背景回顾：Phosphate (Pi) limitation represents a primary constraint on crop production. To better cope with Pi deficiency stress, plants have evolved multiple adaptive mechanisms for phosphorus acquisition and utilization, including the alteration of growth and the activation of Pi starvation signaling. 

提出问题：However, how these strategies are coordinated remains largely unknown. 

主要发现：Here, we found that the alternative splicing (AS) of REGULATOR OF LEAF INCLINATION 1 (RLI1) in rice (Oryza sativa) produces two protein isoforms: RLI1a, containing MYB DNA binding domain; and RLI1b, containing both MYB and coiled-coil (CC) domains. 

结果1-RLI1a功能：The absence of a CC domain in RLI1a enables it to activate broader target genes than RLI1b. RLI1a, but not RLI1b, regulates both brassinolide (BL) biosynthesis and signaling by directly activating BL-biosynthesis and signaling genes. Both RLI1a and RLI1b modulate Pi starvation signaling.

结果2-RLI1与PHR2：RLI1 and PHOSPHATE STARVATION RESPONSE 2 function redundantly to regulate Pi starvation signaling and growth in response to Pi deficiency. 

结果3-演化上的保守机制：Furthermore, the AS of RLI1-related genes to produce two isoforms for growth and Pi signaling is widely present in both dicots and monocots. 

结论：Together, these findings indicate that the AS of RLI1 is an important and functionally conserved strategy to orchestrate Pi starvation signaling and growth to help plants adapt to Pi-limitation stress.

 摘 要 

磷（Pi）限制是作物生产的一个主要限制因素。为了更好地应对缺磷胁迫，植物已经演化出多种磷获取和利用的适应机制，包括生长的改变和磷饥饿信号的激活。然而，我们仍不清楚植物如何具体协调这些策略。本文中，作者发现水稻RLI1基因的可变剪接会产生两种蛋白异构体：一个是含有MYB DNA结合域的RLI1a；另一个是包含MYB和coiled-coil（CC）结构域的RLI1b蛋白。RLI1a蛋白缺失了CC结构域，导致该蛋白比RLI1b能够激活更多的靶基因。RLI1a能够直接激活油菜素内酯生物合成和信号转导相关基因的表达，从而调控油菜素内酯的生物合成和信号转导，但是RLI1b不具有该功能。RLI1a和RLI1b都能够调节磷饥饿信号。RLI1和磷饥饿响应蛋白PHR2的在响应磷缺乏时，调节磷饥饿信号和植物生长方面存在功能冗余。此外，在单、双子叶植物中都均存在通过RLI1相关基因的可变剪切，产生两个作用于植物生长和磷信号的异构体。综上，本文的研究结果表明，RLI1的可变剪切是被子植物一种比较重要且保守的策略，用以磷饥饿信号和植物生长之间的协调，最终帮助植物适应缺磷胁迫。