Saturday, 16 July 2016

The duckweed Wolffia microscopica: A unique aquatic monocot

Published Date

January 2015, Vol.210:31–39, doi:10.1016/j.flora.2014.10.006

Title

The duckweed Wolffia microscopica: A unique aquatic monocot ☆

Author

K. Sowjanya Sree^a,^,

Satish C. Maheshwari^b^,

Karoly Boka^c^,

Jitendra P. Khurana^d^,

Áron Keresztes^c^,

Klaus-J. Appenroth^e^,

aAmity Institute of Microbial Technology, Amity University Uttar Pradesh, Noida 201303, India
bBiotechnology and Bioinformatics Laboratories, Centre for Converging Technologies, University of Rajasthan, Jaipur 302004, India
cDepartment of Plant Anatomy, Eötvös Loránd University, H-1117 Budapest, Hungary
dDepartment of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India
eInstitute of General Botany and Plant Physiology, University of Jena, Dornburger Str. 159, D-07743 Jena, Germany

Received 10 March 2014. Revised 5 September 2014. Accepted 18 October 2014. Available online 1 November 2014. Edited by Shahin Zarre

Highlights

•
Vegetative and generative propagation in the fast growing W. microscopica coexist.
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A unique structure, pseudoroot, might contribute to its fast multiplication.
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Knowledge of morphology and anatomy will increase its potential use in molecular and evolutionary studies as a model.
•
Frequent flowering overcomes disadvantages of other model duckweeds.

Abstract

The rediscovered species Wolffia microscopica (Griff.) Kurz, endemic to India, Pakistan and Bangladesh, shows several features that make it unique in comparison to other duckweeds, even to other species of the genus Wolffia. During vegetative propagation, the daughter fronds are produced by budding within a single pouch of the mother frond. Several generations of fronds and their initials exist in union with the parent frond at a given time. Most strikingly, almost all the fronds flower, both in nature and under controlled culture conditions. Thus, in contrast to all other duckweed species, generative propagation is as important as vegetative propagation, which opens the opportunity for artificial breeding. Moreover, flower development on both mother and daughter fronds was observed at the same time. In contrast to all other duckweed species, fronds of W. microscopica often possess a ventral projection of varying length ranging from an almost flat appearance of the ventral surface to a length of 4 mm. Absence of root cap, root hairs and vascular tissue demonstrate that this ventral protrusion is not a root and accordingly we name this special structure “pseudoroot”. The high number of chloroplasts in the pseudoroot may result in higher capacity of photosynthesis without increasing the frond area which covers the water surface. Thus we propose that the pseudoroot serves to be advantageous to W. microscopica in multiplying at a faster rate in comparison to other duckweeds.