Abstract:To reveal the role of IAA and its signaling genes in the retrieved green process of pear leaves, chlorotic and normal plants of ‘Dangshansuli’ (Pyrus bretschneideri Rehd.) were taken as test material. What’s more, 0.20% FeSO4 solution were sprayed on the chlorotic leaves and distilled water were used for both normal and chlorotic leaves as control during the growing season, . then Then observing the leaves phenotypic changes on 3rd, 6th, 9th, and 12th d after FeSO4 application, respectively..Ssampling normal, chlorotic leaves in control (CN and CC)andthe leaves of retrieved green leaves (RL) on 3rd, 6th, 9th, 12th d after the 0.20% FeSO4 application and storing them in ?80℃ refrigerators, to determine . Tthe Fe2+ content, endogenous IAA content and of samples were determined by ELISA and the expression of IAA signaling genes expression related to IAA signal transduction were analyzed by qRT-PCR with reference to the NCBI and pear genome. Furthermore, relevance analysis was performed by SPSS among those indexes. The results were shown as followingfollows: (1) Application FeSO4 could convert chlorotic leaves to green, Green green spots appeared on the chlorotic leaf leaves surface on 3rd d, and green plaque appeared on both 6th and 9th d after spraying FeSO4. What’s more, the whole leaf presented green on 12th d. (2) The endogenous IAA content in CNnormal leaves of control (NL) was significantly higher than that in CCchlorotic leaves (CL), and after the sprayingapplication of FeSO4, it obviously increased in RL retrieved green leaves compared to with both CN and CC CL in all periods, which were significantly higher than NL. (3) The expression of AUX1.1/1.3、GH3.1/3.2/3.5、SAUR1/2/3/4 and AUX/IAA1/2/3/7TIR1.1, GH3.1/3.2/3.5, AUX1.2/1.3, AUX/IAA1/3/7 and SAUR1/2/3/4 expression in CC CL were prominently higher than that in CN NL, and FeSO4 applicationmost of them were notably inhibited their expression in an outstanding levelin all period after spraying FeSO4. In contrastMeanwhile, TIR1.1、GH3.3/3.4 and AUX/IAA4/5/6 and GH3.3/3.4 expression in CcCL were distinctively lower than that in CNNL, and they were all apparently promoted by FeSO4 application. (4) ARF3/4/5/6/7/8/9/ 10/15/17/18/19/20/21/22/23 in Cc were clearly decreased compared with CN, and FeSO4 application significantly promoted the expression of ARF3/5/6/9/19/20/21/22/23; On the contrary, ARF1/2/11/12/13/14 were remarkably increased in CcCL compared to CNNL, and FeSO4 application remarkably suppressed the expression of ARF1/2. (5) The relevance analysis showed that remarkably increased Fe2+ content in retrieved green leaves was positively correlated with to the up-regulation of AUX/IAA5 and AUX/IAA6 expression, while IAA content was positively correlated with the increased GH3.3 expression and negatively correlated with the decreased SAUR1/2 expression. The network diagram of the association between the two above is complex, which can be simplified into Fe2+→ AUX/IAA5, AUX/IAA6→(ARF14)→ ARF5 SAUR1, AUX/IAA1→ SAUR2, TIR1.1, GH3.3→ IAA. The study suggested that IAA and its signaling pathway might play a crucial role in the retrieved green process induced by spraying FeSO4 inon iron-deficiency chlorotic leaves of ‘Dangshansuli’.