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Terminal drought-tolerant pearl millet [Pennisetum glaucum (L.) R. Br.] have high leaf ABA and limit transpiration at high vapour pressure deficit.

Kholová J, Hash CT, Kumar PL, Yadav RS, Kocová M, Vadez V - J. Exp. Bot. (2010)

Bottom Line: Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range.Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences.This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

View Article: PubMed Central - PubMed

Affiliation: International Crops Research Institute for the Semi-Arid Tropics, Patancheru 502 324, Andhra Pradesh, India.

ABSTRACT
It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

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Related in: MedlinePlus

ABA content of four pearl millet testcross hybrids [H 77/833-2, ICMB 841-P3 (sensitive), PRLT 2/89-33, 863B-P2 (tolerant)] grown in well-watered (WW) and water stress (WS) conditions and sampled at FTSW=0.25 at the vegetative stage (a) and at FTSW=0.30 at the reproductive stage (b). Experiments were conducted in January 2007 (Experiments 1 and 2). Values are the means (±SE) of six replicate plants per treatment and genotype. Genotypic means with the same letters above the bar within a treatment are not significantly different. Letters below the x-axis are for the genotypic comparison of means between treatments.
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fig1: ABA content of four pearl millet testcross hybrids [H 77/833-2, ICMB 841-P3 (sensitive), PRLT 2/89-33, 863B-P2 (tolerant)] grown in well-watered (WW) and water stress (WS) conditions and sampled at FTSW=0.25 at the vegetative stage (a) and at FTSW=0.30 at the reproductive stage (b). Experiments were conducted in January 2007 (Experiments 1 and 2). Values are the means (±SE) of six replicate plants per treatment and genotype. Genotypic means with the same letters above the bar within a treatment are not significantly different. Letters below the x-axis are for the genotypic comparison of means between treatments.

Mentions: Across the two experiments, PRLT 2/89-33 (tolerant) generally had significantly higher leaf ABA than H 77/833-2 [Fig. 1a, b (P <0.1 under WS in Experiment 5; Fig. 2)], except under WS conditions during the reproductive stage in Experiment 1 (Fig. 1b). The ABA level of all three NIL-QTLs under WW conditions was significantly higher than in H 77/833-2 and similar to that of PRLT 2/89-33 (Fig. 2). Under WS conditions, the ABA content of drought-stressed plants did not discriminate NIL-QTLs from sensitive H 77/833-2 as well as it did under WW conditions, and ABA content was higher in ICMR 01029 and ICMR 01031 than in H 77/833-2.


Terminal drought-tolerant pearl millet [Pennisetum glaucum (L.) R. Br.] have high leaf ABA and limit transpiration at high vapour pressure deficit.

Kholová J, Hash CT, Kumar PL, Yadav RS, Kocová M, Vadez V - J. Exp. Bot. (2010)

ABA content of four pearl millet testcross hybrids [H 77/833-2, ICMB 841-P3 (sensitive), PRLT 2/89-33, 863B-P2 (tolerant)] grown in well-watered (WW) and water stress (WS) conditions and sampled at FTSW=0.25 at the vegetative stage (a) and at FTSW=0.30 at the reproductive stage (b). Experiments were conducted in January 2007 (Experiments 1 and 2). Values are the means (±SE) of six replicate plants per treatment and genotype. Genotypic means with the same letters above the bar within a treatment are not significantly different. Letters below the x-axis are for the genotypic comparison of means between treatments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2837262&req=5

fig1: ABA content of four pearl millet testcross hybrids [H 77/833-2, ICMB 841-P3 (sensitive), PRLT 2/89-33, 863B-P2 (tolerant)] grown in well-watered (WW) and water stress (WS) conditions and sampled at FTSW=0.25 at the vegetative stage (a) and at FTSW=0.30 at the reproductive stage (b). Experiments were conducted in January 2007 (Experiments 1 and 2). Values are the means (±SE) of six replicate plants per treatment and genotype. Genotypic means with the same letters above the bar within a treatment are not significantly different. Letters below the x-axis are for the genotypic comparison of means between treatments.
Mentions: Across the two experiments, PRLT 2/89-33 (tolerant) generally had significantly higher leaf ABA than H 77/833-2 [Fig. 1a, b (P <0.1 under WS in Experiment 5; Fig. 2)], except under WS conditions during the reproductive stage in Experiment 1 (Fig. 1b). The ABA level of all three NIL-QTLs under WW conditions was significantly higher than in H 77/833-2 and similar to that of PRLT 2/89-33 (Fig. 2). Under WS conditions, the ABA content of drought-stressed plants did not discriminate NIL-QTLs from sensitive H 77/833-2 as well as it did under WW conditions, and ABA content was higher in ICMR 01029 and ICMR 01031 than in H 77/833-2.

Bottom Line: Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range.Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences.This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

View Article: PubMed Central - PubMed

Affiliation: International Crops Research Institute for the Semi-Arid Tropics, Patancheru 502 324, Andhra Pradesh, India.

ABSTRACT
It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

Show MeSH
Related in: MedlinePlus