一个空间诱变的温度敏感型冬小麦叶绿素突变体的初步研究

A TEMPERATURE-SENSITIVE WINTER WHEAT CHLOROPHYLL MUTANT DERIVED FROM SPACE MUTAGENESIS

通过空间诱变创制的冬小麦叶绿素突变体Mt18的叶色表现为对温度敏感的绿-白-绿的变化过程,能够正常成穗结实,但其株高、有效株穗数、穗长、株粒数、株粒重、千粒重都显著低于原始亲本。电镜观察表明,变白前期突变体叶绿体数目和结构与原始亲本未见明显差异;变白期突变体叶绿体内基粒类囊体数和基粒片层数较少,甚至完全消失,基质类囊体清晰可见;复绿期突变体叶绿体数目少于原始亲本,细胞内大部分叶绿体结构恢复正常。叶绿素荧光动力学参数分析表明,当光照强度为110μmol.m-2.s-1时,突变体Mt18的非光化学淬灭系数显著低于原始亲本,非调节性能量耗散的量子产量显著高于原始亲本,而光系统Ⅱ的最大量子产量、光系统Ⅱ的潜在活性、光化学猝灭系数、实际量子产量和调节性能量耗散的量子产量在不同时期变化不同。另外,不同的光照强度条件下,突变体的电子传递速率、光化学淬灭系数、实际量子产量的变化也不相同。上述结果证实,温度敏感型冬小麦叶绿素突变体Mt18的叶片颜色和光合特性随着叶绿体超微结构的变化而相应改变,变白期叶绿体超微结构存在明显缺陷,光合效率显著降低,较高的光照强度对突变体影响较大,导致产量相关性状显著降低。

A temperature-sensitive winter wheat（Triticum aestivum L.） chlorophyll mutant Mt18,induced by spaceflight mutagenesis,was studied on agronomic traits,ultrastructure of chloroplast and photosynthesis characteristics.The leaf color of the mutant Mt18 showed changes from green to albino and back to green during the whole growth period.Plant height,productive tillers,spike length,grains and grain weight per plant,and 1000-grain weight of the mutant were lower than those of the wild type.The ultrastructural observation showed that no significant difference was found between the mutant and the wild type during prior albino stage,however,at the albino stage the number of granum-thylakoids and grana lamellae became fewer or completely disappeared,but the strom-thylakoid was obviously visible.After turning green,the structure of most chloroplasts recovered to normal,but number of chloroplast was still lower than that of the wild type.When exposed to photosynthetic active radiation（PAR） of 110μmol.m-2.s-1,the non-photochemical quenching（NPQ） of mutant was significantly lower than that of the wild type,and the non-regulated energy dissipation （YNO） was significantly higher than that of the wild type,while the change of the maximum photosystem Ⅱquantum yield（Fv /Fm）,potential activity of photosystem Ⅱ（Fv /Fo）,photochemical quenching（qP）,effective quantum yield （YPSⅡ） and regulated non-photochemical energy dissipation（YNPQ） were different at various stages.In addition,the differences of the electron transport rate（ETR）,photochemical quenching（qP）,and effective quantum yield（YPSⅡ） between mutant and wild type varied under different PAR conditions.It was concluded that with the change of chloroplast ultrastructure,the leaf color and photosynthesis of the wheat mutant Mt18 change correspondingly.The chloroplast ultrastructure was obviously different from that of wild type,and the photosynthetic efficiency reduced significantly.The higher photosynthetic active radiation had tremendous impact on the mutant at albino stage,and yieldrelated traits reduced significantly.