Variable Leaf Epidermal Morphology in TNT1 Insertional Mutants of the Model Legume Medicago Troncatola

ABSTRACT

In this report some typical leaf morphological characteristics of M. truncatula mutants generated by a Tnt1 retrotransposon insertion mutagenesis were evaluated and summarized. It was found that all the examined leaf epidermal parameters were strongly influenced in the Tnt1 mutant lines. Epidermal cells varied in shape and size, and diversified in the patterns of cell walls. Although the leaves of all mutant plants were amphistomatic, stomata were more abundant at the lower (abaxial) leaf surfaces than the upper (adaxial) leaf surfaces. On the other hand, the number of stomata on both leaf surfaces varied widely among different Tnt1 lines. Based on these observations, we conclude that most of the observed mutant phenotypes were caused by the Tnt1 insertions. In addition, the evaluated leaf epidermal features can be reliably applied for phenotypic profiling of M. truncatula mutant lines. Morphological variables in leaf epidermis in all the screened mutants demonstrated that Tnt1 is a very efficient mutagen, confirming that Tnt1 gene tagging strategy is one of the most valuable systems for legume functional genomics.

Keywords:

• Medicago truncatula
• Tnt1 retrotransposon
• insertion mutagenesis
• leaves
• epidermis
• stomata