Clonal integration alters metabolic non-structural carbohydrate processes of a dwarf bamboo under negatively correlated light and soil water conditions

Abstract

Generally spoken that light and soil water conditions within patches often negatively correlate, significantly affecting the growth of clonal plants. But the role of clonal integration in modulating carbohydrate metabolism of paired ramets under heterogeneous environments remains unclear. Hence the initial research is performed focusing on water and carbohydrate sharing among ramets under heterogeneous environments and its impact on non-structural carbohydrate (NSC) accumulation and conversion of whole clonal system. Connected and disconnected clonal fragments of dwarf bamboo were planted in four heterogeneous environments differing in patch contrast with negatively correlated light and soil water. Photosynthetic capacity, NSC content, and its metabolic characteristics were measured, and the effects of water and NSC sharing on the performance of paired bamboo ramets were also analyzed. Leaf photosynthetic rate (P_n) and NSC content of shade ramets ranged from 7.06 to 8.56μmol·m⁻²·s⁻¹, 140.85–176.12 mg.g⁻¹, and those for unshaded ramets were 3.98 ∼6.97μmol·m⁻²·s⁻¹ and 129.58–170.81 mg.g⁻¹, respectively. Rhizome connection significantly decreased leaf P_n, NSC, chlorophyll, and RuBisCo in shaded ramets but increased these parameters in unshaded ramets. High water contrast led to higher leaf P_n, NSC, chlorophyll, and RuBisCo activity in both ramets with rhizome connection. Moderately shaded treatments (50 % shading) increased leaf P_n, NSC, and chlorophyll content in both shaded and unshaded ramets with rhizome connection. Rhizome connection significantly decreased the activities of sucrose synthase (SS), sucrose phosphate synthase (SPS), and amylase in shaded ramets, but increased SS, SPS, amylase, and invertase (INV) in unshaded ramets. Water sharing promoted both leaf NSC and P_n in ramets growing under high light but low soil water conditions when connected to ramets growing under shading but higher soil water conditions. The mutual conversion of starch into sugar between paired ramets enhanced the fitness of the entire clonal system. Obviously the findings provide new insights into the adaptive strategies of dwarf bamboo to drought and shading stress through physiological integration (water and NSC sharing) and NSC conversion, which could help predict the impact of climate change on bamboo growth and productivity.