Symplastic Solute Transport and Avocado Fruit Development: A Decline in Cytokinin/ABA Ratio is Related to Appearance of the Hass Small Fruit Variant

Moore-Gordon, C. S.; Cowan, A. Keith; Bertling, I.; Botha, C. E. J.; Cross, R. H. M.

doi:10.1093/oxfordjournals.pcp.a029299

Cited by 36 publications

(31 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, considering previous studies arguing that the occurrence of small phenotypically 'Hass' fruits might be linked to changes in sink strength and sugar content and knowing that SF are characterized by decreased IAA content, yet by elevated ABA levels (Cowan et al 1997(Cowan et al , 2005Moore-Gordon et al 1998;Richings et al 2000), it is tempting to speculate that limiting sucrose supply and/or changes in fruit hormone homeostasis might control the accelerated repression of transcription of the two mitotic cyclins and PCNA in SF tissues.…”

Section: Discussionmentioning

confidence: 99%

“…For example, it was shown that SF are characterized by decreased sucrose content and increased glucose levels, as a proportion of total soluble sugars, as well as by a reduced capacity for cytosolic isoprenoid biosynthesis (Richings et al 2000). In addition, it was also reported that at early stages of fruit development, small-sized 'Hass' fruits are characterized by decreased auxin [indole-3-acetic acid (IAA)] content, yet present elevated levels of abscisic acid (ABA), a plant hormone implicated in stress-induced cell cycle arrest (Cowan et al 1997(Cowan et al , 2005Moore-Gordon et al 1998). Taken together, it was further suggested that changes in sugar content in sink fruit cells (speciWcally in sucrose/hexose ratio) might modulate hormone metabolism, aVecting fruit cell division activity ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A proposed conserved role for an avocado fw2.2-like gene as a negative regulator of fruit cell division

Dahan

Rosenfeld

Zadiranov

et al. 2010

Planta

View full text Add to dashboard Cite

Previous studies using 'Hass' avocado and its small fruit (SF) phenotype as a model showed that SF is limited by cell number, not by cell size. In an attempt to explore the molecular mechanisms regulating avocado fruit cell division, we isolated four distinct avocado cell proliferation-related genes and investigated their expression characteristics, comparing normal fruit (NF) and SF developmental patterns. Three cDNAs termed PaCYCA1, PaCYCB1 and PaPCNA, encoding two mitotic cyclins and a proliferating cell nuclear antigen (PCNA), were first isolated from young NF tissues. The accumulation of their transcripts was predominant in mitotically active organs, including young fruitlets, leaves and roots. Furthermore, a fourth full-length cDNA, designated Pafw2.2-like, encoding a FW2.2 (fruit-weight)-like protein, was isolated from SF tissues. FW2.2 is postulated to function as a negative regulator of cell division in tomato fruit. Remarkably, northern analysis revealed that the accumulation of the mitotic cyclins and of PCNA transcripts gradually decreased in NF tissues during growth, whereas in SF, their levels had already decreased at earlier stages of fruit development, concomitant with an earlier arrest of fruit cell division activity. In contrast, parallel sq-RT-PCR analysis showed that Pafw2.2-like mRNA accumulation was considerably higher in SF tissues than in the same NF tissues essentially at all examined stages of fruit growth. Together, our data suggest essential roles for the two mitotic cyclins genes and the PCNA gene in regulating avocado fruit development. Furthermore, the possibility that Pafw2.2-like acts as does fw2.2 in tomato, is discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A proposed conserved role for an avocado fw2.2-like gene as a negative regulator of fruit cell division

Dahan

Rosenfeld

Zadiranov

et al. 2010

Planta

View full text Add to dashboard Cite

show abstract

“…Bar: 0.1 gm. From Ehlers and van Bel (1999) 1986; Moore- Gordon et al 1998), this finding might indicate that the plugged plasmodesmata may become re-opened.…”

Section: Resultsmentioning

confidence: 92%

The formation of symplasmic domains by plugging of plasmodesmata: a general event in plant morphogenesis?

1999

View full text Add to dashboard Cite

The plasmodesmal network was examined in multicellular protoplast-derived calluses of the dicotyledon Solanum nigrum which had not yet formed any visible adventitious organs and in globular proembryogenic structures developed from scutellar calluses of the monocotyledon Molinia caerulea. Electron microscopical analyses revealed that both calluses and proembryos consisted of small, undifferentiated ceils. The interconnecting plasmodesmata at many cell interfaces were structurally inconspicuous in both systems; in particular cell walls, however, all plasmodesmata were occluded with an osmiophilic, dense material. As the blocking material was obviously tocated in the microchannels of the plasmodesmal cytoplasmic sleeves, the plugged plasmodesmata can be assumed to be nonfunctional. Thus, selective occlusion of all the plasmodesmata in specific cell walls resulted in the symplasmic disconnection of particular adjacent cells. Complex patterns of symplasmic continuity and discontinuity were established within the developing tissues. Some ceils or groups of cells were entirely symplasmically disconnected from the surrounding cells by plugged plasmodesmata and might function as independent domains. However, blockage of plasmodesmata was achieved by the surrounding cells rather than by those cells belonging to the isolated domains. The demarcation of symplasmic domains might be a general prerequisite for differential morphogenesis, since they were found to be established very early in the course of morphogenetic processes.

show abstract

“…Senescence of the seed coat and embryo abortion occur coincident with increased abscisic aldehyde oxidase but reduced indole acetaldehyde oxidase , and are stimulated by excess ABA but reversed when ABA is administered together with equimolar CK (Moore- Gordon et al 1998). Accumulation of ABA and IAA in seed tissue further distinguishes the small-fruit phenotype and supports the observation that low endogenous IAA correlates with rapid fruit growth in avocado (Gazit and Blumenfeld 1972).…”

Section: Discussionmentioning

confidence: 99%

Xanthine dehydrogenase and aldehyde oxidase impact plant hormone homeostasis and affect fruit size in ?Hass? avocado

Taylor¹,

Cowan²

2004

Journal of Plant Research

View full text Add to dashboard Cite

The contribution of xanthine dehydrogenase (XDH, EC 1.1.1.204) to fruit size was investigated using the normal and small-fruit variants of Persea americana Mill. cv. 'Hass'. Inhibition of XDH by treatment of normal fruit, in the linear phase of growth (phase II), with allopurinol (Allo) arrested fruit growth. Adenine (Ade), a less effective inhibitor of this enzyme, also arrested fruit growth when applied in phase II and slowed fruit growth when applied in phase III. A time-course study on the activity of XDH in mesocarp tissue from normal and small fruit showed that maximum activity occurred late in phase II and that the peak in activity was absent in mesocarp of the small fruit. Feeding Ade to growing fruit in phase III caused a transient decline in fruit growth (measured as change in fruit length). Thereafter, growth resumed although fruit size was irreversibly affected. Treatment of fruit with Ade and Ade-containing cytokinins altered activity of another molybdenum enzyme, aldehyde oxidase (EC 1.2.3.1). Cytokinin oxidase was induced by cytokinin and auxin. Purine catabolism via hypoxanthine/xanthine was operative in normal fruit and in mesocarp from the small-fruit variant and as expected, Allo treatment caused accumulation of xanthine and adenine. In the absence of an increase in XDH during growth of the small-fruit phenotype, low levels of Ade were interpreted as resulting from respiration-enhanced adenylate depletion. Stress and/or pathogen induction of the alternative oxidase pathway is proposed as a possible cause.

show abstract

Symplastic Solute Transport and Avocado Fruit Development: A Decline in Cytokinin/ABA Ratio is Related to Appearance of the Hass Small Fruit Variant

Cited by 36 publications

References 55 publications

A proposed conserved role for an avocado fw2.2-like gene as a negative regulator of fruit cell division

A proposed conserved role for an avocado fw2.2-like gene as a negative regulator of fruit cell division

The formation of symplasmic domains by plugging of plasmodesmata: a general event in plant morphogenesis?

Xanthine dehydrogenase and aldehyde oxidase impact plant hormone homeostasis and affect fruit size in ?Hass? avocado

Contact Info

Product

Resources

About