Bph32, a novel gene encoding an unknown SCR domain-containing protein, confers resistance against the brown planthopper in rice

Abstract

An urgent need exists to identify more brown planthopper (Nilaparvata lugens Stål, BPH) resistance genes, which will allow the development of rice varieties with resistance to BPH to counteract the increased incidence of this pest species. Here, using bioinformatics and DNA sequencing approaches, we identified a novel BPH resistance gene, LOC_Os06g03240 (MSU LOCUS ID), from the rice variety Ptb33 in the interval between the markers RM19291 and RM8072 on the short arm of chromosome 6, where a gene for resistance to BPH was mapped by Jirapong Jairin et al. and renamed as “Bph32”. This gene encodes a unique short consensus repeat (SCR) domain protein. Sequence comparison revealed that the Bph32 gene shares 100% sequence identity with its allele in Oryza latifolia. The transgenic introgression of Bph32 into a susceptible rice variety significantly improved resistance to BPH. Expression analysis revealed that Bph32 was highly expressed in the leaf sheaths, where BPH primarily settles and feeds, at 2 and 24 h after BPH infestation, suggesting that Bph32 may inhibit feeding in BPH. Western blotting revealed the presence of Pph (Ptb33) and Tph (TN1) proteins using a Penta-His antibody, and both proteins were insoluble. This study provides information regarding a valuable gene for rice defence against insect pests.

Loss of Resistance to <i>Nilaparvata lugens</i> May Be Due to the Low-Level Expression of <i>BPH32 </i>in Rice Panicles at the Heading Stage

“…Real-time PCR analysis showed that BPH32 was expressed in all investigated tissues at the flowering stage, and its expression level was the highest in leaf sheaths followed by leaf blades, culms, and roots but not the panicle [9]. The result of our study was consistent with previous studies that showed high BPH32 expression in the leaf sheaths but a poor expression in the uppermost internode at heading stage of the same plant.…”

“…BPH32 which encloses a unique short consensus repeat domain protein and is located in the plasma membrane, has been reported to inhibit BPH feeding [9].…”

“…The constitutively expressed actin gene was amplified as an internal control from rice leaf sheaths and panicles. The specific primers used in RT-PCR for BPH32 and actin genes [9] were as follows: 5'-TGGGTTCCGGTGGACCTGGG-3' (BPH32 forward), …”

“…The BPH32 encodes a short consensus repeat domain-containing protein that confers an antibiosis resistance to BPH and is localized in the plasma membrane. This gene is highly expressed in the leaf sheaths but poorly expressed in the panicles of rice plants [9]. Jairin et al [11] reported that the resistant cultivars RH and PTB33 were highly resistant to BPH at the vegetative stage (seedling to maximum tillering stages) of heavy BPH infestation, but showed susceptibility at the reproductive stage.…”

“…The BPH resistance locus has been widely used in BPH resistance breeding via marker-assisted selection (MAS) [5] [6] [7] [8]. Recently, the BPH3 gene was identified and renamed as BPH32 [9] to avoid confusion with the cloned BPH3 cluster genes located on the short arm of chromosome 4 [10]. The BPH32 encodes a short consensus repeat domain-containing protein that confers an antibiosis resistance to BPH and is localized in the plasma membrane.…”