Identification And Expressive Analysis On HD-zip Transcription Factor Gene Family From Morus

Mulberry(Morus)is a kind of important cash crops originally cropped in north and central China from the ancient times.It is cultivated throughout the country,with the largest planting area in Jiangsu,Zhejiang,Sichuan,Guangdong and Guangxi.Sericultural industry is a traditional industry in China.Since the old times,it has played an important role in accelerating the economic development of the sericultural areas and increasing the income of farmers.Guangdong Province,one of the important silkworm production areas,is located in southern China.Due to humid climate,frequent natural disasters and other reasons,the bacterial wilt is raging,the growing environment of mulberry is deteriorating,and the output of sericultural products is decreasing as well.HD-zip(Homeobox-Leucine Zipper Protein)is a unique type of transcription factors in higher plants.It possesses the function of activating or inhibiting genetic transcription and is closely related to the growth and development of plants.In recent years,it has been found that HD-zip can respond to abiotic stresses,but there is little evidence that HD-zip participating in plant disease resistance.Therefore,study the function of HD-zip gene family in disease resistance and stress resistance of mulberry to provide gene reserves for mulberry genetic breeding,which is of great importance for the sustainable development of sericultural industry.In this research,members of the HD-zip gene family of mulberry were identified and characterized.The gene sequences of 33 members were determined,and the genetic structural analysis and phylogenetic analysis were combined to finally divide the 33 members of mulberry HD-zip into four genetic subfamilies.Among them,14 genes were involved in HD-zip subfamily I,8 genes were divided into HD-zip subfamily II,HD-zip subfamily III possessed 3 members,and 8 genes shared HD-zip subfamily IV.In this paper,high-concentration Ralstonia solanacearum was used to infect the mulberry seedlings with bacterial wilt disease.A total of 6 sampling time points of 1h,3h,6h,12 h,24h and 48 h were set respectively to observe the phenotypic changes of mulberry leaves and mulberry roots after Ralstonia solanacearum infection.The results indicated that the leaves showed slight wilting symptoms after 1 hour of infection.With the increase of infection time,the symptoms of leaf wilting gradually increased.Until 24 hours after infection,they were completely dehydrated.At the same time,this study used real-time quantitative PCR to detect the different expressions of 33 members of the mulberry HD-zip gene family in the mulberry leaf and mulberry root tissues affected by the bacterial wilt disease.The results showed that all members of the HD-zip gene of mulberry tree were expressed in the leaves and root tissues before and after infection.Most family members were significantly induced by Ralstonia solanacearum in mulberry leaves or roots,indicating that the HD-zip gene family is involved in the disease resistance process of mulberry.This paper as well analyzed the expression patterns of HD-zip gene family members in mulberry seedlings under three abiotic stresses of cold,drought and high salinity.In this research,to observe the phenotypic changes of mulberry leaves under different abiotic stress treatments,cold stress was set at 3 sampling time points of 12 h,24h and 48 h,drought stress was set at 3 sampling time points of 1h,3h and 6h,and high salinity stress was set at 3 sampling time points of 3h,6h and 12 h.At the same time,real-time fluorescence quantitative PCR was used to detect the different expressions of 33 members of the mulberry HD-zip gene family in mulberry leaf tissues treated by abiotic stress.The experimental results showed that the leaves of mulberry seedlings began to wilt after 48 hours of cold stress treatment,and most of the HD-zip family genes were significantly expressed after 24 hours of cold treatment.The wilting symptoms appeared on the leaves of mulberry seedlings after 1 hour of drought stress treatment.As the treatment time increased,the symptoms of wilting increased.Most of the HD-zip family genes were significantly expressed after 3h or 6h of drought stress treatment.The leaves of mulberry seedlings showed wilting symptoms after 3 hours of treatment with high salinity stress.With the increase of treatment time,the symptoms of wilting increased.Most of the HD-zip family genes were significantly expressed after 3h or 6h of high salinity stress treatment.In summary,HD-zip gene family genes play an important role in the abiotic stress of mulberry.In this study,mulberry was used as the experimental object.For the first time,the genes of the HD-zip family of mulberry were identified,classified,and analyzed,and the changes in the expression of the HD-zip family during the infection of Ralstonia solanacearum and abiotic stress were clarified.The results of the study will lay a solid foundation for an in-depth understanding of the functions and mechanisms of the mulberry HD-zip gene family involved in resistance to bacterial wilt and stress resistance.