Leaf variegation caused by plastome structural variation: an example from Dianella tasmanica

Area of Science:

• Plant genetics
• Molecular biology
• Genomics

Background:

• Variegated plants often have plastome mutations causing albinism.
• Plastome heteroplasmy is typically linked to small mutations.

Purpose of the Study:

• To identify the cause of albinism in variegated Dianella tasmanica plants.
• To characterize the plastome structural variation in albino sectors.

Main Methods:

• Analysis of plastome structure in variegated Dianella tasmanica.
• Gene expression profiling of plastid genes.
• Microscopic and ultrastructure examination of leaf tissues.

Main Results:

• Identified a large plastome structural variation (228,878 bp) in albino sectors, generated by intermolecular recombination.
• This variation resulted in the largest inverted repeat and smallest LSC region reported in land plants.
• Observed significant changes in plastid gene expression, including loss of essential genes, and poorly developed chloroplasts in albino tissues.

Conclusions:

• The identified plastome structural variation is responsible for albinism and loss of photosynthesis in Dianella tasmanica.
• Such large-scale structural variations may be common in variegated plants due to repeat elements in plastomes.