Abstract
Previous work showed that the concentration of proline (Pro) increases greatly in the primary root tip of maize (Zea mays L.) at low water potentials ([psi]w). It was also shown that the maintenance of root elongation at low [psi]w depends on increased levels of abscisic acid (ABA). In this study we have assessed whether ABA is required for the increase in Pro concentration. Seedlings were grown in vermiculite of various [psi]w, and endogenous ABA levels were decreased using either fluridone (FLU) or the vp5 mutant to inhibit carotenoid (and ABA) synthesis. In both treatments, Pro concentrations at low [psi]w were substantially decreased throughout the apical centimeter, which encompassed the elongation zone. Pro concentrations in FLU-treated roots were restored by addition of 7 [mu]M ABA to the vermiculite, which raised the internal ABA content to the level in untreated roots at the same [psi]w. Pro and water content profiles were combined with published growth-velocity distributions to calculate the distribution of net Pro and water deposition rates using the continuity equation. At a [psi]w of -1.6 MPa, the rate of Pro deposition in the root tip was decreased by 75% in FLU-treated compared to untreated roots. FLU treatment increased root diameter and, therefore, water content per unit length, but water deposition rates decreased due to the dominant influence of reduced longitudinal expansion. Thus, the decrease in Pro concentration was attributable entirely to the decrease in Pro deposition. The results demonstrate that increased ABA is required for high rates of Pro deposition and, thereby, high Pro concentrations in the growing region of maize primary roots at low [psi]w.
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Claims 6
Claim · model-written summary
Fluridone and vp5 substantially decreased proline concentrations in maize root tips at low water potential.
- Organ / stage
- apical centimetere0
- Treatment
- both treatmentse0
- Outcome
- Pro concentrationse0
- Direction
- decreasede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both treatments, Pro concentrations at low [psi]w were substantially decreased throughout the apical centimeter, which encompassed the elongation zone.”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
Claim · model-written summary
Adding ABA restored proline concentrations in fluridone-treated roots.
- Organ / stage
- rootse0
- Treatment
- addition of 7 [mu]M ABAe0
- Outcome
- Pro concentrationse0
- Direction
- restorede0
- Comparator
- FLU-treated rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pro concentrations in FLU-treated roots were restored by addition of 7 [mu]M ABA to the vermiculite, which raised the internal ABA content to the level in untreated roots at the same [psi]w.”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
Claim · model-written summary
At -1.6 MPa, fluridone lowered proline deposition in maize root tips by 75% relative to untreated roots.
- Organ / stage
- root tipe0
- Treatment
- FLU-treatede0
- Outcome
- rate of Pro depositione0
- Direction
- decreasede0
- Value
- 75%e0
- Comparator
- untreated rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At a [psi]w of -1.6 MPa, the rate of Pro deposition in the root tip was decreased by 75% in FLU-treated compared to untreated roots.”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
Claim · model-written summary
Fluridone increased maize root diameter and water content per unit length.
- Treatment
- FLU treatmente0
- Outcome
- root diameter and, therefore, water content per unit lengthe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FLU treatment increased root diameter and, therefore, water content per unit length”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
Claim · model-written summary
Fluridone decreased water deposition rates because longitudinal expansion was reduced.
- Treatment
- FLU treatmente0
- Outcome
- water deposition ratese0
- Direction
- decreasede0
- Qualifier
- reduced longitudinal expansione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FLU treatment increased root diameter and, therefore, water content per unit length, but water deposition rates decreased due to the dominant influence of reduced longitudinal expansion.”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
Claim · model-written summary
The reduced proline concentration was attributed entirely to reduced proline deposition.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Thus, the decrease in Pro concentration was attributable entirely to the decrease in Pro deposition.”
t0“Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)”
The same questions in other papers
Fluridone · growth · Zea mays (maize)Positive and negative results
3 papers in the same direction as this paper · 5 in the opposite direction
- negative
- negative
- negative
5 papers more in this group
See all 9 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.