Mechanism Analysis The Growth Response Of Phyllostachys Edulis Seedling To Different N Forms

Phyllostachys edulis is a bamboo species with important economic,ecological and cultural values,widely distributed in the subtropical region of southern China.Nitrogen（N）is one of the mineral nutrients that plants need the most.Among them,ammonium（NH₄⁺）and nitrate（NO₃^-）are the main forms of inorganic nitrogen absorbed by plants.In order to further clarify the nitrogen form preference of Ph.edulis seedlings,the growth response characteristics and absorption capacity differences of Ph.edulis seedlings under different hydroponic conditions were studied in this paper.At the same time,the biological information analysis and transcriptome analysis under different nitrogen forms of the ammonium transporter gene and nitrate transporter gene in Ph.edulis was studied.The main results are as follows:（1）The biomass and the nitrogen content of Ph.edulis under ammonium nitrogen treatment are superior to the nitrate nitrogen treatment of equal concentration.The biomass and root-stem ratio decrease with the increase of nitrogen treatment concentration,but the nitrogen content of each part increases with the nitrogen concentration significantly.Root length,root surface area and root volume are important factors that determine the nutrient absorption capacity of Ph.edulis roots.Increased nitrogen concentration will inhibit root growth.Ph.edulis growth and nitrogen accumulation showed ammonium nitrogen preference,but when the concentration was too high,it showed an inhibitory effect on plant growth.The absorption capacity of Ph.edulis for ¹⁵NH₄⁺is greater than ¹⁵NO₃^-,and the K_m value and V_max of NH₄⁺absorption are greater than NO₃^-,indicating that the growth of Ph.edulis seedling root system to NH₄⁺and the transportation/absorption capacity are stronger.（2）20 AMT genes and 6 NRT genes were identified in the Ph.edulis genome,AMT protein genes were divided into 3 subgroups,and NRT proteins were divided into 2 subgroups;gene structure and motif analysis showed that most AMT genes had a relatively conservative exon/intron arrangement and motif composition.The difference in the number of NH₄⁺and NO₃^-transport carrier proteins formed during long-term evolution may be the reason for the difference in N form absorption capacity of Ph.edulis.（3）Differential profiling analysis of different nitrogen forms yielded raw data of about 6G.Compared with contrast（CK）,NH₄NO₃ and NO₃^-treatments,NH₄⁺treated Ph.edulis seedlings had 1258,196 and 219 respectively genes were up-regulated,2921,352 and 354 were down-regulated.Through trend analysis,we learned that genes in each module were significantly enriched in metabolic pathways,biosynthesis of secondary metabolites,carbon metabolism,amino acid biosynthesis,plant hormone signal transduction,photosynthesis,etc.Gene expression,but no genes with significantly different expressions in the nitrogen metabolism pathway were found.The research results further confirmed the NH₄⁺preference of Ph.edulis,and provided evidence support at the physiological and molecular genetic level,which can provide a theoretical basis for the scientific use of N fertilizer in Ph.edulis.