Potential of Saturnispora diversa MA as a postharvest biocontrol agent against anthracnose in loquat fruit

Abstract

A yeast strain (MA) was isolated from mango fruitand found to inhibit Colletotrichum gloeosporioides. The MA strain was subsequently identified as Saturnispora diversa based on 18S rRNA sequencingand a phylogenetic analysis. S. diversa, strain MA, effectively inhibited the growth and spore germination of C. gloeosporioides through competition of nutrients and space, as well as its ability to adhere to developing hyphae and spores of C. gloeosporioides. The inhibitory activity of MA was concentration dependent and increased as the concentration of MA was increased. Relative to the untreated control, fruit treated with S. diversa MA had a lower disease index and browning index, retained a higher degree of fruit firmness, and had increased levels of total soluble solids and protein, resulting in higher postharvest quality. S. diversa MA treatment decreased the accumulation of malondialdehyde (MDA) in loquat fruit, the generation superoxide anion (O2–.), and electrolyte leakage (an indicator of membrane injury). MA also enhanced the reactive oxygen species (ROS) scavenging enzyme activity, induced the activity of peroxidase (POD), and polyphenol oxidase (PPO), chitinase (CHI), all of which enhanced the disease resistance of loquat fruit to C. gloeosporioides. Our results demonstrate that S. diversa MA inhibits C. gloeosporioides and maintains the postharvest quality of loquat fruit. Based on these findings S. diversa MA represents an effective biocontrol agent that could be used to manage postharvest anthracnose in loquat.