OsABCG9 Is an Important ABC Transporter of Cuticular Wax Deposition in Rice

Abstract

The importance of the cuticular layer in regulating a plant’s water status and providing protection from environmental challenges has been recognized for a long time. The cuticular layer in plants restricts non-stomatal water loss and protects plants against damage from pathogen infection and UV radiation. Much genetic and biochemical research has been done about cutin and wax transportation in Arabidopsis thaliana, but little is known about it in rice. Here, we report that a rice ATP-binding cassette (ABC) transporter, OsABCG9, is essential for normal development during vegetative growth and could play a critical role in the transportation of epicuticular wax in rice. Rice phenotypes with mutated OsABCG9 exhibited growth retardation and sensitivity to low humidity. The total amount of cuticular wax on the leaves of the osabcg9-1 mutant diminished by 53% compared with the wild type, and wax crystals disappeared completely in osabcg9-2 mutant leaves. However, OsABCG9 does not seem to be involved in cutin transportation, even though its ortholog in Arabidopsis, AtABCG11, transports both wax and cutin. Furthermore, the osabcg9-1 mutant had increased leaf chlorophyll leaching and more severe drought susceptibility. This study provides new insights about differences between rice and A. thaliana in wax and cutin transportation associated with the ABCG family during evolution.

Transcriptome and Physiological Analyses of a Navel Orange Mutant with Improved Drought Tolerance and Water Use Efficiency Caused by Increases of Cuticular Wax Accumulation and ROS Scavenging Capacity

“…Thus, the significant increase in the expression level of CsCER3-LIKE may explain the sharp increase in n-alkane amounts in MT leaves ( Table 1 and Figure 10 A). To date, numerous ABC transporter G subfamily genes, such as AtABCG11 and AtABCG12 from Arabidopsis, OsABCG9 from rice, PpABCG7 from Physcomitrella patens and glossy13 ( AtABCG32 homolog) from maize, have been reported to export the cuticular waxes from plasma membrane (PM) to an apoplastic environment [ 55 , 56 , 57 , 58 , 59 ]. In this study, the expression levels of two ABC transporter G subfamily DEGs ( CsABCG11-LIKE and CsABCG21-LIKE ) in MT leaves were much higher than those in WT leaves under control and drought stress ( Table 1 and Figure 10 G,H).…”

Ecophysiology with barley eceriferum (cer) mutants: the effects of humidity and wax crystal structure on yield and vegetative parameters

“…The surprising diversity in phenotypes that are affected by a single cer mutation is hardly surprising given that the wax components not only have to be synthesized but also have to be transported to the surface, with both processes requiring high levels of regulation and coordination. For example, expression studies of OsABCG9 imply that its product transports not only epidermal wax aliphatics but also other lipid-like molecules in different types of cells ( Nguyen et al , 2018 ).…”

Full-length transcriptional analysis reveals the complex relationship of leaves and roots in responses to cold-drought combined stress in common vetch

“…Previous studies have found that the OsABCG9 gene is primarily expressed in rice leaves during vegetative growth. In mutated OsABCG9 plants, the cuticular wax contents on the leaves are diminished by half, and this mutant exhibited growth retardation and sensitivity to drought stress (Nguyen et al, 2018). It is worth noting that the pathway of "Cutin, suberin, and wax biosynthesis" was significantly enriched in leaves.…”