Limits...
Buffering growth variations against water deficits through timely carbon usage.

Pantin F, Fanciullino AL, Massonnet C, Dauzat M, Simonneau T, Muller B - Front Plant Sci (2013)

Bottom Line: However, growth decreases faster than photosynthesis in response to drought, leading to increased carbohydrate stores under short-term or moderate water deficits.We show that high carbohydrate levels prevent excessive, hydraulic shrinkage of the fruit during days with high evaporative demand, most probably through osmotic adjustment.Together, our results contribute to the view that growing organs under moderate soil or air water deficit are not carbon starved, but use soluble carbohydrate in excess to partly release a hydromechanical limitation of growth.

View Article: PubMed Central - PubMed

Affiliation: UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, Institut de Biologie Intégrative des Plantes, Institut National de la Recherche Agronomique Montpellier, France.

ABSTRACT
Water stresses reduce plant growth but there is no consensus on whether carbon metabolism has any role in this reduction. Sugar starvation resulting from stomatal closure is often proposed as a cause of growth impairment under long-term or severe water deficits. However, growth decreases faster than photosynthesis in response to drought, leading to increased carbohydrate stores under short-term or moderate water deficits. Here, we addressed the question of the role of carbon availability on growth under moderate water deficits using two different systems. Firstly, we monitored the day/night pattern of leaf growth in Arabidopsis plants. We show that a moderate soil water deficit promotes leaf growth at night in mutants severely disrupted in their nighttime carbohydrate availability. This suggests that soil water deficit promotes carbon satiation. Secondly, we monitored the sub-hourly growth variations of clementine fruits in response to daily, natural fluctuations in air water deficit, and at contrasting source-sink balances obtained by defoliation. We show that high carbohydrate levels prevent excessive, hydraulic shrinkage of the fruit during days with high evaporative demand, most probably through osmotic adjustment. Together, our results contribute to the view that growing organs under moderate soil or air water deficit are not carbon starved, but use soluble carbohydrate in excess to partly release a hydromechanical limitation of growth.

No MeSH data available.


Related in: MedlinePlus

Developmental changes in clementine fruit growth and soluble sugar contents according to carbon availability. To probe the effect of carbon availability on fruit growth in field conditions, a defoliation treatment was applied on girdled fruiting branches from adult clementine trees to obtain three levels of leaf-to-fruit ratio: 5, 15, and 30 leaves per fruit. The leaf-to-fruit ratio 30 corresponds to conditions of non-limiting carbon availability, and was considered as the control (Poiroux-Gonord et al., 2013). For masses and carbohydrate measurements, five fruits per level of leaf-to-fruit ratio were collected regularly in the morning (10:00, local time) from September to March during the 2008–2009 season. Error bars are 95% confidence intervals.
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Figure 6: Developmental changes in clementine fruit growth and soluble sugar contents according to carbon availability. To probe the effect of carbon availability on fruit growth in field conditions, a defoliation treatment was applied on girdled fruiting branches from adult clementine trees to obtain three levels of leaf-to-fruit ratio: 5, 15, and 30 leaves per fruit. The leaf-to-fruit ratio 30 corresponds to conditions of non-limiting carbon availability, and was considered as the control (Poiroux-Gonord et al., 2013). For masses and carbohydrate measurements, five fruits per level of leaf-to-fruit ratio were collected regularly in the morning (10:00, local time) from September to March during the 2008–2009 season. Error bars are 95% confidence intervals.

Mentions: Carbon availability accelerated the onset of fruit color change (Figure 5), consistent with the idea that sugar availability promotes fruit ripening (Fanciullino et al., 2013). In the three treatments, full expansion and maturity were reached in the middle of December, as indicated by the plateau of fresh and dry weight, as well as sugar content (Figure 6). At later stages, these variables showed a moderate tendency to decrease, indicating over-maturity. These patterns are consistent with data from previous studies on clementine fruits growing under Mediterranean climate (Cercós et al., 2006; Tadeo et al., 2008). Whereas the defoliation treatment (performed in July) did not affect the seasonal pattern of fruit growth, it strongly affected fruit weight at maturity. For the 5 leaves per fruit treatment, a decrease of about 60 and 50% was observed in the pulp and peel fresh mass, respectively, when compared to the control. A less severe treatment also affected fruit mass, since a reduction in fresh mass up to 40% for both the pulp and the peel was observed at 15 leaves per fruit, when compared to the control. The fruit dry mass followed similar trends. The defoliation treatment also modified soluble sugar contents in pulp (Figure 6). The changes in soluble sugars were mainly due to variations in sucrose concentrations. The largest decrease in sucrose was observed for the five leaves per fruit treatment in November, with a reduction of 80% when expressed on a fresh weight basis.


Buffering growth variations against water deficits through timely carbon usage.

Pantin F, Fanciullino AL, Massonnet C, Dauzat M, Simonneau T, Muller B - Front Plant Sci (2013)

Developmental changes in clementine fruit growth and soluble sugar contents according to carbon availability. To probe the effect of carbon availability on fruit growth in field conditions, a defoliation treatment was applied on girdled fruiting branches from adult clementine trees to obtain three levels of leaf-to-fruit ratio: 5, 15, and 30 leaves per fruit. The leaf-to-fruit ratio 30 corresponds to conditions of non-limiting carbon availability, and was considered as the control (Poiroux-Gonord et al., 2013). For masses and carbohydrate measurements, five fruits per level of leaf-to-fruit ratio were collected regularly in the morning (10:00, local time) from September to March during the 2008–2009 season. Error bars are 95% confidence intervals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842905&req=5

Figure 6: Developmental changes in clementine fruit growth and soluble sugar contents according to carbon availability. To probe the effect of carbon availability on fruit growth in field conditions, a defoliation treatment was applied on girdled fruiting branches from adult clementine trees to obtain three levels of leaf-to-fruit ratio: 5, 15, and 30 leaves per fruit. The leaf-to-fruit ratio 30 corresponds to conditions of non-limiting carbon availability, and was considered as the control (Poiroux-Gonord et al., 2013). For masses and carbohydrate measurements, five fruits per level of leaf-to-fruit ratio were collected regularly in the morning (10:00, local time) from September to March during the 2008–2009 season. Error bars are 95% confidence intervals.
Mentions: Carbon availability accelerated the onset of fruit color change (Figure 5), consistent with the idea that sugar availability promotes fruit ripening (Fanciullino et al., 2013). In the three treatments, full expansion and maturity were reached in the middle of December, as indicated by the plateau of fresh and dry weight, as well as sugar content (Figure 6). At later stages, these variables showed a moderate tendency to decrease, indicating over-maturity. These patterns are consistent with data from previous studies on clementine fruits growing under Mediterranean climate (Cercós et al., 2006; Tadeo et al., 2008). Whereas the defoliation treatment (performed in July) did not affect the seasonal pattern of fruit growth, it strongly affected fruit weight at maturity. For the 5 leaves per fruit treatment, a decrease of about 60 and 50% was observed in the pulp and peel fresh mass, respectively, when compared to the control. A less severe treatment also affected fruit mass, since a reduction in fresh mass up to 40% for both the pulp and the peel was observed at 15 leaves per fruit, when compared to the control. The fruit dry mass followed similar trends. The defoliation treatment also modified soluble sugar contents in pulp (Figure 6). The changes in soluble sugars were mainly due to variations in sucrose concentrations. The largest decrease in sucrose was observed for the five leaves per fruit treatment in November, with a reduction of 80% when expressed on a fresh weight basis.

Bottom Line: However, growth decreases faster than photosynthesis in response to drought, leading to increased carbohydrate stores under short-term or moderate water deficits.We show that high carbohydrate levels prevent excessive, hydraulic shrinkage of the fruit during days with high evaporative demand, most probably through osmotic adjustment.Together, our results contribute to the view that growing organs under moderate soil or air water deficit are not carbon starved, but use soluble carbohydrate in excess to partly release a hydromechanical limitation of growth.

View Article: PubMed Central - PubMed

Affiliation: UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, Institut de Biologie Intégrative des Plantes, Institut National de la Recherche Agronomique Montpellier, France.

ABSTRACT
Water stresses reduce plant growth but there is no consensus on whether carbon metabolism has any role in this reduction. Sugar starvation resulting from stomatal closure is often proposed as a cause of growth impairment under long-term or severe water deficits. However, growth decreases faster than photosynthesis in response to drought, leading to increased carbohydrate stores under short-term or moderate water deficits. Here, we addressed the question of the role of carbon availability on growth under moderate water deficits using two different systems. Firstly, we monitored the day/night pattern of leaf growth in Arabidopsis plants. We show that a moderate soil water deficit promotes leaf growth at night in mutants severely disrupted in their nighttime carbohydrate availability. This suggests that soil water deficit promotes carbon satiation. Secondly, we monitored the sub-hourly growth variations of clementine fruits in response to daily, natural fluctuations in air water deficit, and at contrasting source-sink balances obtained by defoliation. We show that high carbohydrate levels prevent excessive, hydraulic shrinkage of the fruit during days with high evaporative demand, most probably through osmotic adjustment. Together, our results contribute to the view that growing organs under moderate soil or air water deficit are not carbon starved, but use soluble carbohydrate in excess to partly release a hydromechanical limitation of growth.

No MeSH data available.


Related in: MedlinePlus