一个新的玉米黄化突变体的初步研究

对新发现的玉米黄化突变体的形态特征进行观察,发现突变体茎秆纤细,叶片细长。光合色素含量测定结果表明,突变体叶绿素a(cla),叶绿素b(clb),类胡萝卜素(caro)和总叶绿素(chl)含量均极显著低于正常自交系,caro/chl显著高于正常自交系,推测突变体为总叶绿素缺乏型突变。用透射电镜对叶绿体超微结构进行观察,发现突变体叶绿体内部有较多嗜锇颗粒,叶绿体结构松散紊乱,基质片层间隙大,有扩张趋势,但基粒数目及垛叠层数在突变体与正常自交系间无明显差异,叶绿体数目在突变体与正常自交系间无显著差异。说明该突变体叶色改变可能与光合色素含量的减少及叶绿体基质片层的结构有关或与叶绿体内大量嗜锇颗粒的存在有关。

THE PRELIMINARY STUDY OF A NOVEL YELLOW-GREEN LEAF MUTANT IN MAIZE

We investigated the newly discovered yellow-green leaf mutant of maize for morphological characteristics. We found that its stem was slender and its leaf was narrow with long blades. We calculated their photosynthetic pigment contents.The results indicated that chlorophyll a (cla), chlorophyll b (clb), carotenoids (caro) and total chlorophyll (chl) in this mutant were significantly lower than the normal inbred lines. The caro /chl in the mutant was significantly higher than the normal inbred lines, indicating that the decrease in chlorophyll content of the mutants was greater than that in the carotenoid content. Therefore, the plant etiolation trait was mainly attributed to the reduction of the total chlorophyll content, but not the decrease of the carotenoid content. Thus, the yellow-green leaf mutant was a kind of the total chlorophyll deficient mutant. The ultrastructure of chloroplast in the mutant and normal inbred line were observed with the electron micrograph. Compared with the normal inbred lines, chloroplasts in the mutant had a lot of osmiophilic granules. Its inner structure was loose and disorder, and its stroma lamellae had lots of big gap with a trend of expansion. However, the grana stacked layers and the base particle number in the mutant and normal line had no obvious difference. Meanwhile it was observed that there were no significant differences in the chloroplast number. The leaf colour change of this mutant may relate to the decreasing of photosynthetic pigment contents, the structure of chloroplast stroma lamellae or lots of osmiophilic particle within chloroplasts.