An ABC transporter, OsABCG26, is required for anther cuticle and pollen exine formation and pollen-pistil interactions in rice

Abstract

Wax, cutin and sporopollenin are essential components for the formation of the anther cuticle and the pollen exine, respectively. Their lipid precursors are synthesized by secretory tapetal cells and transported to the anther and microspore surface for deposition. However, the molecular mechanisms involved in the formation of the anther cuticle and pollen exine are poorly understood in rice. Here, we characterized a rice male sterile mutant osabcg26. Molecular cloning and sequence analysis revealed a point mutation in the gene encoding an ATP binding cassette transporter G26 (OsABCG26). OsABCG26 was specifically expressed in the anther and pistil. Cytological analysis revealed defects in tapetal cells, lipidic Ubisch bodies, pollen exine, and anther cuticle in the osabcg26 mutant. Expression of some key genes involved in lipid metabolism and transport, such as UDT1, WDA1, CYP704B2, OsABCG15, OsC4 and OsC6, was significantly altered in osabcg26 anther, possibly due to a disturbance in the homeostasis of anther lipid metabolism and transport. Additionally, wild-type pollen tubes showed a growth defect in osabcg26 pistils, leading to low seed setting in osabcg26 cross-pollinated with the wild-type pollen. These results indicated that OsABCG26 plays an important role in anther cuticle and pollen exine formation and pollen-pistil interactions in rice.

Maize Genic Male-Sterility Genes and Their Applications in Hybrid Breeding: Progress and Perspectives

“…The eight cluster I genes are expressed highly at anther stage 5 and are maize orthologs of EMS1/EXS (Zhao et al, 2002), TGA9/10 (Murmu et al, 2010), and AtSK32 (Dong et al, 2015) in Arabidopsis, and MSP1 (Nonomura et al, 2003) and OsFTIP7 (Song et al, 2018) in rice. The 17 cluster II genes are expressed highly at stage 6 (subcluster II-1) or stages 6-7 (subcluster II-2), and are maize orthologs of LBD10 (Kim et al, 2015), ARF17 (Yang et al, 2013), RPG1 (Guan et al, 2008), CalS5 (Dong et al, 2005), CDM1 (Lu et al, 2014), RBOHE (Xie et al, 2014), and EMS1/EXS in Arabidopsis, OsABCG26 (Chang et al, 2016b), DTC1 (Yi et al, 2016), MTR1 (Tan et al, 2012), OsUAM3 (Sumiyoshi et al, 2015), and OsDPW2 (Xu et al, 2017) in rice, and TaMs1 (Wang et al, 2017) in wheat. The 16 cluster III genes are expressed highly during stages 6-9 (subcluster III-1) or at stage 9 (subcluster III-2), and are maize orthologs of MMD1 (Yang et al, 2003), ACOS5 (de Azevedo Souza et al, 2009), LBD10 (Kim et al, 2015), FLP1/WAX2 (Chen et al, 2003), AMS (Xu et al, 2010), DRL1/TKPR1 (Grienenberger et al, 2010), PKSA/LAP6 and PKSB/LAP5 (Kim et al, 2010), Ms188/MYB80/AtMYB103 (Higginson et al, 2003), TEK (Lou et al, 2014), and ABCG26 (Quilichini et al, 2010) in Arabidopsis, and OsRAFTIN (Wang et al, 2003) and WDA1 (Jung et al, 2006) in rice.…”

“…The 16 cluster III genes are expressed highly during stages 6-9 (subcluster III-1) or at stage 9 (subcluster III-2), and are maize orthologs of MMD1 (Yang et al, 2003), ACOS5 (de Azevedo Souza et al, 2009), LBD10 (Kim et al, 2015), FLP1/WAX2 (Chen et al, 2003), AMS (Xu et al, 2010), DRL1/TKPR1 (Grienenberger et al, 2010), PKSA/LAP6 and PKSB/LAP5 (Kim et al, 2010), Ms188/MYB80/AtMYB103 (Higginson et al, 2003), TEK (Lou et al, 2014), and ABCG26 (Quilichini et al, 2010) in Arabidopsis, and OsRAFTIN (Wang et al, 2003) and WDA1 (Jung et al, 2006) in rice. The three cluster IV genes are expressed highly at both stages 6 and 8b/9 and are maize orthologs of OsABCG26 (Chang et al, 2016b), EAT1/DTD (Niu et al, 2013), and CAP1 (Ueda et al, 2013) in rice. The 18 cluster V genes are expressed constitutively during all the six anther stages and are maize orthologs of NPU (Chang et al, 2012), AtGPAT6 (Li et al, 2012), FLP1/WAX2, MYB33 (Millar and Gubler, 2005), RBOHE, NEF1 (Ariizumi et al, 2004), TGA9, and EMS1/EXS in Arabidopsis, and API5 (Li et al, 2011b), OsDEX1 (Yu et al, 2016), DTM1 (Yi et al, 2012), OsGT1 (Moon et al, 2013b), GAMYB (Aya et al, 2009), CSA (Zhang et al, 2010b), and OsFIGNL1 (Zhang et al, 2017) in rice.…”

TDR INTERACTING PROTEIN 3, encoding a PHD‐finger transcription factor, regulates Ubisch bodies and pollen wall formation in rice

“…All the sporopollenin precursors synthesized by enzymatic reaction are allocated for pollen wall development from tapetal cells to the anther locule. Lipid transfer protein OsC6 and ABC subfamily G (ABCG) transporters OsABCG15 and OsABCG26 may be responsible for the transport of sporopollenin precursors (Zhang et al ., ; Niu et al ., 2013a; Wu et al ., ; Zhao et al ., ; Chang et al ., ).…”

Molecular Cloning of Genic Male-Sterility Genes and Their Applications for Plant Heterosis via Biotechnology-based Male-sterility Systems

“…This modified method does not need an assembled WT genome as reference and thus is more cost-effective and widely applicable. The modified MutMap method was used for GMS gene cloning in rice and wheat, such as OsABCG26 [68], OsNP1 [69], and TaMs1 [70] ( Table 1). As the next-generation sequencing technology advances and cost of sequencing decreases rapidly, the MutMap method will be applicable for more crop plants except for rice and wheat.…”