Development Of Maize Root Systems And Its Response To Exogenous Auxin Under Zinc-deficient Stress

In this study,we have selected Zhengdan 958 maize as experimental material to culture in nutrient solution,and carried out the following research: zinc deficiency stress and effects on root morphology of Maize by supplying exogenous Indole acetic acid,zinc deficiency stress and effects on root morphology of maize by supplying exogenous Naphthalene acetic acid,effects of Zinc Deficiency Stress on content of IAA in different regions of Maize roots and comparison of ZmAUX1 and ZmPINl gene expression in the elongated process of primary roots and lateral root under zinc deficiency.Finally,several conclusions have been got in the following.1.The growth of maize was inhibited under zinc deficiency stress,the dry weight of above-ground maize parts decreased,the content of zinc in the aerial part of maize is less than 10 mg / kg and lower than the necessary content of zinc.In this case,maize seemed dwarfed because of internodes being severely hampered,mesophyll tissue paralleling to leaf veins became thinning,green faded stripes or Albino appeared in the both sides of the blade midvein.Appropriate zinc supplying could make a significant improvement in maize growth,and the biomass of above-ground parts would be significantly improved.2.In the case of zinc deficiency,the development of maize roots was inhibited,especially the whole root characteristic.The total root length,total root surface area,total root volume,total lateral length and average lateral length significantly decreased,while the density of lateral roots was significantly improved.Under zinc deficiency,the root length obviously increased when root diameter was between 0.45 mm and 1.05 mm or more than 1.05 mm,but there was no significant difference when root diameter was less than 0.45 mm.The lateral root density being significant increase is beneficial to enhance the ability of roots to absorb zinc from the soil.3.Under zinc deficiency,supplying exogenous Indole acetic acid(IAA)did not make any difference in the characteristics of primary roots,the characteristics of seeds and the characteristics of whole roots.But supplying low concentration of exogenous Indole acetic acid(IAA)could significantly reduce total root length,total root surface area and total root volume when zinc was enough.4.Under zinc deficiency,supplying exogenous Naphthalene acetic acid(NAA)did not make any difference in the characteristics of primary roots and the characteristics of seeds,but reduce total root length,total root surface area and total root volume.When zinc was enough,supplying low concentration of exogenous NAA did not make any difference.But supplying high concentration of exogenous NAA could significantly increase the total root length,total root surface area and total root volume.5.Supplying exogenous auxin inhibitors could inhibite development of maize roots,especially the whole root characteristic.But there was no difference when the auxin was IAA and zinc was enough.6.The content of auxin in different regions of root was determined by GC-MS.The results showed that the content of auxin in the root tissue of 0-1cm and 1-2cm was lower than that in the control group under zinc deficiency,and the difference was significant.Under zinc deficiency,the content of auxin in 0-1cm and 1-2cm root tissue was nearly the same.But the content of auxin was lower near the apical part of roots,while higher far away and the difference is obvious.7.The expression of key gene of auxin Metabolism Transportation in maize roots was determined by RT-qPCR.The results showed that zinc deficiency could inhibit the expression of AUX1 and PIN1 c in maize(P <0.05).In this study,the expression of ZmAUX1 and ZmPIN1 c in the root was less weak than that of supplying enough zine,which could obstruct the polar transport of auxin in the root,disorder the distribution of auxin and affect root growth and development.