Abstract
The growth of any plant is based on the enlargement of its constituent cells, which is driven by the uptake of water and is supported by the irreversible yielding of the cell wall. The latter process is driven by the effective turgor (Pi–Y), i.e., the excess turgor pressure beyond a critical yield threshold (Y), and it is limited by the physiological extensibility (Φ) of the cell wall, which serves as the coefficient of proportionality. It has been suggested that the plant growth hormone auxin increases Φ, with a resultant promotion of growth, while it does not affect Y (Cleland 1977). Any recorded change in Pi has been very small, if any, during the promotion of growth by auxin. We have developed a novel method called the “negative pressure jump” technique which enables us directly and very quickly to determine in vivo the adjustable yield threshold (Y′) with minimum perturbation of the elongation of the cell. The cell turgor is reduced to Y′ not osmotically but hydraulically by application of tension to xylem vessels from the drain of the xylem perfusion system. In the case of segments of hypocotyls of cowpea seedlings, auxin was found to reduced Y′ definitively (by 40–80 kPa). The contribution of this decrease is comparable in magnitude to that of the increase in Φ with respect to the promotion of growth. Once it has been decreased, Y′ is not affected by anoxia.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 4
Claim · model-written summary
Auxin reduced the adjustable yield threshold Y′ by 40–80 kPa in cowpea hypocotyl segments.
- Taxon
- cowpea
Vigna unguiculatat0 - Organ / stage
- hypocotylse2
- Treatment
- auxine2
- Outcome
- Y′e2
- Direction
- reducede2
- Value
- 40–80 kPae2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Segments of Cowpea Hypocotyl”
e2“In the case of segments of hypocotyls of cowpea seedlings, auxin was found to reduced Y′ definitively (by 40–80 kPa)”
Claim · model-written summary
The decrease in Y′ contributes to growth promotion in comparable magnitude to the increase in physiological extensibility.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- contribution of this decreasee3
- Comparator
- increase in Φe3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Segments of Cowpea Hypocotyl”
e3“The contribution of this decrease is comparable in magnitude to that of the increase in Φ with respect to the promotion of growth”
Claim · model-written summary
Once decreased, Y′ was not affected by anoxia.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- anoxiae4
- Outcome
- Y′e4
- Direction
- no_changeinferrede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Segments of Cowpea Hypocotyl”
e4“Once it has been decreased, Y′ is not affected by anoxia”
Claim · model-written summary
The negative pressure jump technique determines the adjustable yield threshold in vivo, comparing turgor reduction hydraulically rather than osmotically.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- adjustable yield threshold (Y′)e5
- Comparator
- osmoticallye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Segments of Cowpea Hypocotyl”
e1“The cell turgor is reduced to Y′ not osmotically but hydraulically by application of tension to xylem vessels from the drain of the xylem perfusion system”
e5“to determine in vivo the adjustable yield threshold (Y′)”