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Kenji Omasa - One of the best experts on this subject based on the ideXlab platform.

  • rice oryza sativa l cultivars tolerant to high temperature at flowering anther characteristics
    Annals of Botany, 2002
    Co-Authors: Tsutomu Matsui, Kenji Omasa
    Abstract:

    We examined the relationship between morphological characteristics of anthers and fertility in japonica rice cultivars subjected to high temperature (37·5/26 ∞C day/night) at flowering. Percentage fertility was negatively correlated with the number of cell layers that separated the anther Locule from the lacuna that formed between the septum and the stomium. The cell layers consisted of the remaining septum and degraded tapetum, and serve to keep the adjacent two Locules closed. Anther dehiscence therefore requires the rupture of the cell layers. We conclude that the tight closure of the Locules by the cell layers delayed Locule opening, and decreased fertility at high temperatures. a 2002 Annals of Botany Company

  • comparison between anthers of two rice oryza sativa l cultivars with tolerance to high temperatures at flowering or susceptibility
    Plant Production Science, 2001
    Co-Authors: Tsutomu Matsui, Kenji Omasa, Takeshi Horie
    Abstract:

    Anthers of rice cultivar, cv. Nipponbare, which showed floret fertility even when the temperature at flowering was high (tolerant) and cv. Hinohikari, which showed floret sterility at high temperatures (susceptible) were compared. The anther of Nipponbare had better developed cavities for dehiscence and thicker Locule walls than Hinohikari. The well-developed cavities enable easy rupture of the septa in response to swelling of the pollen grains. The thick Locule walls promote the swelling of pollen grains by retaining water in the Locules. Since the swelling of pollen grains is the driving force to open the theca and the septum rupture is an indispensable process for the theca dehiscence, the well-developed cavities and the thick Locule walls may be responsible for the tolerance to high temperatures in Nipponbare.

  • mechanism of anther dehiscence in rice oryza sativa l
    Annals of Botany, 1999
    Co-Authors: Tsutomu Matsui, Kenji Omasa, Takeshi Horie
    Abstract:

    Abstract This paper presents a new explanation of the mechanism of anther dehiscence in rice during the period from floret opening to pollen dispersal. The theca dehisced on the stomium in the apical part and the anther wall in the basal part of the large Locule. Comparison of the anther dehiscence process under various air humidity conditions showed that the process, until the splitting at the apical and basal parts, was a moisture-requiring process whereas the widening of the splits in both parts was a desiccatory process. Observation of the anther transverse section, revealed the marked development of the U-shaped thick cell wall in the endothecium adjacent to these two splits. From these observations, the anther dehiscence mechanism may be explained as follows. At the time of anthesis, pollen grains swell rapidly in response to the floret opening and cause the theca to bulge, rupturing the septum. The pollen pressure combined with the inward bending of the Locule walls adjacent to the stomium causes splitting of the stomium in the apical part of the theca. At the same time, the septum rupture extends to the bottom of the large Locule supported by the pollen pressure. After these processes, the Locule walls adjacent to both splits straighten probably due to their water loss. This straightening widens the splits and the swollen pollen grains overflow from the widened splits.

Tsutomu Matsui - One of the best experts on this subject based on the ideXlab platform.

  • rice oryza sativa l cultivars tolerant to high temperature at flowering anther characteristics
    Annals of Botany, 2002
    Co-Authors: Tsutomu Matsui, Kenji Omasa
    Abstract:

    We examined the relationship between morphological characteristics of anthers and fertility in japonica rice cultivars subjected to high temperature (37·5/26 ∞C day/night) at flowering. Percentage fertility was negatively correlated with the number of cell layers that separated the anther Locule from the lacuna that formed between the septum and the stomium. The cell layers consisted of the remaining septum and degraded tapetum, and serve to keep the adjacent two Locules closed. Anther dehiscence therefore requires the rupture of the cell layers. We conclude that the tight closure of the Locules by the cell layers delayed Locule opening, and decreased fertility at high temperatures. a 2002 Annals of Botany Company

  • comparison between anthers of two rice oryza sativa l cultivars with tolerance to high temperatures at flowering or susceptibility
    Plant Production Science, 2001
    Co-Authors: Tsutomu Matsui, Kenji Omasa, Takeshi Horie
    Abstract:

    Anthers of rice cultivar, cv. Nipponbare, which showed floret fertility even when the temperature at flowering was high (tolerant) and cv. Hinohikari, which showed floret sterility at high temperatures (susceptible) were compared. The anther of Nipponbare had better developed cavities for dehiscence and thicker Locule walls than Hinohikari. The well-developed cavities enable easy rupture of the septa in response to swelling of the pollen grains. The thick Locule walls promote the swelling of pollen grains by retaining water in the Locules. Since the swelling of pollen grains is the driving force to open the theca and the septum rupture is an indispensable process for the theca dehiscence, the well-developed cavities and the thick Locule walls may be responsible for the tolerance to high temperatures in Nipponbare.

  • mechanism of anther dehiscence in rice oryza sativa l
    Annals of Botany, 1999
    Co-Authors: Tsutomu Matsui, Kenji Omasa, Takeshi Horie
    Abstract:

    Abstract This paper presents a new explanation of the mechanism of anther dehiscence in rice during the period from floret opening to pollen dispersal. The theca dehisced on the stomium in the apical part and the anther wall in the basal part of the large Locule. Comparison of the anther dehiscence process under various air humidity conditions showed that the process, until the splitting at the apical and basal parts, was a moisture-requiring process whereas the widening of the splits in both parts was a desiccatory process. Observation of the anther transverse section, revealed the marked development of the U-shaped thick cell wall in the endothecium adjacent to these two splits. From these observations, the anther dehiscence mechanism may be explained as follows. At the time of anthesis, pollen grains swell rapidly in response to the floret opening and cause the theca to bulge, rupturing the septum. The pollen pressure combined with the inward bending of the Locule walls adjacent to the stomium causes splitting of the stomium in the apical part of the theca. At the same time, the septum rupture extends to the bottom of the large Locule supported by the pollen pressure. After these processes, the Locule walls adjacent to both splits straighten probably due to their water loss. This straightening widens the splits and the swollen pollen grains overflow from the widened splits.

Meihua Sun - One of the best experts on this subject based on the ideXlab platform.

  • transcriptome analysis reveals regulatory effects of exogenous gibberellin on Locule number in tomato
    Plant Growth Regulation, 2020
    Co-Authors: Meihua Sun, Hengzuo Xiang, Sida Meng, Bo Wang
    Abstract:

    The size and shape of tomato (Solanum lycopersicum L.) fruit are determined by Locule number. Gibberellin (GA) can increase Locule number in tomato, but the underlying molecular mechanism is unclear. Therefore, in this study, multi-Locule ‘MLK1’ tomato seedlings with two to three true leaves (pre-flower bud differentiation) were sprayed with GA1, GA3, GA4, GA7, PAC (paclobutrazol; an inhibitor of GA biosynthesis) and H2O, as a control. We found that GA4 resulted in was the most significant increase in tomato Locule number among all bioactive GAs, while PAC decreased the Locule number. We analyzed the change in Locule number by RNA-seq, quantitative real-time PCR and ultra-performance liquid chromatography–tandem mass spectrometry. The categories ‘Phenylpropanoid biosynthesis’, ‘Plant hormone signal transduction’, and ‘Diterpenoid biosynthesis’ were considerably activated after spraying with GA4. Additionally, indole-3-acetic acid (IAA) content significantly increased and trans-Zeatin-riboside (tZ) content significantly reduced after exogenous GA4 application. We conclude that exogenous GA4 application changed the dynamic balance of hormones in the tomato shoot apex. Furthermore, 53 differentially expressed transcription factors were identified in tomato upon exogenous GA4 treatment during floral bud differentiation, including, YABBYs, TCP, NAC, and ARR (some directly regulate lateral organ development). Our results provide novel insights into how exogenous GA4 affects plant hormone homeostasis in the tomato shoot apex and the underlying mechanism of Locule number regulation by GA4 in tomato.

  • low overnight temperature induced gibberellin accumulation increases Locule number in tomato
    International Journal of Molecular Sciences, 2019
    Co-Authors: Meihua Sun, Hengzuo Xiang, Yudong Liu
    Abstract:

    The number of Locules in tomato affects fruit size, shape, and the incidence of malformation. Low temperature increases Locule number and the incidences of malformation in tomato plants. In this study, three flower bud developmental stages (pre-flower bud differentiation, sepal and petal primordium formation, and carpel primordium formation) under different night temperatures (10, 15, and 20 °C) were used to analyze the reason behind Locule number change using an RNA sequencing (RNA-seq) approach, Quantitative real-time PCR (qRT-PCR), and ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS). The results showed that the “plant hormone signal transduction”, “starch and sucrose metabolism”, and “diterpenoid biosynthesis” categories were remarkably activated during flower bud differentiation. Transcripts of gibberellin (GA)-related genes and endogenous levels of GAs were analyzed, and it was discovered that SlGA2ox genes were significantly downregulated and bioactive GA1 and GA4 accumulated at lower overnight temperature. Exogenous application of bioactive GA1, GA4, and PAC (paclobutrazol) showed that GA1 and GA4 increased the Locule number, while PAC decreased the Locule number. Taken together, our results suggest that lower overnight temperature reduced the expression of SlGA2ox genes, leading to GA1 and GA4 accumulation, thereby increasing Locule number in tomato.

  • alteration of slyabby2b gene expression impairs tomato ovary Locule number and endogenous gibberellin content
    Journal of Zhejiang University-science B, 2018
    Co-Authors: Meihua Sun, Jiao Xing, Hanting Liu
    Abstract:

    Tomato is an ideal model species for fleshy fruit development research. SlYABBY2b regulates the ovary Locule number, which is increased by gibberellins, in tomato. However, the relationship between SlYABBY2b and endogenous gibberellin is poorly understood. In this study, SlYABBY2b-overexpressing and RNA interference (RNAi) transgenic tomato plants were used to elucidate the mechanism by which SlYABBY2b regulates the ovary Locule number and endogenous gibberellin content in tomato. SlYABBY2b-overexpressing plants showed fewer Locules and lower gibberellin content than the control plants. Contrasting results were found in the RNAi lines. Therefore, the SlYABBY2b gene negatively regulates tomato ovary Locule number and endogenous gibberellin content. Furthermore, the expression of SlYABBY2b gene was remarkably higher than that of the wild type in the apical shoots of gibberellindeficient mutants. This showed that the gibberellins can inhibit the expression of SlYABBY2b gene negative regulation. Further study revealed that SlYABBY2b suppressed the expression of SlGA20ox1 and SlGA3ox2, but increased that of SlGA2ox1 and SlGA2ox5 in the apical shoots of SlYABBY2b-overexpressing plants, thereby reducing gibberellin content. Contrasting results were found in the RNAi lines. Our results showed that the SlYABBY2b gene was located on gibberellin signal transduction pathways, fed back regulation of the synthesis of gibberellin, and felt exogenous gibberellin signal to further regulate the formation of tomato Locule.

  • tomato transcription factor slwus plays an important role in tomato flower and Locule development
    Frontiers in Plant Science, 2017
    Co-Authors: Meihua Sun, Ying Liu, Yudong Liu
    Abstract:

    Tomato is a model species for fleshy fruit development. The shapes and sizes of tomato (Solanum lycopersicum L.) are mainly controlled by several loci, including Locule number (lc). Two single nucleotide polymorphisms were found downstream of WUSCHEL (SlWUS) in a putative tomato CArG cis-regulatory element. The lc mutation may affect the binding of AGAMOUS(AG), cause the up-regulation of SlWUS and result in increased Locule numbers. In this study, tissue expression levels showed that SlWUS is expressed in young floral buds and shoot apexes. Silencing SlWUS on an lc mutant genetic background with an RNA interference (RNAi) strategy resulted in smaller flowers and fruit than those of the wild-type plants, with decreased Locule number. Further study revealed that the SlWUS RNAi lines exhibited altered expression levels of the TAG1 and SlCLV3 genes that participate in the regulation of tomato flower and fruit Locule development. In conclusion, this study provides the first genetic evidence that SlWUS may be the candidate gene of the lc locus and reveals the function of SlWUS in flower development.

Donald J Huber - One of the best experts on this subject based on the ideXlab platform.

  • ripening of tomato fruit Locule gel tissue in response to ethylene
    Postharvest Biology and Technology, 2000
    Co-Authors: Mordy A Attaaly, Jeffrey K Brecht, Donald J Huber
    Abstract:

    Ethylene production by Locule gel tissue excised from immature tomato fruit was inhibited by exposure to 4.5 mmol l 1 C2H4, and 1-aminocyclopropane-1-carboxylic acid (ACC) content was reduced. In contrast, CO2 production, ethylene forming capacity (EFC), red colour development, tissue liquefaction and seed maturation as measured by subsequent germination rate were stimulated by C2H4, and, in immature gel, the onset of autocatalytic C2H4 production was hastened. The autoinhibition of C2H4 production in immature Locule gel tissue required continuous exposure to C2H4, as transfer to air and then back to C2H4 resulted in C2H4 production first increasing to control levels, then decreasing again. Locule gel tissue from pink fruit however, responded to C2H4 treatment with increased C2H4 and CO2 production, but ACC levels were unchanged. Inhibition of C2H4 action by pretreatment with STS inhibited both autoinhibition and autostimulation of C2H4 production in immature and mature gel tissues, respectively. These results indicate that there is a transition from a negative to a positive feedback mechanism of C2H4 on C2H4 biosynthesis in Locule gel during ripening. Control of this feedback mechanism, which involves ACC synthesis, may be separate from that of other manifestations of C2H4 action. © 2000 Elsevier Science B.V. All rights reserved.

  • carbohydrate solutilization of tomato Locule tissue cell walls parallels with Locule tissue liquefaction during ripening
    Physiologia Plantarum, 1997
    Co-Authors: Guiwen W Cheng, Donald J Huber
    Abstract:

    Carbohydrate solubilization and glycosidase activities were investigated in tomato (Lycopersicon esculentum Mill. cv. Solar Set) Locule cell walls to identity processes involved in the liquefaction of this tissue. Cell walls were prepared from the Locule tissue of fruit at the immature green, mature green, and breaker stages of development. Enzymically active walls incubated in dilute buffer released high molecular mass pectins, oligomeric carbohydrate, and the neutral sugars rhamnose, glucose, galactose, arabinose, xylose, and mannose. The release was sustained for at least 50 h at 34°C and was inhibited more than 50% by 1 mM Hg 2+ . Pectins released from the cell walls of Locule tissue at progressive stages of liquefaction were similar in molecular mass and showed no evidence of downshifts on a Sepharose CL-2B-300 column during prolonged incubation. A cell-free protein extract prepared from the Locule tissue of mature-green fruit promoted a net release of polymeric and monomeric carbohydrates from high-temperature inactivated cell walls. Polygalacturonase activity was not detected in Locule protein although glycosidases including β-mannosidase (EC 3.2.1.25), α- and β-galactosidases (EC 3.2.1.22-23), β-arabinosidase (EC 3.2.1.56) and #-glucosidase (EC 3.2.1.21) were present. Pectinmethylesterase (EC 3.1.1.11) activity was detected at the immature-green stage but declined to negligible levels in mature-green and breaker Locule tissue. Parallels between the in vitro solubilization of carbohydrate from Locule tissue cell walls and the changes occurring during Locule liquefaction are discussed.

  • alterations in structural polysaccharides during liquefaction of tomato Locule tissue
    Plant Physiology, 1996
    Co-Authors: G W Cheng, Donald J Huber
    Abstract:

    The Locule tissue of tomato (Lycopersicon esculentum, Mill.) undergoes extensive liquefaction during ripening. In this study, the solubility, molecular mass, and glycosyl composition of Locule pectic and alkali-soluble polysaccharides were examined with the aim of identifying features contributing to the unique properties of this tissue. Ethanol-insoluble solids were prepared from de-seeded Locule tissue from tomato fruit at the immature green (IMG), mature green, and breaker stages of development. Ethanol-insoluble pectins were extracted sequentially in H2O, 50 mM trans-1,2-diaminocyclohexane-N,N,N[prime],N[prime]-tetraacetic acid, 50 mM Na2CO3, and 4 M KOH. At the IMG stage, nearly 85% of the Locule pectins were solubilized by water, trans-1,2-diaminocyclohexane-N,N,N[prime],N[prime]-tetraacetic acid, and Na2CO3 solutions. Solubility increased only slightly with further Locule development. The noncovalently associated polymers were of high molecular mass throughout liquefaction. Polymers extracted in mild alkali were of considerably lower molecular mass. Locule pectins in IMG fruit were heavily glycosylated with galactose, arabinose, and xylose. All pectin classes exhibited similar deglycosylation trends during liquefaction. Locule hemicelluloses were rich in glucose, xylose, and arabinose. These polymers collectively showed molecular mass downshifts with minimal compositional changes during liquefaction. The KOH-soluble material also included xylose-rich acidic polymers not matching the neutral sugar profile of the noncovalently associated pectic polymers.

Unruh, Corinne M. - One of the best experts on this subject based on the ideXlab platform.

Related terms

  • tomato lycopersicon esculentum mill
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