Gibberellic Acid Regulates Cell Wall Extensibility in Wheat (<i>Triticum aestivum</i> L.)

Keyes, G. J.; Sorrells, Mark E.; Setter, Tim L.

doi:10.1104/pp.92.1.242

Cited by 62 publications

(25 citation statements)

References 21 publications

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“…In longer-term experiments with rht (tall) wheat grown at 22 ~ C, applied GA3 increased wall extensibility in the leaf elongation zone (Keyes et al 1990) indicating that, even under these conditions, endogenous GAs may constrain the rate of leaf expansion. In the present experiments, the absolute responsiveness of the rht3 line to applied GA~ was greater at 10 ~ C than at 20 ~ C and, since endogenous GAt (plus GA3) content was similar, it seems reasonable to conclude that endogenous GAs may be more sensitive regulators of leaf expansion at lower than at higher temperatures.…”

Section: Discussionmentioning

confidence: 96%

“…In a separate study with wheat lines grown at 18-20 ~ C, both epidermal cell length and the rate of leaf expansion were proportional to the dosage of Rhtl and Rht2 semidwarfing alleles (Keyes et al 1989). Irreversible extensibility of immature leaf segments also declined with increasing Rht gene dose and was correlated positively with mature sheath length (Keyes et al 1990). It was reported recently that the more potent Rht3 dwarfing gene caused a reduction in both epidermal cell length and cell number per leaf (Hoogendoorn et al 1990).…”

Section: Introductionmentioning

confidence: 95%

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Gibberellins and leaf expansion in near-isogenic wheat lines containing Rht1 and Rht3 dwarfing alleles

Appleford

Lenton

1991

Planta

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In near-isogenic lines of winter wheat (Triticum aestivum L. cv. Maris Huntsman) grown at 20° C under long days the reduced-height genes, Rht1 (semi-dwarf) and Rht3 (dwarf) reduced the rate of extension of leaf 2 by 12% and 52%, respectively, compared with corresponding rht (tall) lines. Lowering the growing temperature from 20° to 10° C reduced the rate of linear extension of leaf 2 by 2.5-fold (60% reduction) in the rht3 line but by only 1.6-fold (36% reduction) in the Rht3 line. For both genotypes, the duration of leaf expansion was greater at the lower temperature so that final leaf length was reduced by only 35% in the rht3 line and was similar in the Rht3 line at both temperatures. Seedlings of the rht3 (tall) line growing at 20° C responded positively to root-applied gibberellin A1 (GA1) in the range 1-10 μM GA1; there was a linear increase in sheath length of leaf 1 whereas the Rht3 (dwarf) line remained unresponsive. Gibberellins A1, 3, 4, 8, 19, 20, 29, 34, 44 and 53 were identified by full-scan gas chromatography-mass spectrometry in aseptically grown 4-d-old shoots of the Rht3 line. In 12-d-old seedlings grown at 20° C, there were fourfold and 24-fold increases in the concentration of GA1 in the leaf expansion zone of Rht1 and Rht3 lines, respectively, compared with corresponding rht lines. Although GA3 was present at a similar level to GA1 in the rht3 (tall) line it accumulated only fivefold in the Rht3 (dwarf) line. The steady-state pool sizes of endogenous GAs were GA19 ≫ GA20 = GA1 in the GA-responsive rht3 line whereas in the GA non-responsive Rht3 line the content of GA19≈ GA20 ⋘ GA1. It is proposed that one of the consequences of GA1 action is suppression of GA19-oxidase activity such that the conversion of GA19 to GA20 becomes a rate-limiting step on the pathway to GA1 in GA-responsive lines. In the GA-non-responsive Rht lines it is suggested that GA19 oxidase is not downregulated to the same extent and GA1 accumulates before the next rate-limiting step on the pathway, its 2β-hydroxylation to GA8. The steady-state pool sizes of GA19, 20, 1, 3 and 8 were similar in developmentally equivalent tissues of the rht3 (tall) line growing at 10° C and 20° C despite a 2.5-fold difference in the rate of leaf expansion. In contrast, in the Rht3 (dwarf) line, the extent of accumulation of GA1 reflected the severity of the phenotype at the two temperatures with slower growing tissues accumulating less, not more, GA1. These results are interpreted as supporting the proposed model of regulation of the GA-biosynthetic pathway rather than previous suggestions that GA1 accumulates in GA-insensitive dwarfs as a consequence of reduced growth rates.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 95%

Gibberellins and leaf expansion in near-isogenic wheat lines containing Rht1 and Rht3 dwarfing alleles

Appleford

Lenton

1991

Planta

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“…For example, Stoddart & Lloyd (1986) found that, in wheat meristems, the minimum temperature for cell expansion was lowered by direct applications of GAg, and Keyes, Sorrells & Setter (1990), with the aid of dwarf mutants of wheat, showed that GA was involved in determining the extensibility of leaf sheath cells. The higher rates of cell and leaf extension in long days can, therefore, be interpreted in terms of increased cell wall extensibility along the long axis of the leaf, although it is possible that the yield threshold pressure could also be affected (Tyree & Jarvis, 1982).…”

Section: The Role Of Gibberellins In the Photoperiodic Stimulationmentioning

confidence: 99%

The influence of photoperiod on the dry matter production of grasses and cereals

Hay

1990

New Phytologist

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summary Photoperiod can affect the growth and development of grasses and cereals in three distinct ways: by providing a cue for the start of the reproductive phase, by modifying the rate of reproductive development once established, and by causing changes in the rate of leaf area expansion and of dry‐matter production which are not necessarily related to reproduction. This review, which draws heavily on work with grasses from high latitudes in Scandinavia, deals mainly with this third influence of photoperiod, documenting the range of observed effects on plant development and physiology, and drawing results from other systems to help in exploring the underlying mechanisms. It is difficult to devise experimental treatments which differ only in daylength but involve realistic daily inputs of photosynthetically active radiation (PAR), to avoid possible interactions with shading responses. In the natural environment, photoperiod is confounded with the supply of radiant energy, and the spectral composition of solar radiation at the beginning and end of each day varies with latitude. It is concluded that the use of daylit phytotron chambers with daylength extension by low‐irradiance incandescent lamps is the most practical solution to this complex problem. A survey of experiments conducted under realistic irradiances showed that exposure of plants of a range of temperate and high‐latitude grasses and cereals to longer days, without increasing the supply of PAR, resulted in substantial increases (up to 200%) in dry‐matter production, and even greater increases in leaf area. These effects, which were common to vegetative and reproductive plants, tended to be most marked at lower temperatures. Growth analysis showed that, in general, this enhancement was a consequence of increases in leaf area ratio which, in turn, were caused by increases in specific leaf area rather than in leaf weight ratio. Higher rates of dry‐matter production were, therefore, a result of improved interception of PAR, although, in many experiments, net assimilation rates were lower. Photoperiodic stimulation of growth was generally associated with an unchanged or increased shoot: root ratio, reduction in the number of tillers per plant, unchanged numbers of leaves per tiller, but longer leaf sheaths and blades. Increases in blade length, in turn, were associated with increases in epidermal cell length, although there is also evidence of increased cell division, and in tissue succulence. It was concluded that photoperiodic stimulation of growth is a consequence of a positive feedback system, in which the additional photosynthate from the first leaves which develop under long days is invested in progressively larger leaves. Studies of CO2 exchange rates suggest that the observed decreases in net assimilation rate could be explained in terms of the number of cells or the amount of chlorophyll per unit of leaf area. The fact that increased growth results from increased interception of PAR indicates that, in swards, the effect will only be shown in spring...

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“…The phytohormone GA also participates in stem elongation and wall extensibility in plants [27] but whether the induction of the (i---)3,1--)4)-fl-gluc~_nase isoenzyme El gene by GA3 in young leaves (Fig. 1) is related to this effect remains unknown.…”

Section: Discussionmentioning

confidence: 99%

Barley (1→3,1→4)‐β‐glucanase isoenzyme EI gene expression is mediated by auxin and gibberellic acid

Slakeski

1992

FEBS Letters

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Treatment of young barley leaves with indole acetic acid (IAA) or gibberellic acid (GA3) results in a dramatic increase in levels of (1→3,1→4)‐β‐glucanase isoenzyme El transcripts. In young roots of comparable age, levels of isoenzyme El mRNA are high; IAA inhibits expression while GA3 has no effect on mRNA levels. The addition of both abscisic acid and GA3 to leaves, roots and aleurone layers leads to higher levels of (1→3,1→4)‐β‐glucanase isoenzyme El mRNA than is found with Ga3 alone. Little or no expression of (1→3,1→4)‐β‐glucanase isoenzyme EII is detected in vegetative tissues, but in isolated aleurone layers GA3 enhances levels of isoenzyme EII transcripts, as does IAA. Thus, the two barley (1→3,1→4)‐β‐glucanase genes respond quite differently to phytohormone treatment, depending on the tissue and its stage of development.

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Gibberellic Acid Regulates Cell Wall Extensibility in Wheat (Triticum aestivum L.)

Cited by 62 publications

References 21 publications

Gibberellins and leaf expansion in near-isogenic wheat lines containing Rht1 and Rht3 dwarfing alleles

Gibberellins and leaf expansion in near-isogenic wheat lines containing Rht1 and Rht3 dwarfing alleles

The influence of photoperiod on the dry matter production of grasses and cereals

Barley (1→3,1→4)‐β‐glucanase isoenzyme EI gene expression is mediated by auxin and gibberellic acid

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