Relationship between volatile organic compounds released and growth of Cunninghamia lanceolata roots under low-phosphorus conditions

Abstract

To understand whether Chinese fir (Cunninghamia lanceolata) can conserve energy by reducing root volatiles to maintain growth under low phosphorus (P) conditions, we cultivated two half-sib families of Chinese fir that display high and low P use efficiency under conditions of normal P supply and total P deficiency. Gas chromatography-mass spectrometry analysis was used to determine the content of root volatiles, and the relationships among root volatiles and root growth index, P content, and distribution were analyzed. There were significantly fewer volatile organic compounds (VOCs) in the rhizosphere of these two fir families, No. 25 and No. 32, under P deficiency. Low P supply significantly promoted root growth in No. 25, increasing both average diameter and volume. A negative correlation was found between the volatiles and the increment of root average diameter and surface area. The belowground P distribution and the root to shoot P concentration (Pr/Ps) were higher in No. 25 than in No. 32. The total amount of VOCs, as well as the amount of 18 individual volatiles were positively correlated with P accumulation, aboveground P distribution, and belowground P distribution, but the opposite pattern was seen in Pr/Ps for family No. 25 seedlings. We conclude that the content and types of VOCs differ among the Chinese fir genotypes. Under low-P stress, the roots of Chinese fir reduce the release of VOCs to maintain seedling growth.

Keywords

• Cunninghamia lanceolata
• Low-phosphorus Stress
• Root Growth
• Root Volatile Organic Compounds
• Energy Balance