CAAS makes progress in maize study
DATE:2015-09-17 SOURCE:MOA
According to a recent joint study by a research team on maize functional genome ofthe Biotechnology Research Institute of the Chinese Academy of Agricultural Sciences (CAAS) and the Institute of Plant Protection of CAAS, new progress has been made on analyzing maize indirect defense against herbivores- Terpene Synthase 10 expression.
Maize has been established as a model system to study the indirect plant defense against herbivores during the past two decades. When attacked by lepidopteran larvae, maize leaves emit a complex blend of volatiles mainly composed of sesquiterpenes to attract the natural enemies of herbivores. This is associated with a swift transcriptional induction of terpene synthases such as TPS10. However, the molecular components controlling the complex transcriptional reprogramming in this process are still obscure. By exploiting the finding that the maize TPS10 promoter retained its full responsiveness to herbivory in Arabidopsis, the study identified the -300 to -200 region of TPS10 promoter as both necessary and sufficient for its herbivore inducibility through 5' deletion mapping. A high-throughput screening of an Arabidopsis transcription factor library using this promoter region as the bait identified seven AP2/ERF family transcription factors. Among their close homologs in maize, EREB58 was the only gene responsive to herbivory, with a spatiotemporal expression pattern highly similar to that of TPS10. Meanwhile, EREB58 was also responsive to Jasmonate. In vivo and in vitro assays indicated that EREB58 promotes TPS10 expression by directly binding to the GCC-box within the -300 to -200 region of TPS10 promoter. Transgenic maize plants overexpressing EREB58 constitutivly over-accumulated TPS10 transcript and also (E)-β-farnesene and (E)-α-bergamotene, two major sesquiterpenes produced by TPS10. In contrast, jasmonate induction of TPS10 and its volatiles were abolished in EREB58-RNAi transgenic lines. These results in sum demonstrate that EREB58 is a positive regulator of sesquiterpene production by directly promoting TPS10 expression.
The study was published on-line on the latest issue of the well-known international journal The Plant Journal.
The study was funded by the National Natural Science Foundation of China.