Anaerobic metabolism in roots of Kentucky bluegrass in response to short-term waterlogging alone and in combination with high temperatures

Abstract

Waterlogging often occurs simultaneously with high temperatures during summer. The objective of this study was to characterize anaerobic metabolism and transcript abundance of fermentative enzymes in roots of Kentucky bluegrass (Poa pratensis L.) in response to short-term waterlogging and high temperature stresses. Grasses were subjected to four treatments: (1) well-drained under normal temperature (20/15°C, day/night; control); (2) waterlogging under normal temperature (WL); (3) well-drained under high temperature (35/30°C, day/night; HT); and (4) waterlogging under high temperature (WL + HT). Greater reductions in leaf elongation rate and shoot dry mass were observed under WL + HT than either stress alone. Root water-soluble carbohydrate concentration decreased 45% and 46% at 3 and 5 days of WL + HT, respectively, compared to the control. At 5 days, activities of root alcohol dehydrogenase increased 93% and 90% and lactate dehydrogenase increased 95% and 98% under WL and WL + HT, respectively, compared to the control. Transcript abundance of ADH and PDC genes in the roots were not or only slightly shown under the control or HT conditions but were induced by WL or WL + HT, particularly under WL. The results indicated that short-term WL + HT induced root anaerobic metabolism in a similar way to WL alone but had more severe effects on leaf growth and root WSC than did WL in Kentucky bluegrass.