大豆GmALMT基因家族在大豆适应低磷胁迫中的功能研究

Phosphorus (P) deficiency is a major factor limiting crop production. A potential mechanism to enhance utilization of sparingly soluble forms of this sparsely available element is the secretion of organic acids, such as malate from roots. Malate exudation is mainly mediated by the ALMT family in plants. In this study, a total of 34 GmALMT genes were identified in the soybean genome, with two distinct clades detected in the phylogenetic tree. Expression patterns diverged considerably among GmALMT genes in response to Pi starvation in leaves, roots and flowers, with expression altered by P availability in 26 of the 34 GmALMTs. One root specific member with expression enhanced by Pi-starvation, GmALMT5, was chosen for dissecting the role of ALMT in controlling malate exudation. Results showed that GmALMT5 is a root cell plasma membrane channel protein that mediates malate efflux. Furthermore, it was found that both growth and P concentration of transgenic Arabidopsis lines with GmALMT5 overexpression were significantly increased when sparingly soluble Ca-P was applied as the sole external P source. Taken together, these results suggest that soybean GmALMT proteins have diverse functions in P nutrition. Closer inspection revealed that one member, GmALMT5, might contribute to the utilization of sparingly soluble extracellular sources of P by soybean under P limited conditions