Photosynthetic Charateristics And Primary Mapping Of Related Gene In Purple Pepper

The purple pepper CS3?purple-leaf,upwards-fruit,high plant and late-maturing?was crossed with green pepper LS1?green-leaf,downwards-fruit,medium plant and medium-maturing?to construct population.And then,the leaf pigments,photosynthetic characteristics and the optimum light response model of seven peppers with different purple levels namely Z-1,Z-2,Z-3,Z-4,Z-5,Z-6 and Z-7 in F₂ population were studied.Based on the segregation of parents,F₁ and F₂ populations,the purple-leaf traits genetic laws were analyzed and the related gene was preliminarily located.The main results are as follows:1.When compared to pure green pepper,the purple pepper has a higher anthocyanin,chlorophyll b and total pigment contents,and a lower chlorophyll a/b value.With the exception of Z-6,the net photosynthetic rate?P_n?,stomatal conductance?G_s?and transpiration rate?T_r?of purple peppers keep rising without saturation or light inhibition phenomena when the photosynthetic active radiation came to 2 000?mol·m^-2·s^-1.Under the photosynthetic effective radiation of 2 000?mol·m^-2·s^-1,the highest P_n value was 20.16±0.58?mol·m^-2·s^-11 for Z-4,while the highest water use efficiency value was 2.02±0.01?mol·mmol^-11 for Z-5.2.The modified rectangular hyperbolic model have a higher accuracy with the R²?0.995 when be used to fit the light response process of seven peppers with different purple level.So the modified rectangular hyperbolic model is more suitable for fitting the purple pepper light response curve as it could provide values closer to measured ones and more parameters information.3.It was found that the leaves of the F₁ population were all with purple.In the F₂ population,pepper plant with purple leaves were 381,and 132 pepper plants with green leaves.The segregation ratio of leaf color was 3 purple?1 green with a tested?²value of 0.146.It means the genetic inheritance of purple-leaf traits fit with the Mendelian inheritance rules.And then Bulked segregant RNA-Seq was used to locate the purple-leaf related genes in purple peppers.They were preliminarily located in three regions on the chromosome 10,that is to say 1.28cM-1.9cM,4.0cM-6.8cM,15.6cM-20.1cM,and six candidate genes were selected from those regions,and further analysis revealed that Capana10g001785 was only one expressed in pepper leaves.To sum up,the purple pepper has a high anthocyanin content and could well adapt to strong light.The water use efficiency of Z-5 ranked the highest in different purple degree peppers,which means it facilitates thescreening of water-saving materials.The modified rectangular hyperbolic model is the best model for fitting the light response process of purple peppers.The presence or absence of purple traits in pepper leaves was controlled by one pair of dominant genes.The target gene was located on Chromosome 10.The candidate gene Capana10g001785,who only expressed in the leaves in the six gene will be the focus of further study.