SSR Molecular Mapping And Genetic Analysis Of Weak Light Tolerance In Tomato(Lycopersicon Esculentum Mill.)

Weak light has become the important factors to restrict the production of the cultivation tomato in China.The main method to solve the problem at present is to identify and breed the strong weak light tolerance of tomato varieties.Different weak light tolerance of tomatoes were used to studied on physiological characteristics,photosynthetic characteristics,genetic law and molecular markers.It would provide theoretical foundations for identification and breeding the strong weak light tolerance of tomato varieties.The results were as follows:1.After shading tomato seedlings,the plant height/stem diameter,internodes length,net photosynthetic rate,Chla/b,soluble sugar,soluble protein,POD enzyme and malondialdehyde content changed in different degrees.(1)The plant height/stem diameter of the strong weak light tolerance of tomato lines QX and Xiaofen was significantly higher than that of the normal light tomato lines 16 L and Lnf.But the internodes length was the opposite.The height/stem diameter and internodes length of these four tomatoes lines both increased obviously under shading compare with normal light.(2)Chlorophyll a/b of the strong weak light tolerance of tomato lines QX and Xiaofen was significantly lower than that of the normal light tomato lines 16 L and Lnf under shading.But the degree of reduction of Chlorophyll a/b was the opposite.Chlorophyll a/b of these four tomatoes lines under shading was also significantly lower than that in normal light.So the Chla/b can be applied as identifying indexes of low light tolerance in seedling stage.The rangeability and genetic diversity of Chla/b were both the largest in lines of QX and 16 L.And Chla/b can be used as target traits to research weak light tolerance of tomato in genetic law and molecular markers.(3)Net photosynthetic rate of the four tomatoes lines uder shading was significantly lower than that in normal light.And the stomatal conductance and the content of soluble protein both decreased obviously under shading.But POD activity was the opposite.(4)Under shading,significant correlation were found between internodes length,soluble sugar,net photosynthetic rate and Chla/b.The internodes length and net photosynthetic rate can be used as auxiliary index to identify the weak light tolerance of tomato.2.Field investigation was carried out in strong weak light tolerance of tomato QX and weak light tolerance sensitivity of tomato 16 L and their offspring under shading.The results indicated that the genetic law of resistance to weak light weak light is two major genes plus additive-dominance-epitasis polygene model.3.There were 34 pairs of SSR polymorphic primers from screening for 202 pairs of primers.Finally,3 polymorphic primers were got from bulked segregation analysis.