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Effects of IAA, ZT, and GA3 on pollen tube growth in Torenia fournieri. Vertical bars represent standard errors in three independent experiments. Means denoted by the same upper-case letters and the same lower-case letters do not significantly differ at P
Source publication
The effects of several hormones on pollen tube growth were compared in Torenia fournieri and it was found that IAA was the most effective, stimulating pollen tube growth and causing the shank part of pollen tubes
to be slender and straighter. The role of IAA was investigated by studying the changes in ultrastructure and PM H+-ATPase distribution in...
Citations
... The functions of Parenchyma cells are given by Wist and Davis (2006). The role of Indole-3-acetic acid (IAA) in the pollen tube growth is presented by Wu et al. (2008). The role of microsporangia in pollen development called microsporogenesis is described by Rudall (2020). ...
... It further promotes the maturation of egg cells along with the polar development of the embryo (Aloni et al. 2006;Mol et al. 2004;Nemhauser et al. 2000). IAA functional activities were also found to influence pollen tube growth in Torenia fournieri (Wu et al. 2008). In addition, it can initiate anther dehiscence (Cecchetti et al. 2008), affect stamen development, and its flow can improve the elongation of stamen filament (Hirano et al. 2008). ...
Key message
Dose effects of Rf1 gene regulated retrieval mechanism of pollen fertility for CMS-D2 cotton.
Abstract
Cytoplasmic male sterility conditioned by Gossypium harknessii cytoplasm (CMS-D2) is an economical pollination control system for producing hybrid cotton seeds compared to artificial and chemical emasculation methods. However, the unstable restoring ability of restorer lines is a main barrier in the large-scale application of “three-line” hybrid cotton in China. Our phenotypic investigation determined that the homozygous Rf1Rf1 allelic genotype had a stronger ability to generate fertile pollen than the heterozygous Rf1rf1 allelic genotype. To decipher the genetic mechanisms that control the differential levels of pollen fertility, an integrated metabolomic and transcriptomic analysis was performed at two environments using pollen grains of four cotton genotypes differing in Rf1 alleles or cytoplasm. Totally 5,391 differential metabolite features were detected, and 369 specific differential metabolites (DMs) were identified between homozygous and heterozygous Rf1 allelic genotypes with CMS-D2 cytoplasm. In addition, transcriptome analysis identified 2,490 differentially expressed genes (DEGs) and 96 unique hub DEGs with dynamic regulation in this comparative combination. Further integrated analyses revealed that several key DEGs and DMs involved in indole biosynthesis, flavonoid biosynthesis, and sugar metabolism had strong network linkage with fertility restoration. In vitro application of auxin analogue NAA and inhibitor Auxinole confirmed that over-activated auxin signaling might inhibit pollen development, whereas suppressing auxin signaling partially promoted pollen development in CMS-D2 cotton. Our results provide new insight into how the dosage effects of the Rf1 gene regulate pollen fertility of CMS-D2 cotton.
... Auxin (IAA) is the most important hormone that stimulates pollen tube growth by modifying the tube wall composition and structure (Wu, Lin, et al., 2008;Zhang et al., 2018). However, pollen tube growth is inhibited by high concentration of IAA (Zhang et al., 2018). ...
Heat stress has a negative impact on pollen development in maize (Zea mays L.) but the postpollination events that determine kernel sterility are less well characterised. The impact of short-term (hours) heat exposure during postpollination was therefore assessed in silks and ovaries. The temperatures inside the kernels housed within the husks was significantly lower than the imposed heat stress. This protected the ovaries and possibly the later phase of pollen tube growth from the adverse effects of heat stress. Failure of maize kernel fertilization was observed within 6 h of heat stress exposure postpollination. This was accompanied by a significant restriction of early pollen tube growth rather than pollen germination. Limitations on early pollen tube growth were therefore a major factor contributing to heat stress-induced kernel sterility. Exposure to heat stress altered the sugar composition of silks, suggesting that hexose supply contributed to the limitations on pollen tube growth. Moreover, the activities of sucrose metabolising enzymes, the expression of sucrose degradation and trehalose biosynthesis genes were decreased following heat stress. Significant increases in reactive oxygen species, abscisic acid and auxin levels accompanied by altered expression of phytohormone-related genes may also be important in the heat-induced suppression of pollen tube growth.
... It further promotes the maturation of egg cells along with the polar development of the embryo (Aloni, et al. 2006;Mol, et al. 2004;Nemhauser, et al. 2000). IAA functional activities were also found to in uence pollen tube growth in Torenia fournieri (Wu, et al. 2008). Also, it can initiate anther dehiscence (Cecchetti, et al. 2008), affect stamen development, and its ow can improve the elongation of stamen lament (Hirano, et al. 2008). ...
CMS-D2 is an economical and effective system for producing hybrid cotton seeds than artificial and chemical emasculation methods. However, the unstable restoring ability of restorer lines is a main barrier in the large-scale application of "three-line" hybrid cotton. Our phenotypic investigation determined that the homozygous Rf 1 Rf 1 allelic genotype had a stronger ability to generate fertile pollen than the heterozygous Rf 1 rf 1 allelic genotype. To decipher the genetic mechanisms that control the differential levels of pollen fertility, an integrated metabolomic and transcriptomic analysis was performed on pollen grains at two environments using four cotton genotypes differing in Rf 1 alleles or cytoplasm. Totally 5,391 differential metabolite features were detected, and 369 specific differential metabolites (DMs) were identified between homozygous and heterozygous Rf 1 allelic genotypes with CMS-D2 cytoplasm. Additionally, transcriptome analysis identified 2,490 differentially expressed genes (DEGs) and 96 unique hub DEGs with dynamic regulation in this comparative combination. Further integrated analyses revealed that several key DEGs and DMs involved in indole biosynthesis, flavonoid biosynthesis, and sugar metabolism had strong network linkage with fertility restoration. In vitro application of auxin analogue NAA and inhibitor Auxinole confirmed that over-activated auxin signaling might inhibit pollen development whereas suppressing auxin signaling partially promoted pollen development in CMS-D2 cotton. Our results provide new insight into how the dosage effects of the Rf 1 gene regulate pollen fertility of CMS-D2 cotton.
... This leads to reducing the competition of fruits for nutrients at this stage. Also, the balanced nutritional status in the plant may increase the production of auxin in the flowering stage, which plays a major role in increasing the percentage of nodes [Banker and Prased phenomenon of self-incompatibility and even crossincompatibility sometimes, and that the cause of selfincompatibility is due to the fact that Sidr flowers are protandrous and hetrodichogamous [Wu et al. (2008)]. The results in Table 1 indicated the effect of soil conditioners and irrigation water quality on the percentage of fruit set, as the salt fighter treatment significantly excelled the organic fertilizer treatment and the control treatment, and recorded the highest average of 13.42%. ...
This study was conducted in one of the orchards of Basra province, where 27 jujube trees were selected. The study included two factors: the first factor (the factor of soil conditioners), as it uses decomposed sheep's residues by adding it to the soil at an amount of 25 kg/tree. The industrial enhancer used a salinity processor (salt-fighter-700) at a concentration of 1 L per 100 L of irrigation water. The second factor (irrigation water quality factor) included river water as a control (3 ds.m-1) and (8 ds.m-1) and (12 dm.m-1). The results of the study showed that the use of soil conditioners, especially the salt fighter, improved the growth traits of jujube trees, which was positively reflected in the physiological and anatomical traits of jujube fruits. The salt fighter treatment significantly excelled on the organic fertilizer treatment and the control treatment, and the highest average was recorded for most of the studied traits (the percentage of fruit set 13.42%, the thickness of the epidermal layer was 27.96 m, the thickness of the sub-epidermal layer was 120.10 m, the diameter of stone cells was 19.36 m, and the thickness of the mesocarp layer was 523.95 m. The interaction between the treatment of salt fighter and irrigation with river water gave the highest rates for the same traits above, and gave the lowest average of fruit drop 84%, the thickness of the cuticle layer 3.44 µm and the diameter of the tannin cells 21.22 µm.
... Our finding is consistent with the expression data from the published synergid database (Okuda et al. 2009) and, in addition, demonstrates that the expression of TfPMEI1 is synergid-specific (Fig. 5). Previous studies suggested that IAA stimulates pollen tube growth and direction through the modification of pectin and cellulose in the tube wall, favoring PME's role in pollen tube growth (Wu et al. 2008). A more recent study showed that levels of methylesterified and de-esterified pectin in the filiform apparatus regulated by PME-PMEI are associated with prevention of polyspermy (Duan et al. 2020); we infer that TfPMEI1 may play a role ...
The expression pattern of an interested gene at a cellular level provides strong evidence for its functions. RNA in situ hybridization has been proved to be a powerful tool in detecting the spatial–temporal expression pattern of a gene in various organisms. However, classical RNA in situ hybridization (ISH) technique is time-consuming and requires sophisticated sectioning skills. Therefore, we developed a method for whole-mount in situ hybridization (WISH) on ovules of Torenia fournieri, which is a model species in the study of plant reproduction. T. fournieri possesses ovules with protruding embryo sacs, making it easy to be observed and imaged through simple manipulation. To determine the effect of classical ISH and our newly established WISH, we detected the expression of a D-class gene, TfSTK3, using both methods. The expression patterns of TfSTK3 are similar in classical ISH and WISH, confirming reliability of the WISH method. Compared with WISH, classical ISH always leads to distorted embryo sacs, hence difficult to distinguish signals within the female gametophyte. To understand whether our WISH protocol also works well in detecting genes expressed within embryo sacs, we further examined the expression of a synergid-enriched candidate, TfPMEI1, and clearly observed specific signals within two synergid cells. To summarize, our WISH technique allows to visualize gene expression patterns in ovules of T. fournieri within one week and will benefit the field of plant reproduction in the future.
... Since the exogenous application of auxin has positive effects on tip growth in terrestrial plants [28][29][30], we first examined whether tip growth from a single-celled conchocelis could be stimulated by the exogenous application of indole-3-acetic acid ...
... Since the exogenous application of auxin has positive effects on tip growth in terrestrial plants [28][29][30], we first examined whether tip growth from a single-celled conchocelis could be stimulated by the exogenous application of indole-3-acetic acid (IAA). However, no effect was observed (data not shown), suggesting that if auxin is required for tip growth, an adequate amount was already present in the isolated cells. ...
The red alga Neopyropia yezoensis undergoes polarized elongation and asymmetrical cell
division of the apical stem cell during tip growth in filamentous generations of its life cycle: the conchocelis and conchosporangium. Side branches are also produced via tip growth, a process involving the regeneration and asymmetrical division of the apical stem cell. Here, we demonstrate that auxin plays a crucial role in these processes by using the auxin antagonist 2-(1H-Indol-3-yl)-4- oxo-4-phenyl-butyric acid (PEO-IAA), which specifically blocks the activity of the auxin receptor TRANSPORT INHIBITOR RESPONSE1 (TIR1) in land plants. PEO-IAA repressed both the regeneration and polarized tip growth of the apical stem cell in single-celled conchocelis; this phenomenon was reversed by treatment with the auxin indole-3-acetic acid (IAA). In addition, tip growth of the conchosporangium was accelerated by IAA treatment but repressed by PEO-IAA treatment. These findings indicate that auxin regulates polarized tip cell growth and that an auxin receptor-like protein is present in N. yezoensis. The sensitivity to different 5-alkoxy-IAA analogs differs considerably between N. yezoensis and Arabidopsis thaliana. N. yezoensis lacks a gene encoding TIR1, indicating that its auxin receptor-like protein differs from the auxin receptor of terrestrial plants. These findings shed light on auxin-induced mechanisms and the regulation of tip growth in plants.
... In our study, DEGs related to auxin and ethylene signalling were identified, and were downregulated. Auxin has been shown to influence pollen tube germination and growth (Wu et al. 2008;Gao et al. 2019), and impairment of auxin signalling affects pollen tube germination (see Fig. 1h). In Arabidopsis, ARF17 has been implicated in pollen wall patterning ). ...
Drought stress is detrimental to male reproduction in maize (Zea mays L.), largely through reducing the quantity and quality of pollen grains. However, transcriptional response of maize pollen grains to drought stress has not been well documented. We compared pollen gene expression for a maize hybrid (ZhongDan909) under well-watered and drought-stress conditions, based on RNA-Seq validated by quantitative real-time PCR analysis. Expression of 6424 genes and 1302 transcripts was altered in pollen grains of maize subjected to 7 days of drought during flowering. Gene Ontology annotations showed 308 differentially expressed genes, annotated and classified into 50 primary functional categories. Kyoto Encyclopedia of Genes and Genomes analyses revealed 44 differentially expressed genes in nine metabolic pathways. In relation to carbohydrate metabolism pathways, there was downregulation of a polygalacturonase gene, which could reduce cell wall lysis in early pollen germination, and an increase in callose synthase transcripts along with reduced cellulase transcripts. These altered gene expressions responsible for cell wall integrity may inhibit the initiation of pollen tube growth. The onset of tube growth could be further impeded by observed changes in gene expression that potentially influence hormone metabolism (including downregulation of AUXIN RESPONSE FACTOR 18 and EIN3-BINDING F-BOX), reduce mitochondrial function, and alter protein translation. Genes with potential roles in adaptation were also altered in their transcript levels. These included genes encoding the upregulated transcription factor ZmNF-YC2, and the downregulated ZmbHLH13, a negative regulator of jasmonic acid responses. The upregulated flavin enzyme gene DIHYDROLIPOYL DEHYDROGENASE 1, associated with increased levels of reactive oxygen species, is of interest in relating redox homeostasis to stress adaptation. Overall, the analyses identified a suite of genes involved in the development of pollen grains and tubes and responsive to drought stress. The findings enhance understanding of the gene networks underlying compromised pollen viability under drought stress.
... Auxin is an important endogenous hormone that promotes plant growth and development. Not only does it regulate the formation and differentiation of ovary and ovule before pollination, but also directly or indirectly regulates the interaction among pollen, pistil and the polar growth of pollen tube (Wu et al., 2008a). In the present study, the content of IAA increased in the pistil after pollination, suggesting that IAA probably participate in pollen tube growth in the pistil (Aloni et al., 2006), which consistent with the report that IAA decreased in the parts where pollen tubes penetrated the style of Nicotiana tabacum (Chen and Zhao, 2008). ...
Tea plant is confronted with several limitations, such as self-incompatibility, which poses a great challenge to tea breeding. In this study, this physiological response and molecular insights of incompatibility reaction in self-pollinated and cross-pollinated pistils of tea plant were analyzed to explore the factors involved in incompatible reaction. Aniline blue staining analysis revealed no significant difference in pollen germination, and pollen tubes reached the base of the style at 48 h after self- and cross-pollination, thus, ovary is a critical location involving incompatible reaction. Transcribe data of self- and reciprocal cross-pollinated pistils showed that CsMCU2 (mitochondrial calcium uniporter protein 2 in C. sinensis) may be a gene related to incompatible process of tea plants. Gene expression profiles showed that the expression levels of CsMCU2 were tissue-specific, and may be related to incompatible reaction in tea plants. The patterns of variability of endogenous hormones contents in styles and ovaries varied with type of pollination and tea plant, indicating that incompatible reactions may have different regulatory mechanism in tea plants. This study provides reference for further study on incompatible response in tea plants.
... Auxin has been shown to be critical for pollen development. External applications of auxin can stimulate in vitro pollen tube growth of Nicotiana tabacum and Torenia fournieri 38,39 . Studies on the pollen-specific auxin efflux carrier PIN8 also support a role for auxin in pollen tube 40,41 . ...
Flavonoids play important roles in regulating plant growth and development. In this study, three kaempferol 3-O-glycosides were identified and mainly accumulated in flowers but not in leaves or fruits of Malus. In Malus, flower petal color is normally white, but some genotypes have red flowers containing anthocyanin. Anthocyanin biosynthesis appears to be in competition with kaempferol 3-O-glycosides production and controlled by the biosynthetic genes. The white flower Malus genotypes had better-developed seeds than the red flower genotypes. In flowers, the overexpression of MYB10 in Malus domestica enhanced the accumulation of anthocyanin, but decreased that of kaempferol 3-O-glycosides. After pollination the transgenic plants showed slower pollen tube growth and fewer developed seeds. Exogenous application of different flavonoid compounds suggested that kaempferol 3-O-glycosides, especially kaempferol 3-O-rhamnoside, regulated pollen tube growth and seed set rather than cyanidin or quercetin 3-O-glycosides. It was found that kaempferol 3-O-rhamnoside might regulate pollen tube growth through effects on auxin, the Rho of plants (ROP) GTPases, calcium and the phosphoinositides signaling pathway. With the inhibition of auxin transport, the transcription levels of Heat Shock Proteins (HSPs) and ROP GTPases were downregulated while the levels were not changed or even enhanced when blocking calcium signaling, suggesting that HSPs and ROP GTPases were downstream of auxin signaling, but upstream of calcium signaling. In summary, kaempferol glycoside concentrations in pistils correlated with auxin transport, the transcription of HSPs and ROP GTPases, and calcium signaling in pollen tubes, culminating in changes to pollen tube growth and seed set.
