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Drought response of cowpea (Vigna unguiculata (L.) Walp.) landraces at leaf physiological and metabolite profile levels
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Orientador(es)
Resumo(s)
Drought threatens the world’s food production, particularly in Sub Saharan Africa low external input and rain
fed agricultural systems, where cowpea (Vigna unguiculata (L.) Walp.) is an important food crop. In the context of
growing concerns regarding climate changes implications on water availability, this study aimed at 1) to
evaluate the drought responses in cowpea landraces with contrasting drought tolerance levels (A55 – high
sensitivity; A80 - mild sensitivity; A116 - tolerant), 2) using an integrated physiological (leaf gas exchanges;
chlorophyll a fluorescence) and biochemical (photoprotective pigments; RuBisCO activity; primary metabolite
profiling) analysis to identify drought tolerance probes, in plants submitted to three water availability levels
(well-watered, WW; mild drought, MD; severe drought, SD). A116 plants maintained a better water status under
drought, what could justify the higher Pn and Pnmax values in MD, as well as higher photochemical use of energy
(reflected in the photochemical quenching (qL) and in the quantum yield of non-cyclic electron transport (Y(II))),
and the lower need of photoprotective thermal dissipation mechanisms (given by the non-photochemical
quenching (qN), and the quantum yield of regulated energy dissipation at photosystem PSII (Y(NPQ))), in MD and
SD plants. Greater declines of net (Pn) and potential (Pnmax) photosynthesis were observed in A55 plants, which
frequently showed significant impacts already under MD conditions in most parameters, whereas A80 usually
displayed and intermediate behaviour. Still, even A55 showed some acclimation response, regarding photoprotective
mechanisms associated with high contents of zeaxanthin, lutein, and carotenes, and high Y(NPQ), and
qN values, supporting the absence of an increase in the non-regulated energy dissipation at PSII (Y(NO) did not
increased) even in SD plants. Additionally, A55 was not significantly affected in RuBisCO activity, which showed
to be quite resilient in cowpea. A primary metabolite profiling, complemented with a partial least square discrimination
analysis (PLS-DA), allowed a better separation of A116 and A55 plants according to their degree of
drought tolerance. In response to drought, A116 showed the greatest accumulation of most responsive metabolites,
14 in total, with sucrose, fucose, urea, alanine and putrescine being exclusively increased in this genotype,
suggesting that they can be candidates as drought tolerance proxies. Other compounds, as proline, valine,
isoleucine (among amino acids), and rhamnose and raffinose (among sugars) showed close increase patterns
Descrição
Palavras-chave
photoprotection photosynthesis primary metabolome RuBisCO water deficit
Contexto Educativo
Citação
Gomes, Ana M.F.; Rodrigues, Ana P.; António, Carla; Rodrigues, Ana M.; Leitão, António E.; Batista-Santos, Paula; Nhantumbo, Nascimento; et al. "Drought response of cowpea (Vigna unguiculata (L.) Walp.) landraces at leaf physiological and metabolite profile levels". Environmental and Experimental Botany 175 (2020): 104060
Editora
Elsevier