 76 publications

References 42 publications

OsACOS12, an orthologue of Arabidopsis acyl-CoA synthetase5, plays an important role in pollen exine formation and anther development in rice

OsACOS12, an orthologue of Arabidopsis acyl-CoA synthetase5, plays an important role in pollen exine formation and anther development in rice

KNS4/UPEX1: A Type II Arabinogalactan β-(1,3)-Galactosyltransferase Required for Pollen Exine Development

SUPPRESSOR OF PHYTOCHROME B4-#3 Represses Genes Associated with Auxin Signaling to Modulate Hypocotyl Growth

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