Inter-ramet Photosynthate Translocation in Buffalograss under Differential Water Deficit Stress

Abstract

Understanding the effect of photosynthate translocation on the shoot density of buffalograss (Buchloe dactyloides) is very important to improve its turf quality. The objective of this study was to examine the effects of water stress on water transport patterns, endogenous hormone distribution and allocation, and photosynthate allocation for connected buffalograss ramets. Clones from a single parent plant of ‘Texoka’ buffalograss were used to generate three-ramet units. Ramets are members of a clone that are not independent from the parent plant. Each water stress treatment had one of the three ramets cultured in half-strength Hoagland solution with 30% of polyethylene glycol (PEG) of −1.2 MPa ψS, while the other two ramets were kept in half-strength Hoagland solution with ψS of −0.05 MPa. Results indicated that inter-ramet water integration happened when one of the connected ramets was under water stress. Transzeatin riboside content decreased in roots treated with PEG. Abscisic acid content increased in the roots of all treatments compared with the control. Water stress caused a reduction of indole-3-acetic acid content in shoots and roots, especially the ramet stressed. Gibberellic acid content in shoots and roots of all treatments increased compared with the control. Within the control, young ramets were sinks of photosynthate, but translocation toward older ramets was detected using 14CO2 label when the older ramet was under stress. Xylem, phloem, and parenchyma cells were probably involved in the physiological integration of these responses. Fates of connected clonal ramets of buffalograss were interrelated and the agronomic significance of this result should be evaluated further.