Effects Of Nitrogen,Iron And Zinc Deficiency On The Growth And Development Of Areca Seedlings

Areca catechu is a plant of the genus Areca of the palm family.It has high medicinal and edible value and is one of the most important economic crops in Hainan Province.However,in recent years,betel nut has been widely planted and promoted in Hainan every year.Many areas have formed a betel nut planting system with large planting density and single species,and no pre-set water and fertilizer management and soil improvement have led to the decline of soil cultivability and fertility.Insufficiency,the betel nut plant cannot obtain sufficient nutrients,so the growth of the betel nut is inhibited,the resistance is reduced,the pests and diseases are frequent,and the yellowing phenomenon is getting worse,resulting in a shorter harvest period and a decline in yield and quality [14].This has created obstacles to the healthy development of betel nut planting and processing industries.Optimize water and fertilizer management to improve soil fertility.Nitrogen,iron,and zinc are the mineral elements that are exposed to demand during the growth and development of betel nut.Their supply level has a significant impact on the normal growth of betel nut seedlings.Therefore,it has been proved that betel nut is physiologically and under nutrient deficiency conditions.The molecular response mechanism is of great significance.When the longitudinal diameter of the male flower bud of the Hevea brasiliensis Reyan 7-33-97 was between 2.81 ～ 3.20 mm,the pollen grains developed mostly in the mononuclear apposition period,which was the suitable explant for the dedifferentiation callus of the fragile and crisp anther.In this study,areca seedlings were used as research materials,and through nutrientdeficiency hydroponics,the physiological and molecular levels of areca seedlings’ response mechanisms under conditions of iron,zinc and nitrogen deficiency were systematically studied.The content includes the following five parts:(1)Iron and zinc deficiency treatments resulted in a significant decrease in the biomass of the above-ground,underground and whole plants of betel nut;under the treatment of nitrogen deficiency,the above-ground biomass of betel nut seedlings decreased while the below-ground biomass increased,resulting in a significant root-shoot ratio It is higher than the control,indicating that the betel nut seedlings under the nitrogen deficiency treatment can maintain the growth balance between the root system and the aboveground part by adjusting the biomass distribution between the aboveground part and the belowground part.(2)The determination and analysis of the chlorophyll content,photosynthetic characteristics,and microstructure of the leaves of different phyllodes of betel nut seedlings under different treatments found that the lack of nitrogen,iron and zinc significantly reduced the chlorophyll content and photosynthesis of the leaves of each phyllodes of betel nut seedlings.At the same time,it has a certain impact on the microstructure of each phyllodes leaf.Compared with the control,the content of chlorophyll a and chlorophyll b of betel nut seedlings L1,L2,and L3(three leaves in turn from the new leaf)under the treatment of nitrogen deficiency decreased significantly,and the chlorophyll a/b value increased significantly.The leaves showed different degrees of yellowing,and the chlorophyll fluorescence parameters such as Fv/Fm,Y(Ⅱ),Y(Ⅰ),q P,etc.were all significantly reduced,indicating that the photochemical reaction of PS Ⅱ and PS Ⅰ reaction centers was reduced,and the photosynthetic capacity of the leaves was reduced and lacked.Nitrogen also caused the leaf thickness of each phyllodes of betel nut seedlings to increase,while the leaf mesophyll cell density was significantly reduced;iron deficiency and zinc deficiency treatments had similar effects on the leaves of betel nut seedlings,mainly as the content of L1,L3 chlorophyll a and chlorophyll b decreased significantly,L1 chlorophyll a/b value increased while L3 chlorophyll a/b value decreased,leaf Fv/Fm,Y(Ⅱ),Y(Ⅰ),q P and other chlorophyll fluorescence parameters all decreased,and the impact on L1 was more The L1 leaves of the two betel nut seedlings showed obvious yellowing.The deficiencies of iron and zinc lead to a significant decrease in leaf thickness of each phyllodes of betel nut seedlings,and a significant increase in leaf mesophyll cell density.(3)This study determined the content of mineral elements in different leaf sequence leaves and root tissues of betel nut seedlings under nitrogen,iron,zinc and control treatments.The results showed that the lack of nitrogen not only affected the absorption and accumulation of nitrogen by betel nut seedlings At the same time,it also affects its absorption of potassium,magnesium,calcium and other large and medium elements.Nitrogen deficiency caused a significant decrease in N and Ca elements in L1,L2,L3,and R(root)of betel nut seedlings,while K and Mg content increased;iron deficiency treatment resulted in new leaves(L1)and roots of betel nut seedlings The iron content of betel nut was significantly reduced,while the zinc content increased in L1,L3 and R;zinc deficiency treatment also resulted in a significant decrease in zinc content in the new leaves(L1)and roots of betel nut seedlings,while the iron content in L3 In addition,the manganese content in the leaves and roots of the betel nut seedlings under the treatment of zinc deficiency was reduced,which indicated that there was a certain complementary effect on the absorption and accumulation of iron and zinc in the betel nut seedlings,and the zinc deficiency also restricted the betel nut.Absorption of manganese.(4)In order to study the response of betel nut seedlings to iron and zinc deficiency stresses,this study performed transcriptome sequencing on the L1,L3,and R tissues of betel nut seedlings under different treatments with iron deficiency,zinc deficiency,and control,and counted the leaves of betel nut seedlings under different treatments.And the gene expression in the roots,and screened and compared the differentially expressed genes in the same tissues of the betel nut seedlings under the iron and zinc deficiency treatments and the control treatments.It was found that the differentially expressed genes in the leaves and roots of the betel nut seedlings under the iron and zinc deficiency treatments There were more down-regulated genes than up-regulated genes,indicating that iron and zinc deficiency treatments more inhibited the expression of related genes in betel nut seedlings;while iron and zinc deficiency treatments had significantly more differential genes in the roots of betel nut seedlings than in leaves,indicating that betel nut treatments Seedling roots are more sensitive to iron and zinc deficiency treatments than leaves.Then this study performed KEGG and KOG annotation analysis on differentially expressed genes.By analyzing the results of KEGG metabolic enrichment,we can find that some metabolic activities in the leaves and roots of betel nut seedlings are regulated by iron and zinc deficiency at the same time,and exhibit a certain tissue specificity,that is,in betel nut seedlings L1,L3 and R in iron deficiency Differentially expressed genes in the glutathione metabolism and flavonoid biosynthetic metabolism pathways were significantly enriched under zinc deficiency and zinc deficiency treatments,while the differentially expressed genes produced in L1 leaves were specific in the photosynthetic antenna protein pathway The significant enrichment.The results of KOG annotation found that the functional annotations of differentially expressed genes are widely distributed in carbohydrate transport and metabolism;post-translational modification,protein transport;inorganic ion transport and metabolism;secondary metabolite synthesis,transport and catabolism;signal transduction and other genes Function classification.(5)The physicochemical properties and evolutionary analysis of the proteins in the betel nut ZIP family showed that there are certain differences in protein sequences among the ten members of the ZIP family in betel nut.The expression of betel nut ZIP family genes in betel nut seedlings has certain tissue specificity,and most of the genes are expressed in the roots.At the same time,the ZIP family protein genes in betel nut L1,L3 and R are regulated by iron and zinc deficiency In different tissues,different genes respond differently to iron and zinc deficiency,and there are more genes in the root system that are regulated by iron and zinc deficiency.In summary,this study used betel nut seedlings as the research material,measured the biomass,chlorophyll content,chlorophyll fluorescence parameters and mineral element content of betel nut seedlings under nitrogen deficiency,iron deficiency,zinc deficiency and control treatments,and used transcriptome sequencing technology.The frontal gene expression in the leaves and roots of betel nut seedlings under the treatment of iron and zinc deficiency was analyzed,and the response mechanism of betel nut seedlings under the conditions of nitrogen,iron and zinc deficiency were analyzed at the physiological and transcriptional level.