Leaf structure affects a plant's appearance: combined multiple-mechanisms intensify remarkable foliar variegation

Area of Science:

• Plant Biology
• Leaf Morphology
• Photosynthesis

Background:

• Foliar variegation is often misunderstood, impacting perceptions of leaf form and function.
• The study focuses on Blastus cochinchinensis, a species with striking juvenile leaf variegation.

Purpose of the Study:

• To investigate the structural mechanisms behind foliar variegation in Blastus cochinchinensis.
• To explore the ecophysiological implications of these variegation mechanisms.
• To test the generality of findings in Sonerila heterostemon and Kaempferia pulchra.

Main Methods:

• Comparative structural analysis of variegated and non-variegated leaves using microtechniques.
• Chlorophyll content and chlorophyll fluorescence measurements.
• Microscopic examination of leaf tissues.

Main Results:

• Variegation in Blastus cochinchinensis involves five combined mechanisms: epidermal, air space, upper mesophyll, chloroplast, and crystal (the latter two are novel).
• White (vw) areas exhibit distinct epidermal cells, air spaces, and modified mesophyll with fewer, larger chloroplasts.
• Despite structural differences, variegated and non-variegated leaves show similar total chlorophyll and maximum quantum yield of PSII (Fv/Fm), though vg shows higher Fv/Fm than ng.

Conclusions:

• Combined mechanisms, including novel crystal and chloroplast types, are key to Blastus variegation.
• Similar combined mechanisms in other species suggest this is a common phenomenon in nature.
• These intricate structural modifications likely compensate for photosynthetic loss and adapt to changing plant needs.