The Preliminary Study About A Yellow Green Aize Of Whole Growth Period

A yellow green maize (named yglml temporarily) was used as experimental material, and normal inbred lines Mo17and RP128were contrast material. The yellow green maize material was analysed from various aspects that were genetic trait and morphological trait, content of photosynthetic pigment and chloroplast ultra-structure and the number of chloroplast, photosynthetic characteristics and several intermediate metabolism products of chlorophyll biosynthesis. They aimed to understand the mechanism of a yellow green maize material. Their main results were as follows:1. The leaf color of maize yglml for F1and F2progeny on the hybrid combination yglml/478and yglml/RP128were observed, and found that maize yglml was controlled by recessive nuclear gene and the yellow green properties can be inherited stably. Meanwhile, the morphological trait of experimental material was measured, and found that maize yglml performed slender leaves, stem slender and etiolation in the whole plant.2. The photosynthetic pigment content of experimental material were measured at the jointing stage, tasseling stage and milk stage. It showed that chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content of maize yglml were significantly lower than normal inbred lines Mo17and RP128in these three periods, but the ratio of chlorophyll a/b and carotenoid/total chlorophyll content in this three stages were significantly higher than normal inbred lines Mo17and RP128. Maize yglml performed deficiency on total chlorophyll.3. Under the transmission electron microscopy, the chloroplast ultra-structure and the number of chloroplast were observed for experimental material at the booting stage. This results proved that the chloroplast structure existed obvious difference between maize yglml and normal inbred lines Mo17and RP128.The chloroplast of maize yglml had a lot of heavy particles of osmium and its chloroplast inner structure were loose, disorders and lots of big gap in its stroma lamellae with the trend of expansion. Maize yglml and normal inbred lines Mo17and RP128had no obvious difference about the number of chloroplasts in the mesophyll cell.4. The photosynthetic characteristics were measured for experimental material at the booting stage. The results showed that net photosynthetic rate (Pn), stomatal conductance (Cs) and intercellular co2concentration(Ci) of maize yglml were significantly lower than normal inbred lines Mo17and RP128, but the transpiration rate of mutant(Tr) were significantly higher than normal inbred lines Mo17and RP128. The analysis of light-response curve simulation parameters showed that the light compensation point, light saturation point, dark respiration rate and apparent quantum efficiency of maize yglml were higher than the normal inbred lines Mo17and RP128, but the maximum net photosynthetic rate were lower than the normal inbred lines Mol7and RP128. Light-response curves showed that the net photosynthetic rate of their three materials increased with the increasing of light intensity,and net photosynthetic rate of normal inbred lines Mo17and RP128were always higher than yglml in the same light intensity,and net photosynthetic rate of normal inbred lines Mo17and RP128rised significantly faster than maize yglml. However, maize yglml under the relatively strong light had the maximum net photosynthetic rate, and it had certain inhibitory effect for strong light. Meanwhile, net photosynthetic rate and stomatal conductance of experimental material were took for compared relations. The results showed that net photosynthetic rate were increased with the increasing of stomatal conductance, they had very significant positive correlation. CO2-response curves showed that maize yglml possess with lower net photosynthetic rate and higher CO2compensation point, but experimental material had almost the same CO2saturation point.5. Parameters of chlorophyll fluorescence kinetics was analyzed for maize yglml and normal inbred lines Mo17and RP128.The results showed that Fo, Fm, Fv/Fm, Fv’/Fm’,O PS Hand QP of maize yglml were lower than normal inbred lines Mo17and RP128, but Qn was higher than normal inbred lines Mo17and RP128.6. The relative content of chlorophyll synthesis intermediate metabolism products were measured for experimental material at booting stage, tasseling and silking stage. The results showed that the relative content of this three intermediate products from the second key intermediate product BPG to Urogen Ⅲ and CoprogenⅢ of maize yglml in this three periods were significantly higher than normal inbred lines Mo17and RP128,but the relative content of these three intermediate products Proto Ⅸ, Mg-Proto Ⅸ and Pchlide for maize yglml were significantly lower than normal inbred lines Mol7and RP128. They Indicated that chlorophyll biosynthesis metabolism pathway of maize yglml occurred to block, and blocked sites were from Coprogen Ⅲ to Proto Ⅸ.To sum up, the total chlorophyll content of maize yglml decreased, and the chloroplast ultra-structure of maize yglml had changed. Further analysis showed that maize yglml possess with the original light energy of electron transfer potential, lower capture efficiency and transformation efficiency, lower energy allocation and utilization and higher heat dissipation. These characters were consisted with lower photosynthetic capacity of maize yglml. Chlorophyll synthesis intermediate metabolism products of experimental material were analysed. The results Indicated that chlorophyll biosynthesis metabolism pathway of maize yglml occurred to block, and blocked sites were from Coprogen Ⅲ to Proto Ⅸ, and the metabolic changes could lead total chlorophyll content of maize yglml to decrease.