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30. Wheat Oxylipins in Response to Aphids, CO2 and Nitrogen Regimes

Author

Cascant-Vilaplana, Mari Merce, primary, Viteritti, Eduardo, additional, Sadras, Víctor, additional, Medina, Sonia, additional, Sánchez-Iglesias, María Puerto, additional, Oger, Camille, additional, Galano, Jean-Marie, additional, Durand, Thierry, additional, Gabaldón, José Antonio, additional, Taylor, Julian, additional, Ferreres, Federico, additional, Sergi, Manuel, additional, and Gil-Izquierdo, Angel, additional

Published
2023
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36. Wheat yield is not causally related to the duration of the growing season

Author

Slafer, Gustavo A., Savin, Roxana, and Sadras, Víctor O.

Subjects
Critical period, Grain number, Phenology, Anthesis
Abstract

A common conceptual model for crop growth analysis assumes biomass is proportional to the accumulation of radiation intercepted by the canopy during the growing season, and yield is the product of biomass and harvest index. This model assumes that biomass and harvest index are independent, and that biomass has the same value for yield across developmental stages; here we focus on the latter assumption. A corollary of this model is that yield and duration of the growing season are causally related. In this article, we analyse the evidence for and against this causal relationship. We use both a physiological perspective and agronomic evidence to challenge this causality. An alternative, phenology-focused model is outlined that is based on the following principles: crops accommodate environmental variation through grain number, grain number is defined in a species-specific critical developmental period, and grain number is a function of three traits in the critical period: duration, growth rate, and partitioning to reproduction. Against this framework, we analyse dual purpose wheat, where a substantial part of the biomass is removed, effectively shortening the growing season, with little or no effect on yield; timing of nitrogen fertilisation, where delayed application reduces the growth rate early in the season, with little or no effect on yield; and the correlation between season length and yield of winter wheat and spring wheat - wheat yield in Southern Chile, with a sowing-to-maturity season of ∼ 5 months, could be as high as that of winter wheat in the UK, with a sowing-to-maturity season of ∼ 10 months. Physiological principles and agronomic evidence support the conclusion that the duration of, and growth rate and partitioning during the critical period, rather than the duration of the growing season, are the drivers of wheat yield. This study had not specific funding, but many sources have funded the research of the authors on yield physiology over the years. Most recent grants include projects funded by the State Research Agency of Spain (RTI2018–096213-B-100, PID2021–127415OB-I00) and by SARDI-GRDC bilateral (DAS00166_BA).

Published
2023

42. Wheat Oxylipins in Response to Aphids, CO 2 and Nitrogen Regimes.

Author

Cascant-Vilaplana, Mari Merce, Viteritti, Eduardo, Sadras, Víctor, Medina, Sonia, Sánchez-Iglesias, María Puerto, Oger, Camille, Galano, Jean-Marie, Durand, Thierry, Gabaldón, José Antonio, Taylor, Julian, Ferreres, Federico, Sergi, Manuel, and Gil-Izquierdo, Angel

Subjects
APHIDS, OXYLIPINS, RHOPALOSIPHUM padi, CARBON dioxide, GREENBUG, WHEAT
Abstract

Wheat is critical for food security, and is challenged by biotic stresses, chiefly aphids and the viruses they transmit. The objective of this study was to determine whether aphids feeding on wheat could trigger a defensive plant reaction to oxidative stress that involved plant oxylipins. Plants were grown in chambers with a factorial combination of two nitrogen rates (100% N vs. 20% N in Hoagland solution), and two concentrations of CO2 (400 vs. 700 ppm). The seedlings were challenged with Rhopalosiphum padi or Sitobion avenae for 8 h. Wheat leaves produced phytoprostanes (PhytoPs) of the F1 series, and three types of phytofurans (PhytoFs): ent-16(RS)-13-epi-ST-Δ14-9-PhytoF, ent-16(RS)-9-epi-ST-Δ14-10-PhytoF and ent-9(RS)-12-epi-ST-Δ10-13-PhytoF. The oxylipin levels varied with aphids, but not with other experimental sources of variation. Both Rhopalosiphum padi and Sitobion avenae reduced the concentrations of ent-16(RS)-13-epi-ST-Δ14-9-PhytoF and ent-16(RS)-9-epi-ST-Δ14-10-PhytoF in relation to controls, but had little or no effect on PhytoPs. Our results are consistent with aphids affecting the levels of PUFAs (oxylipin precursors), which decreased the levels of PhytoFs in wheat leaves. Therefore, PhytoFs could be postulated as an early indicator of aphid hosting for this plant species. This is the first report on the quantification of non-enzymatic PhytoFs and PhytoPs in wheat leaves in response to aphids. [ABSTRACT FROM AUTHOR]

Published
2023
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