Effects of dark treatment and regular light recovery on the growth characteristics and regulation of chlorophyll in water dropwort

Abstract

Water dropwort is one of Apiaceae vegetables. Dark treatment could help to promote the degradation of chlorophyll and improve exterior quality and flavor of vegetable crops. Previous studies showed that the chlorophylls content would dramatically reduce in the dark, while the chlorophylls content would be promoted after regular light recovery. However, the understanding of the metabolic mechanism is limited in water dropwort. We treated the water dropwort under the dark at 0, 4, 8, 12, 16, 20 and 25 days, then, recovered with regular light for 2 and 4 days, respectively. The total of chlorophylls content gradually degraded and the chlorophyll a content decreased faster than chlorophyll b content during dark treatment in water dropwort. After regular light recovery, the expression levels of the genes related to chlorophyll synthesis and transformation were increased, while the expression levels of PPH and PAO degradation-related genes decreased gradually. The water dropwort sprouted a large amount of newborn petioles and leaf blades after 16 days dark treatment. After regular light recovery, chlorophyll content and gene expression level both increased slowly. The plants would maintain lower chlorophyll content for a long time and have a longer shelf-life after 16 days dark treatment. Taken together, the results suggested that the best time of blanching culture for water dropwort is 16 days. This study could help to elucidate the chlorophyll metabolism in water dropwort during blanching culture and provide new perspectives for screening the best time of dark treatment for water dropwort.