Pha13 A20 and AN1 domains are involved in the expression of PhaNPR1-dependent and -independent immune gene(s) and virus accumulation.

<p>(A and B) Expression level of <i>Pha13</i>, <i>PhaNPR1</i>, <i>PhaRdR1</i>, <i>PhaGRX</i>, and CymMV accumulation level were analyzed by qRT-PCR of healthy <i>P</i>. <i>aphrodite</i> leaves (A), or CymMV pre-infected <i>P</i>. <i>aphrodite</i> (B) and infiltrated with agrobacterium carrying vector (Vector), overexpression clones of Pha13, or the respective A20 and/or AN1 mutant clones. The RNA level of vector was set to 1. Data represent mean ± SD; n = 3 biological replicates; *, <i>P</i> < 0.05, Student’s t-test compared to vector. <i>PhaUbiquitin 10</i> was used as an internal control for normalization. (C) A model illustrating SA-induced <i>Pha13</i> transcriptional and post-translational regulation leading to the activation of immune responsive genes. Virus infection caused accumulation of SA and leads to post-translational modification of NPR1, allowing it to enter into the nucleus for the activation of NPR1-dependent immune responsive genes including <i>PR1</i> and <i>RdR1</i>. On the other hand, increased SA can also regulate <i>Pha13</i> at both transcriptional and post-translational level and leads to the expression of NPR1-dependent and independent immune responsive genes including <i>NPR1</i>, <i>RdR1</i> and <i>GRX</i> for virus resistance.</p>