| Chemical mutagenesis is an effective method in rice breeding.Leaf color mutation is a phenotype with high frequency in chemical mutagenesis,especially the highest frequency of lethal albino mutation in leaves.Most leaf color mutants are not able to grow and complete their life cycle due to the influence of photosynthesis,so they have no application value.Three leaf color mutants,mQ64,m3038 and m4607,were obtained by chemical mutagenesis.In this study,the photosynthetic physiological characteristics of these three pale yellow mutants were studied in order to study the molecular mechanism and utilization of leaf color mutants which can grow and develop normally.Value provides new scientific support.The main results are as follows:1.Compared with wild type,the chlorophyll content of mutated yellowish leaf color mutant decreased to some extent,the total chlorophyll content of mQ64,m3038 and m4607 was 64.8%,53.6% and44.8% of that of wild type respectively,and the content of chlorophyll in the mutated mutant was 64.8%,53.6% and 44.8% of that of wild type,respectively.The results showed that the change of leaf color to yellowish leaf by chemical mutagenesis was due to the decrease of chlorophyll content.2.By comparing the precursor content of chlorophyll synthesis pathway,it was found that the content of m3038 mutant mQ64 andm3038 was significantly lower than that of wild type,so the content of coprogenitor ? in mutant M3038 was significantly lower than that in wild type.The decrease in the efficiency of synthesis of fecroporphyrin? from uroporphyrin ? was the reason for the decrease of chloroplast content in the two mutants.The urinary porphyrin ?(Urogen ?)content in m4607 was significantly decreased,while that in m4607 was significantly lower than that in control group.Therefore,the abnormal synthesis pathway of chloroplast in the mutant occurs in the synthesis of uroporphyrin ?(Urogen ?)by PBG.3.The net photosynthetic rate of mutant mQ64,m3038 and m4607 was lower than that of wild type under weak light condition.The net photosynthetic rate of mutant mQ64 and m3038 was higher than that of wild type under high light intensity,and the net photosynthetic rate of mutant m4607 was lower than that of wild type.4.The results showed that the mutant material mQ64,m3038,Fv '/Fm',?PS II,qP and ETR were all higher than those of wild type,and qN was lower than that of wild type.Higher photoenergy conversion efficiency and higher electron transfer rate;m4607 's Fv'/ Fm ',?PS?,and qN are all lower than that of wild type,and the values of qP and ETR are higher than that of wild type,indicating that the higher electron transfer efficiency is not sufficient to compensate for the reduction of light-capturing capacity.5.The phenotypic comparison showed that the phenotypes ofmutant mQ64 and m3038 were basically the same as those of wild type,while the phenotype of m4607 was smaller than that of wild type.It can be seen from the above results that mQ64 and m3038 have the characteristics of high light efficiency under the condition of strong light,the growth and development is normal,and the leaf-color mark character of the rice sterile line can be used as the hybrid seed production,so that the impurity removal cost of the seed field is reduced,and the seed purity of the hybrid seed production is improved.And m4607,because the content of chlorophyll is too low,the photosynthetic rate is lower than that of the wild type,so that the growth amount is reduced,and the m4607 can not be applied to the hybrid rice as a leaf color marker. |
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