School of Life Science, Shandong University, Jinan, Shandong, 250100, China.
BMC Plant Biol. 2012 Jun 14;12:89. doi: 10.1186/1471-2229-12-89.
Phosphorus (P) is an essential macronutrient for all living organisms. Maize (Zea mays) is an important human food, animal feed and energy crop throughout the world, and enormous quantities of phosphate fertilizer are required for maize cultivation. Thus, it is important to improve the efficiency of the use of phosphate fertilizer for maize.
In this study, we analyzed the maize root response to phosphate starvation and performed a transcriptomic analysis of the 1.0-1.5 cm lateral root primordium zone. In the growth of plants, the root-to-shoot ratio (R/L) was reduced in both low-phosphate (LP) and sufficient-phosphate (SP) solutions, but the ratio (R/L) exhibited by the plants in the LP solution was higher than that of the SP plants. The growth of primary roots was slightly promoted after 6 days of phosphate starvation, whereas the numbers of lateral roots and lateral root primordia were significantly reduced, and these differences were increased when associated with the stress caused by phosphate starvation. Among the results of a transcriptomic analysis of the maize lateral root primordium zone, there were two highlights: 1) auxin signaling participated in the response and the modification of root morphology under low-phosphate conditions, which may occur via local concentration changes due to the biosynthesis and transport of auxin, and LOB domain proteins may be an intermediary between auxin signaling and root morphology; and 2) the observed retardation of lateral root development was the result of co-regulation of DNA replication, transcription, protein synthesis and degradation and cell growth.
These results indicated that maize roots show a different growth pattern than Arabidopsis under low-phosphate conditions, as the latter species has been observed to halt primary root growth when the root tip comes into contact with low-phosphate media. Moreover, our findings enrich our understanding of plant responses to phosphate deficits and of root morphogenesis in maize.
磷（P）是所有生物的必需大量营养素。玉米（Zea mays）是全世界重要的人类食品、动物饲料和能源作物，玉米种植需要大量的磷酸盐肥料。因此，提高磷酸盐肥料在玉米中的利用效率非常重要。
本研究分析了玉米根对磷酸盐饥饿的反应，并对 1.0-1.5 厘米侧根原基区进行了转录组分析。在植物生长过程中，根冠比（R/L）在低磷（LP）和充足磷（SP）溶液中均降低，但 LP 溶液中植物的 R/L 比值高于 SP 植物。磷酸盐饥饿 6 天后，初级根的生长略有促进，而侧根和侧根原基的数量明显减少，当与磷酸盐饥饿引起的胁迫相关时，这些差异会增加。在玉米侧根原基区转录组分析的结果中，有两个亮点：1）生长素信号参与了低磷条件下的响应和根形态的修饰，这可能是由于生长素的生物合成和运输导致局部浓度变化引起的，LOB 结构域蛋白可能是生长素信号和根形态之间的中介；2）观察到侧根发育的延迟是由于 DNA 复制、转录、蛋白质合成和降解以及细胞生长的共同调节所致。
这些结果表明，与拟南芥相比，玉米根在低磷条件下表现出不同的生长模式，因为当根尖接触低磷介质时，后者的主要根生长会停止。此外，我们的研究结果丰富了对植物对磷亏缺的反应以及玉米根形态发生的认识。
