ABA alleviates nitrate-mediated Fe deficiency response
Previous studies have shown that nitrogen deficiency resulted in the accumulation of ABA (Krauss et al, 1978; Teplova et al, 1998) and our RNA-seq analysis also demonstrated that nitrate treatment affected the expression of genes related to ABA metabolism and signaling (Fig. S6). Considering ABA plays a role in alleviating Fe deficiency response (Lei et al. 2014), it seems likely that it is also involved in nitrate-regulated iron deficiency responses. To assess this possibility, endogenous ABA content was measured in seedlings of ‘Pinyiensis ’ under different nitrate treatments. ABA content increased with LN treatment in roots (Fig. 7b), while there was no apparent difference in ABA content in leaves (Fig. 7a). Meanwhile, exogenous ABA application partially rescued the chlorosis phenotype in response to HN treatment (Fig. 7c, d). These results indicated that LN promoted ABA accumulation in roots quickly, and that LN alleviated iron deficiency partially through promoting ABA accumulation in roots.