Analyzing On The Function Of MMDH2 In Response To Iron Deficiency In Arabidopsis Thaliana

Alkaline soils account for about 30%of the total soil area in the world,but the solubility of iron in alkaline soil is extremely low,which reduces the uptake of iron by plants,thus affecting the growth and development of plants themselves and finally endangering human health through the food chain.Hence it is of significance and application value to study the response mechanism of plants to iron deficiency.In this study,the mitochondrial malate dehydrogenase(mMDH2)gene of Arabidopsis thaliana was taken as the research object to explore its function and mechanism in iron deficiency stress,and to provide new gene resources and technical approaches for crop mineral nutrition molecular breeding.The main research results are as follows:1?In order to investigate whether mMDH2 gene was induced by iron deficiency stress,GUS staining analysis was performed on PromMDH2-GUS transgenic plants.It was found that the staining of transgenic seedlings was significantly deeper than that of the control under iron deficiency stress.The results of q RT-PCR also showed that mMDH2 gene was induced under iron deficiency stress.2?Compared with wild type(WT),the loss of function mutants mmdh2-1 and mmdh2-2 of Arabidopsis were more sensitive to iron deficiency stress,while35S:mMDH2-overexpressed plants were more tolerant to iron deficiency stress.It is suggested that mMDH2 was involved in the regulation of Arabidopsis response to iron deficiency stress.3?DAB staining and determination of hydrogen peroxide content showed that under iron deficiency stress,DAB staining of mmdh2 mutant was significantly deeper than that of WT,and its H₂O₂ content was higher than WT,while the H₂O₂ content in35S:mMDH2-overexpressed plants was lower than WT.It is speculated that mMDH2gene may participate in the regulation of iron deficiency stress through H₂O₂.4?The expression of genes related to iron deficiency stress in WT and mmdh2mutants was analyzed by q RT-PCR assay.It was found that there was no significant difference in the transcription levels of IRT1,FRO2 and NAS2 genes,while the transcription level of NAS4 gene in mmdh2 mutants was significantly lower than that in WT under iron deficiency stress.These results suggested that mMDH2 may regulate the response of Arabidopsis to iron deficiency stress by regulating the expression of NAS4gene.5?The iron content of WT,mmdh2 mutant and 35S:mMDH2-overexpressed plants under iron deficiency stress were analyzed.It was found that the iron content in the roots and stems of the mmdh2 mutant was lower than that of WT,but the ratio of root-stem of mmdh2 mutant was higher than WT.The iron content in roots and stems of 35S:mMDH2overexpressed plants was higher than that of WT,but the ratio of root-stem of it's was lower than that of WT.These results indicated that mMDH2 may regulate iron content in Arabidopsis thaliana by regulating the expression of iron transport-related genes and respond to iron deficiency stress.6?We measured the effect of mMDH2 gene loss on tricarboxylic acid cycle in plants under iron deficiency stress:Compared with WT,the contents of OAA and NADH in mmdh2 mutants decreased significantly under iron deficiency stress,while the contents in 35S:mMDH2 overexpressed plants increased.It is speculated that the iron-deficiency sensitive phenotype of mmdh2 mutant may be related to OAA.7?The iron-deficiency sensitive phenotype of mmdh2 mutant was restored on the iron-deficiency medium supplemented with 200?M OAA and Asp respectively,and OAA and Asp were precursors of NA.It is assumed that the response of mMDH2 gene to iron-deficiency regulation may be partly realized by influencing the synthesis of NA.In summary,the mMDH2 gene can positively regulate the response to iron deficiency stress,and its mechanism may be to improve the tolerance of Arabidopsis thaliana to iron deficiency stress by regulating the expression of NAS4 gene and affecting the synthesis of NA.