Conferring drought resistant traits to crops is one of the major aims of current breeding programs in response to global climate changes. We previously showed that exogenous application of acetic acid to roots of various plants could induce increased survivability under subsequent drought stress conditions, but details of the metabolism of exogenously applied acetic acid, and the nature of signals induced by its application, have not been unveiled. In this study, we show that rice rapidly induces jasmonate signaling upon application of acetic acid, resulting in physiological changes similar to those seen under drought. The major metabolite of the exogenously applied acetic acid in xylem sap was determined as glutamine—a common and abundant component of xylem sap—indicating that acetic acid is not the direct agent inducing the observed physiological responses in shoots. Expression of drought-responsive genes in shoot under subsequent drought conditions was attenuated by acetic acid treatment. These data suggest that acetic acid activates root-to-shoot jasmonate signals that partially overlap with those induced by drought, thereby conferring an acclimated state on shoots prior to subsequent drought.

Rice seedlings (Oryza sativa) that have died from drought cannot be rescued by watering afterward, but pre-treatment with exogenous acetic acid enabled the plants to produce shoots again after being watered (hereinafter referred to as "drought resilience"). To elucidate the metabolism of acetic acid, we treated rice plants with 13 C-labeled acetic acid and traced 13 C-labeled metabolites using LC-MS and 13 C-NMR techniques. The LC-MS and 13 C-NMR spectral data of the root extracts indicated that the acetic acid treatment was absorbed into the plants and then was metabolized to gamma-aminobutyric acid (GABA) by glutamic acid decarboxylase (GAD). GABA accumulation in the roots took place in advance of that in the shoots, and the survival rate against drought stress increased in proportion to the amount of GABA accumulated in the shoots. Therefore, GABA accumulation in shoots may be a key step in drought resilience induced by the acetic acid treatment.

Tempura coating that is fried with wheat flour batter should have crispy texture; however, the gluten present in wheat prevents the development of a favorable texture. Thus, we prepared tempura using barley flour, buckwheat flour, or Job's tears flour, which do not form gluten structure. Their quality and palatability were compared to that of normal rice and waxy rice, which are gluten-free grains, in addition to wheat flour. We focused on the changes over time of texture which was an issue with tempura. We hypothesized that the changes in the texture involved moisture absorption from the ingredients, and aimed to reveal the difference in the changes over time by using grain flours. Changes in crispiness and moisture content were different based on the grain flour. Wheat, normal rice, and buckwheat tempura coating absorbed moisture from ingredients and lose crispiness over time. Waxy rice and barley tempura absorbed ingredients moisture only in the tempura coating near ingredients, and there was no change in the crispiness of that surface. Alternatively, Job's tears tempura coating did not change crispiness and moisture content even after 30 min of frying. Therefore, it would be beneficial to use appropriate tempura coating material based on the occasion.