Root metaxylem area influences drought tolerance and transpiration in pearl millet in a soil texture dependent manner

Affortit, P.; Faye, A.; Jones, D. H.; Benson, E.; Sine, B.; Burridge, J.; Ndoye, S.; Barry, L.; Moukouanga, D.; Barnard, S.; Bhosale, R.; Pridmore, T.; Gantet, P.; Vadez, V.; Cubry, P.; Kane, N. A.; Bennett, M. J.; Atkinson, J. J.; Laplaze, L.; Wells, D. M.; Grondin, A.

doi:10.1101/2024.11.09.622826

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bioRxiv · 10.1101/2024.11.09.622826

Root metaxylem area influences drought tolerance and transpiration in pearl millet in a soil texture dependent manner

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Abstract

O_LIPearl millet is a key cereal for food security in drylands but its yield is strongly impacted by drought. We investigated how root anatomical traits contribute to mitigating the effects of vegetative drought stress in pearl millet. C_LIO_LIWe examined associations between root anatomical traits and agronomical performance in a pearl millet diversity panel under irrigated and vegetative drought stress treatments in field trials. The impact of associated anatomical traits on transpiration was assessed using subpanels grown in different soil within a greenhouse. C_LIO_LIIn the field, total metaxylem area was positively correlated with grain weight and its maintenance under drought. In the greenhouse, genotypes with larger metaxylem area grown in sandy soil exhibited a consumerist water use strategy under irrigation, which shifted to a conservative strategy under drought. Water savings was mediated by transpiration restriction under high evaporative demand. This mechanism was dependent on soil hydraulics as it was not observed in peat soil with higher hydraulic conductivity upon soil drying. C_LIO_LIWe propose that water savings under drought, mediated by large metaxylem area and its interaction with soil hydraulics, help mitigate vegetative drought stress. Our findings highlight the role of soil hydraulic properties in shaping plant hydraulics and drought tolerance. C_LI

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Affortit, P., Faye, A., Jones, D. H., Benson, E., Sine, B., Burridge, J., Ndoye, S., Barry, L., Moukouanga, D., Barnard, S., Bhosale, R., Pridmore, T., Gantet, P., Vadez, V., Cubry, P., Kane, N. A., Bennett, M. J., Atkinson, J. J., Laplaze, L., Wells, D. M., Grondin, A.. 2024-11-11. Root metaxylem area influences drought tolerance and transpiration in pearl millet in a soil texture dependent manner. https://doi.org/10.1101/2024.11.09.622826

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