Expression of nuclear genes of mitochondrial proteins is affected by the loss of AT5G08670
RNA-seq analysis revealed that the expression of AT5G08670 was significantly lower ingun1 , SALK_047877 , andSALK_083115 than in WT seedlings (Figure 7a). In contrast, expression of AT5G08690 was significantly higher in gun1 ,SALK_047877 , and SALK_083115 than in WT seedlings suggesting some compensatory mechanism (Figure 7b). After LIN treatment, the expression of both AT5G08670 and AT5G08690 decreased (Figure 7a-b). The expression of AT5G08670 was decreased and that of AT5G08690 was raised in the gun1 mutant compared with WT seedlings (Figure 7a-b). Similar to gun1 , the expression ofAT5G08690 was higher in the SALK lines than in WT seedlings treated with LIN. These results indicate thatGUN1 -mediated signals influence the expression of nuclear genes of mitochondrial proteins upon LIN treatment. We next analyzed the regulatory effects of AT5G08670 on some key genes involved in plastid and mitochondrial signaling. GUN1 , GUN4 , andGUN5 are important regulators of plastid signaling. After LIN treatment, the expression of GUN4 and GUN5 was decreased to different degrees in the T-DNA insertion mutants, in which the expression ofGUN1 increased relative to the control (Figure 8a). We also analyzed the expression of important regulators of nuclear genes of mitochondrial proteins such as ALTERNATIVE OXIDASE 1D(AOX1D ), AOX1A , AOX1C , and AOX2. The expression of AOX1D and AOX1A increased in WT seedlings treated with LIN, and the expression of these genes was decreased inSALK_047877 and SALK_083115 (Figure 8b). The expression of AOX2 was suppressed in all mutants treated with LIN (Figure 8b). Further, the analysis of the expression of carbon metabolism genes revealed that 1-Aminocyclopropane-1-Carboxylate Oxidase 1(ACO1 ) was decreased in all groups, except in WT seedlings following LIN treatment; the expression of ACO2 , ACO3 ,hexokinase 1 (HXK1 ), and HXK2 was decreased to different degrees in all samples (Figure 8c-d), and the expression ofmitochondrial Malate Dehydrogenase 1 (mMDH1 ) was significantly inhibited in WT seedlings (Figure 8d). The transcript levels of LIN-repressed genes, such as GUN4 , GUN5 ,AOX1C , HXK1 , HXK2 , and mMDH1 , were higher ingun1 , SALK_047877, and SALK_083115 seedlings than in WT seedlings treated with LIN. In contrast, the transcript levels of the LIN-induced genes AOX2 , AOX1D , AOX1A ,ACO1 , and ACO2 were lower in gun1 ,SALK_047877, and SALK_083115 , seedlings than in WT seedlings in the presence of LIN. These findings indicate thatGUN1 and AT5G08670 dependent signaling pathways play important roles in regulating the expression of nuclear genes of both chloroplast and mitochondrial proteins in response to LIN (Figure 10).