Abstract
As drought is increasingly frequent in the context of climate change it is a major constraint for crop growth and yield. The ability of plants to maintain their yield in response to drought depends not only on their ability to tolerate drought, but also on their capacity to subsequently recover. Post-stress recovery can indeed be decisive for drought resilience and yield stability. Pea (Pisum sativum), as a legume, has the capacity to fix atmospheric nitrogen through its symbiotic interaction with soil bacteria within root nodules. Biological nitrogen fixation is highly sensitive to drought which can impact plant nitrogen nutrition and growth. Our study aimed at dynamically evaluating whether the control of plant N status after drought could affect nodulated pea plant’s ability to recover. Two pea genotypes, Puget and Kayanne, displaying different drought resilience abilities were compared for their capacity to tolerate to, and to recover from, a 2-weeks water-deficit period applied before flowering. Physiological processes were studied in this time-series experiment using a conceptual structure–function analysis framework focusing on whole plant carbon, nitrogen, and water fluxes combined to two 13CO2 and 15N2 labeling experiments. While Puget showed a yield decrease compared to well-watered plants, Kayanne was able to maintain its yield. During the recovery period, genotype-dependent strategies were observed. The analysis of the synchronization of carbon, nitrogen, and water related traits dynamics during the recovery period and at the whole plant level, revealed that plant growth recovery was tightly linked to N nutrition. In Puget, the initiation of new nodules after water deficit was delayed compared to control plants, and additional nodules developed, while in Kayanne the formation of nodules was both rapidly and strictly re-adjusted to plant growth needs, allowing a full recovery. Our study suggested that a rapid re-launch of N acquisition, associated with a fine-tuning of nodule formation during the post-stress period is essential for efficient drought resilience in pea leading to yield stability.
Highlights
Pea (Pisum sativum L.) produces seeds rich in proteins, which can be used for both feed and food
Our study aimed at evaluating whether plant N nutrition could affect nodulated pea plant’s ability to recover after a drought period
The major difference between the two genotypes under optimal watering conditions was that Kayanne allocated less biomass to underground organs than Puget (Supplementary Table S1), suggesting that different mechanisms in resource allocation and use could be established during drought tolerance and postdrought recovery
Summary
Pea (Pisum sativum L.) produces seeds rich in proteins (about 25%, Reichert and MacKenzie, 1982), which can be used for both feed and food. Pea does not require nitrogen fertilizer for its growth, making it an economic and environmental friendly crop that can play an important role in sustainable agriculture (Graham, 2003; Jensen and HauggaardNielsen, 2003). This particular feature is due to legumes’ unique ability to fix atmospheric dinitrogen (N2) thanks to a symbiosis with soil bacteria (type Rhizobia) inside specific root structures called nodules. This results in the induction of synchronous and transient waves of nodulations in the root system
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