Abstract
Taro (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 efficiency (WUE), and biomass (B). The Δ13C-shoot content showed partially open stomata in all accessions, and significant 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 significantly 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.
Highlights
Variation of abscisic acid from taro whole‐plants subjected to water scarcity
A 12% decrease in the Abscisic acid (ABA)-corm was observed under drought, while a slight 4% increase of ABA was reported in the shoot
The present study showed ABA-shoot accumulation and ABA-corm decreased content in taro submitted to drought
Summary
Schott) is an important crop for food security in developing countries, as an important source of carbohydrates in the form of starch stored in the corms (Sharma et al 2016). In 2018, taro production in Africa alone reached almost 7.9 Mt, representing 74% of the worldwide production (FAOSTAT Statistical Database 2018). Taro requires nearly 2500 mm rainfall per year, which is considered a high-water volume to achieve optimal yields. As its productivity highly depends on water availability, this crop is more exposed to long periods of water shortage, regarding the expected events in climate change (Ganança et al 2018). Crop plants use abscisic acid (ABA), a sesquiterpene with an α,β-unsaturated ketone in the ring and a conjugated diene side-chain, as an important isoprenoid stress-induced
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