Plant acclimatory responses to phosphate (Pi) starvation stress include the accumulation of carbohydrates, namely sugar and starch. However, whether altered endogenous carbohydrate profile could in turn affect plant Pi starvation responses remains widely unexplored. Here, two genes encoding the large and small subunits of an ADP‐glucose pyrophosphorylase (AGP) in rice (Oryza sativa), AGP Large Subunit 1 (AGPL1) and AGP Small Subunit 1 (AGPS1), were functionally characterized with regard to maintenance of phosphorus (P) homeostasis and regulation of Pi starvation signaling. AGPL1 and AGPS1 were both positively responsive to nitrogen (N) or Pi deprivation, and expressed in almost all the tissues except in the meristem and mature zones of root. AGPL1 and AGPS1 physically interacted in chloroplast, and catalyzed the rate‐limiting step of starch biosynthesis. Low‐N‐ (LN) and low‐Pi (LP)‐triggered starch accumulation in leaves was impaired in agpl1, agps1 and apgl1 agps1 mutants compared with the wild‐type plants. By contrast, mutation of AGPL1 and/or AGPS1 led to an increase in the content of the major sugar, sucrose, in leaf sheath and root under control and LN conditions. Moreover, the Pi accumulation was enhanced in the mutants under control and LN conditions, but not LP conditions. Notably, the LN‐induced suppression of Pi accumulation was compromised attributed to the mutation of AGPL1 and/or AGPS1. Furthermore, the increased Pi accumulation was accompanied by the specific suppression of OsSPX2 and activation of several Pi transporter genes. These results indicate that a balanced level of carbohydrates is vital for maintaining plant P homeostasis.

中文翻译：

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两个ADP葡萄糖焦磷酸化酶亚基OsAGPL1和OsAGPS1调节水稻中的磷稳态

植物对磷酸盐（Pi）饥饿胁迫的适应性反应包括碳水化合物的积累，即糖和淀粉。但是，是否改变内源碳水化合物谱反过来又会影响植物Pi的饥饿反应仍未得到广泛研究。在这里，在维持稻米的功能上，对两个基因进行了编码，该基因编码水稻（Oryza sativa）中ADP-葡萄糖焦磷酸化酶（AGP）的大亚基和小亚基，AGP大亚基1（AGPL1）和AGP小亚基1（AGPS1）。磷（P）稳态和Pi饥饿信号的调节。AGPL1和AGPS1对氮（N）或Pi剥夺均具有正响应，并且在除分生组织和成熟根区以外的几乎所有组织中均表达。AGPL1和AGPS1在叶绿体中发生物理相互作用，并催化淀粉生物合成的限速步骤。与野生型植物相比，agpl1，agps1和apgl1 agps1突变体损害了低N（LN）和低Pi（LP）触发的叶片中淀粉积累。相比之下，AGPL1和/或AGPS1的突变导致在对照和LN条件下，叶鞘和根中主要糖，蔗糖的含量增加。此外，在对照和LN条件下，但在LP条件下，突变体中的Pi积累增加。值得注意的是，LN诱导的Pi积累的抑制作用归因于AGPL1和/或AGPS1的突变。此外，增加的Pi积累伴随OsSPX2的特异性抑制和几个Pi转运蛋白基因的激活。这些结果表明，碳水化合物的平衡水平对于维持植物体内的P稳态至关重要。