In plants, sphingolipids, such as long-chain bases (LCBs), act as bioactive molecules in stress responses. Until now, it is still not clear if these lipids are involved in biotic stress responses to herbivore. Herein we report that a rice LCB gene, OsLCB2a1 encoding a subunit of serine palmitoyltransferase (SPT), a key enzyme responsible for the de novo biosynthesis of sphingolipids, plays a critical role in plant defense response to the brown planthopper (BPH) attack and that its up-regulation protects plants from herbivore infestation. Transcripts of OsLCB2a1 gene in rice seedlings were increased at 4 h, but decreased at 8–24 h after BPH attack. Sphingolipid measurement profiling revealed that overexpression of OsLCB2a1 in Arabidopsis thaliana increased trihydroxylated LCB phytosphingosine (t18:0) and phytoceramide by 1.7 and 1.3-fold, respectively, compared with that of wild type (WT) plants. Transgenic Arabidopsis plants also showed higher callose and wax deposition in leaves than that of WT. Overexpression of OsLCB2a1 gene in A. thaliana reduced the population size of green peach aphid (Myzus persicae). Moreover, the electrical penetration graph (EPG) results indicated that the aphids encounter resistance factors while reaching for the phloem on the transgenic plants. The defense response genes related to salicylic acid signaling pathway, remained uplgulated in the OsLCB2a1-overexpressing transgenic plants. Our data highlight the key functions of OsLCB2a1 in biotic stress response in plants.

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The abundance, incidence pattern and species composition of green leafhopper (GLH) in seedbed, rice field and light trap were studied in three rice growing seasons in Bangladesh during 2004 and 2005. Five species of GLH were recorded. These were Nephotettix virescens, N. nigropictus, N. malayanus, N. parvus and N. cincticeps. The first two species were most important as their presence were higher in number almost all the year round. More GLH was observed in 2005 compared to 2004 in all habitats. The GLH population was higher in seedbed than transplanted rice. Seedbed of both the year prevailed highest number of GLH than transplanted rice. Among 5 species of GLH N. nigropictus was found higher in summer and winter rice seedbed during 2005. Nephotettix virescenswas dominant in summer rice seed bed in both the year and transplanted monsoon rice field in the year 2005. The number of other 3 species of GLH was comparatively low in all the season and habitats. Temperature and rainfall influenced the population of GLH. The fluctuation of GLH population in the rice field did not always represent the fluctuation of light trap catches. The abundance of 5 GLH species in the order of N. virescens> N. nigropictus> N. malayanus> N. cincticeps > N. parvus.