Postharvest salicylic acid treatment reduces storage rots in water-stressed but no unstressed sugarbeet roots

Authors: Fugate, Karen; FERRAREZE, JOCLEITA - Universidade Federal De Vicosa; Bolton, Melvin; DECKARD, EDWARD - North Dakota State University; Campbell, Larry; FINGER, FERNANDO - Universidade Federal De Vicosa

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2013
Publication Date: 7/1/2013
Citation: Fugate, K.K., Ferrareze, J.P., Bolton, M.D., Deckard, E.L., Campbell, L.G., Finger, F.L. 2013. Postharvest salicylic acid treatment reduces storage rots in water-stressed but not unstressed sugarbeet roots. Postharvest Biology and Technology. 85:162-166.

Interpretive Summary: Salicylic acid (SA) is a natural plant hormone that induces native plant defense responses. To determine whether SA could protect postharvest sugarbeet roots from storage rot, freshly harvested roots were treated with varying concentrations of SA and challenged with Botrytis cinerea, Penicillium claviforme, or Phoma betae, three pathogens that cause sugarbeet root storage rot. Roots were obtained from plants that received sufficient water or were water-stressed before harvest. SA treatments with roots from water-stressed plants were included since water-stress increases sugarbeet root susceptibility to storage rot and SA reduces the negative effects of drought for other plant species. SA had no effect on the severity of storage rot due to any of the pathogens when roots were obtained from plants that received sufficient water prior to harvest. However, SA reduced the severity of rot symptoms due to all three pathogens for roots from plants that were water stressed before harvest. SA reduced rot by reducing lesion size and reduced the amount of rotted tissue due to B. cinerea, P. claviforme, and P. betae by 54, 45, and 58%, respectively. The ability of SA to reduce rot severity in water-stressed roots but not in roots that received sufficient water before harvest suggests that SA alleviated the negative impact of water stress but did not directly protect sugarbeet roots against storage rots.

Technical Abstract: Exogenous application of salicylic acid (SA) reduces storage rots in a number of postharvest crops. SA’s ability to protect sugarbeet (Beta vulgaris L.) taproots from common storage rot pathogens, however, is unknown. To determine the potential of SA to reduce storage losses caused by three common causal organisms of sugarbeet storage rot, freshly harvested roots were treated with 0.01, 0.1, 1.0 or 10 mM SA, inoculated with Botrytis cinerea, Penicillium claviforme, or Phoma betae, and evaluated for the severity of rot symptoms after incubation at 20 °C and 90% relative humidity. Roots were obtained from plants that received sufficient water or were water-stressed prior to harvest. Roots from water-stressed plants were included since water-stress increases sugarbeet root susceptibility to storage rot and SA mitigates drought effects in other plant species. SA at concentrations of 0.01 to 10 mM had no effect on the severity of storage rot caused by B. cinerea, P. claviforme, or P. betae in roots from plants that received sufficient water prior to harvest. However, SA at these same concentrations reduced the severity of rot symptoms from all three pathogens in roots from plants that were water stressed prior to harvest. For water-stressed roots, all concentrations of SA produced statistically equivalent reductions in the weight of rotted tissue for each pathogen, and on average, SA reduced rot severity due to B. cinerea, P. claviforme, and P. betae by 54, 45, and 58%, respectively. SA reduced rot from all three pathogens by reducing lesion size, but did not affect the incidence of infection. The ability of SA to reduce rot severity in water-stressed roots, but not in roots that received sufficient water before harvest suggests that SA alleviated the negative impact of water stress but did not directly protect sugarbeet roots against storage rots.