Effects Of Exogenous GA And Inhibitor Paclobutrazol On The Growth Of Pepper (Capsicum Annuum L.) Seedlings Under Low Light Stress

In this study,pepper（Wanfeng Big Bell Pepper）was used as the test material for shading treatment(the actual light intensity during the test was 250-370μmol·m^-2·s^-1,and the light intensity in the shading area was 50-90μmol·m^-2·s^-1.The highest temperature in the greenhouse during the day is 27±1℃,the lowest temperature at night is 12±1℃),and the processing time is 20 days.Exogenous gibberellin and its inhibitor paclobutrazol were sprayed under low light conditions to analyze and study the morphology,physiological characteristics,biochemical indicators,rapid chlorophyll fluorescence dynamics,expression of related genes and the difference of endogenous hormones in pepper seedlings.So as to provide help for low light tolerance cultivation and variety breeding of pepper.The main findings are as follows:1.Under the stress of low light,the plant height of pepper seedling was higher than that under normal light;and the stalk was smaller than that under normal light.Under the stress of low light,the thin and weak plants tended to lie down easily.2.The weak light stress led to a decrease in the PIabs value of the performance index based on the absorption of light energy,and the application of exogenous paclobutrazol increased the PIabs value.3.The chlorophyll content of pepper seedling leaves under low light stress is higher than that under normal light,and the application of exogenous paclobutrazol was further increased the chlorophyll content of pepper seedling leaves;the chlorophyll a/b content of pepper seedling leaves under low light was lower than that under normal light.The chlorophyll a/b content is low after spraying exogenous paclobutrazol.4.With the enhancement of low-light stress,the content of malondialdehyde in the leaves of pepper seedlings gradually increased compared with that under normal light,indicating that the active oxygen metabolism in the plant changed,the plasma membrane was damaged,and the related physiological and biochemical reactions were abnormal;pepper under low light,the content of proline in the leaves of the seedlings showed a trend of decreasing first and then increasing.After spraying with exogenous paclobutrazol,the proline content was higher than that of the weak light control;the content of soluble protein in the leaves of pepper seedlings increased with time,and exogenous spraying under low light paclobutrazol increased the soluble protein content of plants.5.Bioinformatics analysis of GIDs and GAIs in the pepper genome,construction of phylogenetic trees and protein structural prediction.6.Quantitative Real-time PCR test showed the expression levels of gibberellin-related genes GID1,GID2 and GAI in pepper seedlings.Under low light stress,the expression levels of GID1 and GID2 increased,while the expression level of GAI decreased.Among them,exogenous gibberellin and paclobutrazol have opposite effects on GID1.