低氮条件下外源褪黑素调控青稞幼苗生长和氮素吸收利用的生理与分子机制OA

In this study,the highland barley cultivar Longqing No.1 was used as experimental material to investigate the effects of exogenous melatonin application on the growth,nitrogen uptake and expression of related genes in highland barley seedlings under different nitrogen levels.The results showed that melatonin treatment significantly promoted the growth of both aboveground and underground parts of high-land barley seedlings under low nitrogen conditions,and improved root morphology,including root length,root vol-ume,root surface area,root diameter and root tip number.Meanwhile,the total nitrogen content and nitrogen uptake in the aboveground and underground parts of seedlings were increased.Under low nitrogen conditions,the relative expression levels of glutamine synthetase gene(HvGS2)and ni-trate transporter genes(HvNRT3.1 and HvNRT3.3)in the aboveground parts of melatonin-treated seedlings were significant-ly higher than those in the control group(P<0.05).Similarly,the relative expression levels of HvNRT3.1 in underground parts were also markedly upregulated compared with the control(P<0.05).These findings indicate that melatonin can sys-tematically enhance nitrogen reduction and assimilation capacity in both aboveground and underground tissues,thereby jointly improving nitrogen uptake and utilization efficiency of plants.In conclusion,exogenous melatonin can effectively al-leviate low-nitrogen stress and promote the growth of highland barley seedlings by optimizing root architecture and upregulat-ing the expression of genes involved in nitrogen uptake and metabolism.This study provides a theoretical basis for high-yield cultivation of highland barley under low nitrogen conditions.