Studies in the Morphogenesis of Leaves

Ashby, Eric

doi:10.1111/j.1469-8137.1948.tb05099.x

Cited by 64 publications

(16 citation statements)

References 6 publications

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“…The results indicate that an unknown factor(s) underlying heteroblasty has an important role in the regulation of the cell number and cell size of leaves. Although an increase in cell number and a decrease in cell size in leaves at higher nodes have been observed in several species (Ashby, 1948;Granier and Tardieu, 1998;Cnops et al, 2004;Cookson et al, 2007), the cause of this phenomenon was unclear until the present study. In this report, we propose that miR156 and SPL genes are involved in heteroblastic change of cell number and size (see below).…”

Section: Discussionmentioning

confidence: 46%

“…In Arabidopsis thaliana (Arabidopsis, hereafter), lamina size, leaf length/width ratio, petiole length, serration number, and production of abaxial trichomes change in relation to heteroblasty. Cell number and cell size in leaves might also change with heteroblasty, as an increase in cell number and a decrease in cell size in higher node leaves is observed in various species (Ashby, 1948;Granier and Tardieu, 1998;Cnops et al, 2004;Cookson et al, 2007). However, reduced water availability caused by water deprivation to leaves at lower nodes, or diffusive inhibitory signals from lower leaves were previously thought to account for the reduction in cell size in leaves on higher nodes (Ashby, 1948); whether this phenomenon is physiological or genetically controlled remains to be answered.…”

Section: Introductionmentioning

confidence: 99%

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Themore and smaller cellsmutants ofArabidopsis thalianaidentify novel roles forSQUAMOSA PROMOTER BINDING PROTEIN-LIKEgenes in the control of heteroblasty

et al. 2009

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Regulation of cell number and cell size is essential for controlling the shape and size of leaves. Here, we report a novel class of Arabidopsis thaliana mutants, more and smaller cells 1 (msc1)-msc3, which have increased cell number and decreased cell size in leaves. msc1 has a miR156-resistant mutation in the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 15 (SPL15) gene. msc2 and msc3 are new alleles of paused and squint mutants, respectively. All msc mutants showed accelerated heteroblasty, a phenomenon in which several morphological traits of leaves change along with phase change. Consistent with this finding, in the wild type, leaves at higher nodes (adult leaves) also have increased cell number and reduced cell size compared with those at lower nodes (juvenile leaves). These facts indicate that precocious acquisition of adult leaf characteristics in the msc mutants may cause alterations in the number and size of cells, and that heteroblasty plays an important role in the regulation of cell number and size. In agreement with this suggestion, such heteroblasty-associated changes in cell number and size are severely inhibited by the constitutive overexpression of miR156 and are promoted by the elevated expression of miR156-insensitive forms of SPL genes. By contrast, rdr6, sgs3, zip, arf3 and arf4 mutations, which affect progression of heteroblasty, had little or no effect on number or size of cells. These results suggest that cell number and size are mainly regulated by an SPL-dependent pathway rather than by a tasiR-ARF-dependent pathway.

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Section: Discussionmentioning

confidence: 46%

Section: Introductionmentioning

confidence: 99%

Themore and smaller cellsmutants ofArabidopsis thalianaidentify novel roles forSQUAMOSA PROMOTER BINDING PROTEIN-LIKEgenes in the control of heteroblasty

et al. 2009

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“…Both epidermal cell number and area vary in leaves depending on the rank of their emergence. A decline in cell area with increasing leaf position is commonly observed in plants, whereas epidermal cell number is generally increased as reported in Ipomoea (Ashby, 1948), sunflower (Helianthus annuus; Granier and Tardieu, 1998), and Arabidopsis (Cookson et al, 2007). Epidermal cell area distributions between different individual leaves have been discussed in terms of whole plant control mechanisms with a role for floral development (Ashby, 1948).…”

Section: Discussion Both Epidermal Cell Number and Cell Area Are Contmentioning

confidence: 99%

“…Regulation of individual leaf development seems even more complex because there is additional evidence that it is also controlled, to some extent, at the whole plant level. For example, the decline in cell area in leaves with increasing leaf position in a plant depends on whole plant control mechanisms related to floral transition as shown by floral bud removal or changes in daylength delaying or accelerating flowering (Ashby, 1948;Cookson et al, 2007).…”

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confidence: 99%

Combined Genetic and Modeling Approaches Reveal That Epidermal Cell Area and Number in Leaves Are Controlled by Leaf and Plant Developmental Processes in Arabidopsis

et al. 2008

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Both leaf production and leaf expansion are tightly linked to cell expansion and cell division, but the functional relationships between all these variables are not clearly established. To get insight into these relationships, a quantitative genetic analysis was performed in 118 recombinant inbred lines derived from a cross between the Landsberg erecta and Antwerp accessions and was combined with a structural equation modeling approach. Main effects and epistatic interactions at the quantitative trait locus (QTL) level were detected for rosette area, rosette leaf number, leaf 6 area, epidermal cell area and number. A QTL at ERECTA marker (ER) controlled cell expansion and cell division, in interaction with two other QTLs at SNP295 and SNP21 markers. Moreover, both the screening for marker association involved in the variation of the relationships between leaf growth variables and the test of alternative functional models by structural equation modeling revealed that the allelic value at ER controlled epidermal cell area and epidermal cell number in a leaf. These effects are driven both by a whole plant mechanism associated with leaf production and by a single leaf mechanism associated with leaf expansion. The complex effects of the QTL at ER were validated in selected heterogeneous inbred families. The ERECTA gene, which is mutated in the Landsberg erecta parental line, was found to be a putative candidate responsible for these mapped effects by phenotyping mutants of this gene at the cellular level. Together, these results give insight into the complex determination of leaf epidermal cell number and area.

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“…This could not be due to a genetic control of cell size, because final areas differed in leaves 8 and 16 analyzed here, but also in a series of similar analyses carried out in the field and in the greenhouse (C. Granier and F. Tardieu, unpublished data). Change in final cell area with position on the stem was also observed by Ashby (1948). Common final cell area was probably due to the fact that changes in RER and RDR were strictly parallel in all zones of a leaf, but the period with maintained RER and declining RDR was shorter in leaf 16 than in leaf 8.…”

Section: Discussionmentioning

confidence: 73%

Spatial and Temporal Analyses of Expansion and Cell Cycle in Sunflower Leaves1

1998

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We have investigated the spatial distributions of expansion and cell cycle in sunflower (Helianthus annuus L.) leaves located at two positions on the stem, from leaf initiation to the end of expansion. Relative expansion rate (RER) was analyzed by following the deformation of a grid drawn on the lamina; relative division rate (RDR) and flow-cytometry data were obtained in four zones perpendicular to the midrib. Calculations for determining in situ durations of the cell cycle and of S-G2-M in the epidermis are proposed. Area and cell number of a given leaf zone increased exponentially during the first two-thirds of the development duration. RER and RDR were constant and similar in all zones of a leaf and in all studied leaves during this period. Reduction in RER occurred afterward with a tip-to-base gradient and lagged behind that of RDR by 4 to 5 d in all zones. After a long period of constancy, cell-cycle duration increased rapidly and simultaneously within a leaf zone, with cells blocked in the G0-G1 phase of the cycle. Cells that began their cycle after the end of the period with exponential increase in cell number could not finish it, suggesting that they abruptly lost their competence to cross a critical step of the cycle. Differences in area and in cell number among zones of a leaf and among leaves of a plant essentially depended on the timing of two events, cessation of exponential expansion and of exponential division.

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Studies in the Morphogenesis of Leaves

Cited by 64 publications

References 6 publications

Themore and smaller cellsmutants ofArabidopsis thalianaidentify novel roles forSQUAMOSA PROMOTER BINDING PROTEIN-LIKEgenes in the control of heteroblasty

Themore and smaller cellsmutants ofArabidopsis thalianaidentify novel roles forSQUAMOSA PROMOTER BINDING PROTEIN-LIKEgenes in the control of heteroblasty

Combined Genetic and Modeling Approaches Reveal That Epidermal Cell Area and Number in Leaves Are Controlled by Leaf and Plant Developmental Processes in Arabidopsis

Spatial and Temporal Analyses of Expansion and Cell Cycle in Sunflower Leaves1

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