Transcriptome profiling of the spl5 mutant reveals that SPL5 has a negative role in the biosynthesis of serotonin for rice disease resistance

Abstract

BackgroundRice mutant, spl5 (spotted leaf 5), has spontaneous hypersensitive-like lesions on its leaves and shows enhanced resistance to pathogens, indicating that SPL5 plays a role in programmed cell death (PCD) and disease resistance. To understand the molecular mechanism of SPL5 gene, we investigated the transcriptome profiles of the spl5 mutant leaves with few lesions (FL) and leaves with many lesions (ML) compared to the wild-type (WT) leaves respectively by microarray.ResultsThe data from microarray revealed that 243 and 896 candidate genes (Fold change ≥ 3.0) were up- or down-regulated in the spl5-FL and spl5-ML, respectively, and a large number of these genes involved in biotic defense responses or reactive oxygen species (ROS) metabolism. Interestingly, according to our microarray and real-time PCR assays, the expressions of a transcription factor OsWRKY14 and genes responsible for the biosynthesis of serotonin, anthranilate synthase (AS), indole-3-glycerolphosphate synthase (IGPS), tryptophan synthase (TS) and tryptophan decarboxylase (TDC) were significantly up-regulated in the spl5 mutant. It has been reported previously that TS and TDC expressions are regulated by OsWRKY14 in rice, which raises the possibility that OsWRKY14 regulates serotonin production through the up-regulation of TS and TDC. Our HPLC analysis further confirmed that serotonin levels were higher in the leaves of spl5 mutant than that in WT.ConclusionsSince the serotonin plays a critical role in inducing disease-resistance, the increased serotonin level may contribute, at least partly, to the disease resistance in spl5. The SPL5 gene may act as a negative regulatory factor activating the serotonin metabolic pathway, and these results might provide a new insight into the spl5-induced defense response mechanisms in plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0052-7) contains supplementary material, which is available to authorized users.

The Multivesicular Bodies (MVBs)-Localized AAA ATPase LRD6-6 Inhibits Immunity and Cell Death Likely through Regulating MVBs-Mediated Vesicular Trafficking in Rice

“…Indeed, we found that expression of the genes aroA and aroC , required for biosynthesis of chorismate from shikimate [ 72 , 73 ], obviously increased in the lrd6-6 mutant ( Fig 9A ). Because chorismate is required for biosynthesis of both serotonin and lignin [ 74 , 75 ], the increased expression of aroA and aroC would lead to accumulation of the antimicrobial metabolites, serotonin and lignin. We then found that expression of the downstream genes essential for respective biosynthesis of serotonin and lignin initiated from chorismate (for biosynthesis of serotonin: As , Igps , Ts and Tdc ; for biosynthesis of lignin: Pal , Ptal , 4Cl , Ccr , F5h , Cad and Pox ) increased in the lrd6-6 mutant ( Fig 9A ), supporting our notion that the antimicrobial metabolites, serotonin and lignin, would accumulate in the lrd6-6 mutant.…”

“…This result suggested that biosynthesis of these phytoalexins might be highly activated in the lrd6-6 mutant. Previous reports have shown that the WRKY transcription factor OsWRKY14 is required for serotonin biosynthesis through regulating the expression of genes TS ( tryptophan synthase ) and TDC ( tryptophan decarboxylase ) [ 74 , 77 ] and that the MPK genes OsMPK3 , OsMPK6 and OsMPK4 regulate the biosynthesis of lignin and phytoalexins [ 75 , 78 ]. When determining the expression of these genes, with the exception of OsMPK6 , we found that the expression of all these genes was highly increased in the lrd6-6 mutant compared with Kitaake (Figs 9B and 10B ), further supporting our notion that antimicrobial metabolites accumulated in the lrd6-6 mutant.…”

OsACL‐A2 negatively regulates cell death and disease resistance in rice

“…Serotonin content was detected as published method (Jin et al ., ). 200 mg leaf tissue at the heading stage was ground with liquid nitrogen into a powder and soaked in 1 mL 100% methanol.…”

“…Potential pathways for OsACL-A2-mediated innate immunity in rice Catalysed by OsSL (Fujiwara et al, 2010), serotonin has been reported to play a critical role in disease resistance (Hayashi et al, 2016;Jin et al, 2015). It served as a substrate for peroxidase in the presence of hydrogen peroxide to form a complex mixture of oligomerics that function as a physical barrier against the spread of pathogen infections in infected rice leaves (Ishihara et al, 2011).…”

Fine mapping and candidate gene analysis of a lesion mimic mutant <italic>spl-3t </italic>in rice

“…活性氧(reactive oxygen species, ROS)在水稻类病变发生的过程中也起 着很重要的作用 [21] , H 2 O 2 以及O 2 可能导致氧迸发, 进 而导致水稻细胞程序性死亡, 产生类病变. SPL5编码 剪接因子3b的亚基3(SF3b3), 它可能通过RNAs前体剪 接作用控制细胞死亡及防御反应 [22] . 此外, OsLSD1基 因的表达是光诱导或暗抑制, 同时OsLSD1在调节植物 PCD方面起负调控的作用, 所以在光照下会促进 OsLSD1产生病斑 [23] .…”