Differential roles of and in trade-off between plant growth and drought tolerance.

Due to global climate change, drought is emerging as a major threat to plant growth and agricultural productivity. Abscisic acid (ABA) has been implicated in plant drought tolerance, however, its retarding effects on plant growth cannot be ignored. The reactions catalyzed by 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) proteins are critical steps within the isoprenoid biosynthesis in plants. Here, five () and two () genes were identified from genome. Based on multiple assays including the phylogeny, acting element, expression pattern, and subcellular localization, and genes might be potential candidates controlling the isoprenoid biosynthesis. Intriguingly, transgenic plants resulted in drought tolerance but retardant growth, while transgenic plants exhibited both enhanced drought tolerance and increased growth. By comparison of -carotene, chlorophyll, abscisic acid (ABA) and gibberellin 3 (GA) contents in wild-type and transgenic plants, the absolute contents and (or) altered GA/ABA levels were suggested to be responsible for the balance between drought tolerance and plant growth. The transcriptome of transgenic plants suggested that the transcript levels of key genes, such as , (), () and etc, involved with chlorophyll, -carotene, ABA and GA biosynthesis were induced and their contents increased accordingly. Collectively, the trade-off effect induced by was associated with redesigning architecture in phytohormone homeostasis and thus was highlighted for future breeding purposes.