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Arabidopsis ALA1 and ALA2 Mediate RNAi-Based Antiviral Immunity

View Article: PubMed Central - PubMed

ABSTRACT

RNA intereferencing (RNAi) pathway regulates antiviral immunity and mediates plant growth and development. Despite considerable research efforts, a few components in RNAi pathway have been revealed, including ARGONAUTEs (AGOs), DICER-LIKEs (DCLs), RNA-dependent RNA polymerase 1 and 6 (RDR1/6), and ALTERED MERISTEM PROGRAM 1 (AMP1). In this study, we performed a forward genetic screening for enhancers of rdr6 via inoculation of CMV2aTΔ2b, a 2b-deficient Cucumber Mosaic Virus that is unable to suppress RNAi-mediated antiviral immunity. We uncover that the membrane-localized flippase Aminophospholipid ATPase 1 (ALA1) cooperates with RDR6 and RDR1 to promote antiviral immunity and regulate fertility in Arabidopsis. Moreover, we find that ALA2, a homolog of ALA1, also participates in antiviral immunity. Our findings suggest that ALA1 and ALA2 act as novel components in the RNAi pathway and function additively with RDR1 and RDR6 to mediate RNAi-based antiviral immunity and plant development.

No MeSH data available.


Related in: MedlinePlus

ALA1 acts through both RDR1/6-related and -unrelated pathways to mediate antiviral immunity. (A) Phenotypes of rdr1 rdr6, ala1-2 rdr6, ala1-2 rdr1 and ala1-2 rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. (B) Phenotypes of Col-0, rdr1 rdr6, ala1-2 rdr6 and ala1-2 rdr1 rdr6 at 45 days after infection with mock or CMV2aTΔ2b. (C) Immunoblotting analysis to detect the accumulations of CMV2aTΔ2b from leaves of Col-0, rdr6, rdr1, ala1-2, ala1-2 rdr6, ala1-2 rdr1, ala1-2 rdr1 rdr6 and rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. The coat protein (CP) of CMV2aTΔ2b was detected by anti-CP (α-CP) antibody. The large subunit of ribulose-1,5-bisphosphate was used as the loading control.
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Figure 2: ALA1 acts through both RDR1/6-related and -unrelated pathways to mediate antiviral immunity. (A) Phenotypes of rdr1 rdr6, ala1-2 rdr6, ala1-2 rdr1 and ala1-2 rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. (B) Phenotypes of Col-0, rdr1 rdr6, ala1-2 rdr6 and ala1-2 rdr1 rdr6 at 45 days after infection with mock or CMV2aTΔ2b. (C) Immunoblotting analysis to detect the accumulations of CMV2aTΔ2b from leaves of Col-0, rdr6, rdr1, ala1-2, ala1-2 rdr6, ala1-2 rdr1, ala1-2 rdr1 rdr6 and rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. The coat protein (CP) of CMV2aTΔ2b was detected by anti-CP (α-CP) antibody. The large subunit of ribulose-1,5-bisphosphate was used as the loading control.

Mentions: Further analyses of various double mutants and the triple mutant ala1-2 rdr1 rdr6 showed that all the double mutants including ala1-2 rdr6, ala1-2 rdr1, enor1 rdr6, ala1-crispr rdr6 and rdr1 rdr6 exhibited similar symptoms after inoculation with CMV2aTΔ2b, which were much more severe than the single mutant ala1-2, while the triple mutant ala1-2 rdr1 rdr6 showed the most severe symptoms with over-stunted newly born leaves and yellow old chlorotic leaves (Figures 1B,C, 2A,B and Supplementary Figure 3). These results suggest that ALA1 functions additively with RDR1 and RDR6 to mediate plant immunity.


Arabidopsis ALA1 and ALA2 Mediate RNAi-Based Antiviral Immunity
ALA1 acts through both RDR1/6-related and -unrelated pathways to mediate antiviral immunity. (A) Phenotypes of rdr1 rdr6, ala1-2 rdr6, ala1-2 rdr1 and ala1-2 rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. (B) Phenotypes of Col-0, rdr1 rdr6, ala1-2 rdr6 and ala1-2 rdr1 rdr6 at 45 days after infection with mock or CMV2aTΔ2b. (C) Immunoblotting analysis to detect the accumulations of CMV2aTΔ2b from leaves of Col-0, rdr6, rdr1, ala1-2, ala1-2 rdr6, ala1-2 rdr1, ala1-2 rdr1 rdr6 and rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. The coat protein (CP) of CMV2aTΔ2b was detected by anti-CP (α-CP) antibody. The large subunit of ribulose-1,5-bisphosphate was used as the loading control.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5383662&req=5

Figure 2: ALA1 acts through both RDR1/6-related and -unrelated pathways to mediate antiviral immunity. (A) Phenotypes of rdr1 rdr6, ala1-2 rdr6, ala1-2 rdr1 and ala1-2 rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. (B) Phenotypes of Col-0, rdr1 rdr6, ala1-2 rdr6 and ala1-2 rdr1 rdr6 at 45 days after infection with mock or CMV2aTΔ2b. (C) Immunoblotting analysis to detect the accumulations of CMV2aTΔ2b from leaves of Col-0, rdr6, rdr1, ala1-2, ala1-2 rdr6, ala1-2 rdr1, ala1-2 rdr1 rdr6 and rdr1 rdr6 at 21 days after infection with mock or CMV2aTΔ2b. The coat protein (CP) of CMV2aTΔ2b was detected by anti-CP (α-CP) antibody. The large subunit of ribulose-1,5-bisphosphate was used as the loading control.
Mentions: Further analyses of various double mutants and the triple mutant ala1-2 rdr1 rdr6 showed that all the double mutants including ala1-2 rdr6, ala1-2 rdr1, enor1 rdr6, ala1-crispr rdr6 and rdr1 rdr6 exhibited similar symptoms after inoculation with CMV2aTΔ2b, which were much more severe than the single mutant ala1-2, while the triple mutant ala1-2 rdr1 rdr6 showed the most severe symptoms with over-stunted newly born leaves and yellow old chlorotic leaves (Figures 1B,C, 2A,B and Supplementary Figure 3). These results suggest that ALA1 functions additively with RDR1 and RDR6 to mediate plant immunity.

View Article: PubMed Central - PubMed

ABSTRACT

RNA intereferencing (RNAi) pathway regulates antiviral immunity and mediates plant growth and development. Despite considerable research efforts, a few components in RNAi pathway have been revealed, including ARGONAUTEs (AGOs), DICER-LIKEs (DCLs), RNA-dependent RNA polymerase 1 and 6 (RDR1/6), and ALTERED MERISTEM PROGRAM 1 (AMP1). In this study, we performed a forward genetic screening for enhancers of rdr6 via inoculation of CMV2aTΔ2b, a 2b-deficient Cucumber Mosaic Virus that is unable to suppress RNAi-mediated antiviral immunity. We uncover that the membrane-localized flippase Aminophospholipid ATPase 1 (ALA1) cooperates with RDR6 and RDR1 to promote antiviral immunity and regulate fertility in Arabidopsis. Moreover, we find that ALA2, a homolog of ALA1, also participates in antiviral immunity. Our findings suggest that ALA1 and ALA2 act as novel components in the RNAi pathway and function additively with RDR1 and RDR6 to mediate RNAi-based antiviral immunity and plant development.

No MeSH data available.


Related in: MedlinePlus