芝麻黄化突变体YL1的叶片解剖学及光合特性

表型性状标记在作物遗传育种中具有重要的应用价值。在芝麻地方种质"庙前芝麻"中发现了能够稳定遗传的黄化突变体YL1,对该突变体的叶片解剖特征、光合特性及农艺性状的比较分析表明,突变体YL1黄化心叶和平展叶在各个发育时期的叶绿体结构均与同时期野生型存在明显差异,下表皮气孔保卫细胞数是正常叶的2倍左右。YL1的叶绿素a、总叶绿素、类胡萝卜素含量均只有同时期正常含量的30%~40%,叶绿素b含量只有正常叶的20%;光合速率在初花期及以前均显著低于同期正常叶,但到终花期与正常叶相当;YL1的生育期和初花期显著推迟,株高和单株蒴果数明显降低,每蒴粒数和千粒重略微降低。显微观察表明,YL1的叶绿体形态结构发育不规则,基粒和基粒片层数目明显少于野生型,使得叶绿素含量过低,属于叶绿体发育异常导致的叶绿素缺少型突变体。

Anatomical Structure and Photosynthetic Characteristics of a Yellow Leaf Mutant YL1 in Sesame (Sesamum indicum L.)

Phenotypic markers play an important role in crop breeding and genetic studies. A yellow leaf 1 (YL1) mutant has been found from sesame landrace‘Miaoqian Zhima’, which can be inherited stably. In this study, we compared YL1 mutant and its wild type (WT) in leaf anatomical structure, photosynthetic characteristics and biological traits. The structures of chloroplast in both top leaf and expanded leaves of YL1 were greatly different from those of WT at various development stages. The stomatal guard cell number in abaxial epidermis in YL1 was twice that in WT. In addition, the contents of chlorophyll a, total chlorophyll and carotenoid in YL1 were 30-40% of that in WT, and the chlorophyll b content in YL1 even as low as 20% of that in WT. At early flowering stage, YL1 showed significantly lower photosynthetic rate than WT, but the difference was not significant at end flowering stage. Compared with WT type, YL1 had significantly longer growth duration, delayed initial flowering time and shorter plant height, but capsules per plant and thousand-seed weight was slightly reduced. The microscopic observation revealed that YL1 is the chlorophyll deficiency mutant due to chloroplast defect, which was characterized with irregular chloroplast structure and reduced grana and granum lamella.