Archives

  • 2018-07
  • 2018-10
  • 2018-11
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • Although no data exist on Ptc gene

    2022-01-21

    Although no data exist on Ptc52 gene acetylcholine receptors in other plant species, the expression pattern presented in this study shows perceptibly low levels of transcript accumulation in tomato seeds and roots, low levels in the stem, flower and green fruit, and high levels in the leaves. This coincides with the expression pattern of other genes from the Lls1-PaO family which display low expression levels in non-photosynthetic tissues, in which the wound-inducible Lls1 gene from maize is present (Yang et al., 2004). In our study we have not separated the different parts of the flower, and therefore it cannot rule out that the relative high SlPtc52 expression levels detected in flowers might be due to the presence of the sepals, the outer parts of the flower, often green and leaf-like. Similarly, there are no previous reports about the response of Ptc52 genes to plant hormone treatment. Our results indicate a complex response to the application of exogenous hormones highlighting that MeJA could enhance the expression levels of SlPtc52. These results suggest that the expression of SlPtc52 may be regulated by MeJA-dependent defence signalling pathways as has been shown for wheat Pheophorbide a Oxygenase gene TaPao (MA et al., 2012). Furthermore, PAO-like Rieske oxygenase transcripts were induced in leaves infected by fungal pathogens upon physical wounding (Tang et al., 2013), indicating that PAO-like protein function may be regulated by phytohormones in response to stress. It is also important to note that the response to hormonal treatment in roots (this study) can differ from that observed in leaves (previous study). The Ptc52 gene was previously identified as specifically up-regulated in the roots of mycorrhizal tomato plants (GarcĂ­a-Garrido et al., 2010), while, in this study, its temporal and spatial expression pattern associated with AM symbiosis is characterized. Our results suggest that SlPtc52 gene expression increases concomitantly with the colonization of the root, in which its spatial expression pattern shows that SlPtc52 expression in mycorrhizal roots is mainly confined to arbusculated cells, suggesting that PTC52 plays a role in those cells. Changes in the pattern of mycorrhization were analysed in SlPtc52 RNAi mycorrhizal hairy roots, whose percentage of root length colonized decreased after 50 days of colonization. Although the intensity of mycorrhizal colonization (m%) in the colonized root fragments was similar in both control and SlPtc52 RNAi plants, arbuscule abundance (%a) was lower in the latter. This could indicate that the delay observed in colonization has a selective, adverse arbuscular effect, which then affects the frequency and intensity of colonization. This is in line with our findings on the localization of SlPtc52 promoter activity in the cells with arbuscules. Although TIC55 and PTC52 are considered to be components of distinct TIC and PTC protein import complexes, respectively, in the chloroplast, the role of the latter complex in protein import into leaves has been the subject of some debate (Kim and Apel, 2004). Four of the five Rieske-type oxygenases in Arabidopsis are associated with chlorophyll metabolism, and it has been proposed that PTC52 oxidates protochlorophyllide a to protochlorophyllide b (Gray et al., 2002). Furthermore, these proteins have been predicted to encode an oxygenase related to the Lethal leaf spot 1 (Lls1) lesion mimic gene in plants (Gray et al., 2004) which is sometimes associated with enhanced disease resistance (Wolter et al., 1993; Dietrich et al., 1994). In this respect, silencing of TaLls1 in wheat does not change the disease symptoms but rather enhances tolerance to Puccinia striiformis through a significant increase in H2O2 generation, elevated cell death and pathogenesis-related gene upregulation (Tang et al., 2013). It is therefore tempting to hypothesize that something similar happens in SlPtc52-silenced RNAi tomato plants which would prevent normal arbuscular development.