@article{fdi:010081702,
  title = {{P}earl millet ({P}ennisetum glaucum) contrasting for the transpiration response to vapour pressure deficit also differ in their dependence on the symplastic and apoplastic water transport pathways},
  author = {{T}haranya, {M}. and {S}ivasakthi, {K}. and {B}arzana, {G}. and {K}holová, {J}. and {T}hirunalasundari, {T}.  and {V}adez, {V}incent},
  editor = {},
  language = {{ENG}},
  abstract = {{G}enotypic differences in transpiration rate responses to high vapour pressure deficit ({VPD}) was earlier reported. {H}ere we tested the hypothesis that this limitation could relate to different degrees of dependence on the apoplastic (spaces between cells), and symplastic water transport pathways (through cells via aquaporin-facilitated transport), which are known to have different hydraulic conductivities. {T}he low transpiration rate ({T}r) genotype {PRLT} 2/89/33 either restricted its transpiration under high {VPD}, or was more sensitive to {VPD} than {H}77/833-2, when grown hydroponically or in soil. {T}he slope of the transpiration response to an ascending series of {VPD} was lower in whole plants than in de-rooted shoots. {I}n addition, the transpiration response of detached leaves to moderately high {VPD} (2.67 k{P}a), normalised against leaves exposed to constant {VPD} (1.27 k{P}a), was similar in low and high {T}r genotypes. {T}his suggested that roots hydraulics were a substantial limitation to water flow in pearl millet, especially under high {VPD}. {T}he dependence on the apoplastic and symplastic water transport pathways was investigated by assessing the transpiration response of plants treated with inhibitors specific to the {AQP}-mediated symplastic pathway ({A}g{NO}3 and {H}2{O}2) and to the apoplastic pathway (precipitates of {C}u({F}e({CN})6) or {C}u({C}u{F}e({CN})6)). {W}hen {C}u{SO}4 alone was used, {C}u ions caused an inhibition of transpiration in both genotypes and more so in {H}77/833-2. {T}he transpiration of high {T}r {H}77/833-2 was decreased more by {AQP} inhibitors under low {VPD} (1.8 k{P}a) than in {PRLT} 2/89/33, whereas under high {VPD} (4.2 k{P}a), the transpiration of {PRLT} 2/89/33 was decreased more by {AQP} inhibitors than in {H}77/833-2. {T}he transpiration rate of detached leaves from {H}77/833-2 when treated with {A}g{NO}3 decreased more than in {PRLT} 2/89/33. {A}lthough the root hydraulic conductivity of both genotypes was similar, it decreased more upon the application of a symplastic inhibitor in {H}77/833-2. {T}he transpiration of low {T}r {PRLT} 2/89/33 was decreased more by apoplastic inhibitors under both low and high {VPD}. {T}hen the hydraulic conductivity decreased more upon the application of an apoplastic inhibitor in {PRLT} 2/89/33. {I}n conclusion, both pathways contributed to water transport, and their contribution varied with environmental conditions and genotypes. {R}oots were a main source of hydraulic limitation in these genotypes of pearl millet, although a leaf limitation was not excluded. {T}he similarity between genotypes in root hydraulic conductivity under normal conditions also suggests changes in this conductivity upon changes in the evaporative demand. {T}he low {T}r genotype depended more on the apoplastic pathway for water transport, whereas the high {T}r genotype depended on both pathway, may be by "tuning-up" the symplastic pathway under high transpiration demand, very likely via the involvement of aquaporins},
  keywords = {{ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{F}unctional {P}lant {B}iology},
  volume = {45},
  numero = {7},
  pages = {719--736},
  ISSN = {1445-4408},
  year = {2018},
  DOI = {10.1071/{FP}17161},
  URL = {https://www.documentation.ird.fr/hor/fdi:010081702},
}