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- Drought avoidance and phenotypic flexibility of sweet potato (Ipomoea batatas (L.) Lam.) under water scarcity conditionsPublication . Gouveia, Carla S. S.; Ganança, José F. T.; Nóbrega, Humberto G. M.; Freitas, José G. R.; Lebot, Vincent; Carvalho, Miguel Â. A. Pinheiro deSweet potato (Ipomoea batatas (L.) Lam.) is an important staple food in several regions of the world. Water scarcity is the most devastating abiotic stress, with a great impact on crop productivity, food security, and subsistence. Drought restricts the nutrient intake and transport into the plant. Tolerant crops have morphological mechanisms of drought avoidance and/or phenotypic flexibility, showing also good water and nutrient efficiency. However, that information is scarce for sweet potato, which is usually based on physiological traits of plant productivity. Here, we show the physiological responses of eight sweet potato accessions subjected to a 3 months’ drought period, by recording their differences for nutrient and leaf chlorophyll content, biomass and stress level. Our results showed that the differences in water use efficiency (WUE, +68.1%), chlorophyll content index (CCI, -5.3%), total plant biomass (TPB, -55.4%), nutrient efficiency (NER, +38.1%) and nutrient harvest index (NHI, +2.9%) where significantly correlated with the water regime. The water shortage led to a drought avoidance response, with TPB loss in all accessions. Distinct phenotypic flexibility responses were also recorded and explained by the root:shoot ratio (R:S) and stress index (SI) variation of the storage root and shoot growth. This information could be relevant for the development of sweet potato breeding programs, adapting this crop to climate change.
- Involvement of abscisic acid and other stress indicators in taro (Colocasia esculenta (L.) Schott) response to drought conditionsPublication . Gouveia, Carla S. S.; Ganança, José F. T.; Slaski, Jan J.; Lebot, Vincent; Carvalho, Miguel Â. A. Pinheiro deTaro (Colocasia esculenta (L.) Schott) is a staple food and represents an important food security role in most tropical regions. It is, unfortunately, susceptible to prolonged drought conditions. Abscisic acid (ABA) is a well-documented stress-induced phytohormone that tolerant crops usually accumulate in leaves to induce stomatal closure, preventing water loss through inhibition of transpiration. Hitherto, exists very scarce information regarding the ABA role in taro response to drought. Here, we determined the ABA content in the shoots and corms of taro subjected to seven months of water scarcity and linked ABA to other drought resilience traits, including carbon isotopic discrimination (Δ13C), oxalic acid (OA), chlorophyll content index (CCI), water use efciency (WUE), and biomass (B). The Δ13C-shoot content showed partially open stomata in all accessions, and signifcant correlation with Δ13C-corm, CCI, and WUE. The osmotically active OA-shoot decrease seemed not to interfere with the stomatal aperture. The tolerant accessions subjected to drought stress had higher B-corm, ABA shoot, Δ13C-shoot, CCI, OA, and WUE. However, the observed under drought conditions increase of ABA in the shoots, and its decrease in the corms were not signifcantly correlated, nor with other traits, suggesting that ABA was not the main regulator of taro physiological processes under stress. The information gained should be considered in breeding programs to predict taro’s response to climate change.