Inferring Roles in Defense from Metabolic Allocation of Rice Diterpenoids

Lu, Xuan
Zhang, Juan
Brown, Benjamin
Peters, Reuben
Li, Riqing
Rodríguez-Romero, Julio
Berasategui, Aileen
Liu, Bo
Xu, Meimei
Luo, Dangping
Pan, Zhiqiang
Baerson, Scott
Gershenzon, Jonathan
Li, Zhaohu
Sesma, Ane
Yang, Bing
Peters, Reuben
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Biochemistry, Biophysics and Molecular BiologyGenetics, Development and Cell Biology

Among their responses to microbial infection, plants deploy an arsenal of natural antibiotic products. Historically these have been identified on the basis of their antibiotic activity in vitro, which leaves open the question of their relevance to defense in planta. The vast majority of such natural products from the important crop plant rice (Oryza sativa) are diterpenoids whose biosynthesis proceeds via either ent- or syn-copalyl diphosphate (CPP) intermediates, which were isolated on the basis of their antibiotic activity against the fungal blast pathogen Magnaporthe oryzae. However, rice plants in which the gene for the syn-CPP synthase Os-CPS4 is knocked out do not exhibit increased susceptibility to M. oryzae. Here, we show that knocking out or knocking down Os-CPS4 actually decreases susceptibility to the bacterial leaf blight pathogen Xanthomonas oryzae. By contrast, genetic manipulation of the gene for the ent-CPP synthase Os-CPS2 alters susceptibility to both M. oryzae and X. oryzae. Despite the secretion of diterpenoids dependent on Os-CPS2 or Os-CPS4from roots, neither knockout exhibited significant changes in the composition of their rhizosphere bacterial communities. Nevertheless, rice plants allocate substantial metabolic resources toward syn- as well as ent-CPP derived diterpenoids upon infection/induction. Further investigation revealed that Os-CPS4 plays a role in fungal non-host disease resistance. Thus, examination of metabolic allocation provides important clues into physiological function.


This article is published as Lu, Xuan, Juan Zhang, Benjamin Brown, Riqing Li, Julio Rodríguez-Romero, Aileen Berasategui, Bo Liu et al. "Inferring Roles in Defense from Metabolic Allocation of Rice Diterpenoids." The Plant Cell 30 (2018): 1119-1131. doi: 10.1105/tpc.18.00205.