Response Differences Between Females And Males Of Populus Deltoides To Pestalotiopsis Microspora Infection

Dioecy play important roles in maintaining biodiversity and ecosystem stability.Because they have differences in heredity and sensibility to environmental stresses,emerging sexual dimorphism of growth,reproduction,spatial distribution and resource allocation.Populus is a typical dioecy,which has large biomass,fast growth and good material.But poplar often suffer many pathogens infection to get sick during growth.Pestalotiopsis microspore is a representative pathogen that poisons numerous plants.Poplar are usual hosts of Pestalotiopsis microspore.In recent years,researches on sexual dimorphism of dioecy mainly focus on their physiological and molecular variation to abiotic stress,but it is scarce in biotic stress at molecular level.In this paper,using Populus deltoides as a object,after inoculating with Pestalotiopsis microspore,we studied the sexual responsive differences to disease in leaf infection degrees,subcellular structure,hormones,hypersensitivity response（HR）and transcriptome,in order to understand sexual differences of Populus deltoides response to Pestalotiopsis microspore infection at molecular level,and provide theories of application,breeding and improving for Populus deltoides in areas with disease of Pestalotiopsis microspore.The primary consequences are follows:（1）After infected and developed diseases,the infection degrees of males wereⅡ,and females wereⅢwhich were higher than males.This indicated the poison degrees of males were lower than femles,and males possessed stronger resistance.（2）Using transmission electron microscope,we found that lamellar structure of granums of mesophyll cells were rearrangement,loose and disorder in both sexes of infection poplar leaves.There were fake granums in females.The results manifested the subcellular structure suffer damage in both sexes,but the impaired degrees of females were higher than males.（3）Compared with control,gibberellin（GA）contents were significantly decreased by32.80%in males,but other hormones contents were not important variation in both sexes.（4）Males’hydrogen peroxide（H₂O₂）contents were importantly increased by 54.47%.Experiments indicated that H₂O₂ dying,HR dying and cell death degrees of males were higher than females by diaminobenzidine（DAB）,trypan blue and terminal deoxynucleotidyl transferasemediated d UT nick end labeling（Tunel）.These data implied that males can enrich more H₂O₂ and produce abundant HR to suppress pathogens invading other healthy cells.（5）Utilizing transcriptome sequencing,compared with control,we identified 1,663and 1,616 DEGs in females and males,respectively.These results demonstrated photosynthesis and heat shock protein（HSP）pathways were suppression in both sexes at different levels.But hormones,HR,antioxidant system（glutathione S-transferase and peroxidase）,resistance gene（R gene）,secondary metabolism and GDSL lipase played important roles in poplar response to Pestalotiopsis microspore infection at different levels.Therefore,these different response patterns between females and males made for reduced harms in subcellular structure and photosynthetic apparatus,lower leaves infection levels and more robust disease resistance of males were higher than females infected by Pestalotiopsis microspore.