First report on GABA (gamma-amino butyric acid) regulation of carbohydrates under wheat stripe rust in India

Carbohydrates and gamma-amino butyric acid (GABA) have not been studied under the stress of stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) in wheat. Wheat cultivars PBW725 (resistant) and HD2967 (susceptible) were compared at 1, 2 and 4 d of GABA, Pst, and GABA + Pst sprayed to 30-d of seedling growth. Starch was hydrolyzed, and levels of sugars and proteins improved over time of infection in PBW725 however HD2967 improved under GABA + Pst. Proline increased while GABA decreased over the time of infection in HD2967. Progressive increase of diamine oxidase and glutamate decarboxylase was seen in PBW725 during infection. Protease levels became low at 4 d of infection but improved under GABA + Pst in HD2967. Protein carbonyls increased in HD2967 only under Pst but decreased under GABA + Pst. Results concluded that GABA is an essential regulator of carbohydrates under stripe rust. Sustained response over time of infection may be important for resistance.