Selection Of Leaf Yellow Mutant Barley And Characteristics Of Its Nitrogen Utilization

Nitrogen is one of an essential macronutrients for plant growth and development,also as the premise of ensuring of high yield of crops.Currently,some reports have been carried out on the analysis about gene function of crop nitrogen metabolism,and a few reports analyzed the influence mechanism of a specific gene on the nitrogen metabolism regulation network.The current researches mainly focused on nitrate transporters,nitrogen assimilation of enzymes.But nitrogen metabolism is an extremely complicated metabolic pathways in plants and the existing research is not enough to clearly and accurately clarify nitrogen metabolism physiological and biochemical process.In this study,the barley leaf yellow mutant was screened from 3304 barley materials via SPAD（single-photon avalanche diode）values measurement.Their chromosomal morphological characteristics were analyzed in order to clear mutant type.The nitrogen use efficiency features and photosynthetic efficiency index were analyzed after combined with its parent material Baudin and CN4027,marking the barley leaf yellow mutant materials on the response characteristics of photosynthetic reaction more clear,the main conclusions are as follows:（1）Field experiments showed that SPAD value among tillering stage only CN0126was 13.9 and the remaining materials were between 20 and 56.During the whole growth stage,CN0126 presented obvious difference characteristics with the parents Baudin and CN4027,which contained yellow-green leaf,growth retardation and so on.The above traits,accounted for that CN0126 as a leaf yellow mutant.In addition,chromosome of CN0126 is complete,the FISH（Fluorescence in Situ Hybridization）probe（CTT）₅,（AGG）₅,Oligo-442a01 and Oligo-Hv T01.1 signal loci and strength with on obvious difference between the parent materials,explaining that the mutation types of CN0126 is small fragments in DNA level variation or single-base mutation in nucleotide level.（2）Under different nitrogen levels,dry weight of root,stem and leaf in CN0126 were significantly lower than Baudin and CN4027.Under normal and high nitrogen levels,the leaf nitrogen content of CN0126 was significantly lower than that of Baudin and CN4027.The soluble protein content of CN0126 was significantly lower than that of Baudin and CN4027 at 3 nitrogen levels.The mutation of CN0126 resulted in the decrease of nitrogen assimilation efficiency in leaves and further affected the accumulation of plant matter.（3）14 days before the nitrogen treatment under different nitrogen levels and 14 days later under normal nitrogen and high nitrogen level,the content of chlorophyll a,chlorophyll b,carotenoid in CN0126 were significantly lower than parent materials Baudin and CN4027.Under different nitrogen levels,the net photosynthetic rate of CN0126 was not significantly different from that of CN0126 at the low nitrogen level during the 28 days of nitrogen treatment,and the net photosynthetic rate of CN0126 in other conditions was significantly lower than that of Baudin and CN4027.Most of these conditions,the PSII CN0126 maximum photochemical quantum yield Fv/Fm,photochemical quenching coefficient q P value,ETR electron transfer efficiency,the actual original light capture efficiencyΦPSII value of CN0126 significantly lower than that of Baudin and CN4027.Compared with Baudin and CN4027,CN0126 with bad morphology and little number of chloroplasts,and thylakoids.The above change of properties in CN0126 mutations may caused by its chloroplast,thylakoid morphological changes,which influence the synthesis of photosynthetic pigment,and further affect photosynthesis and chlorophyll fluorescence properties.