Wolffia australiana belongs to the subfamily Lemnaceae within the family Araceae. It is not only the smallest but also the simplest angiosperm. The tiny ellipsoidal morphological structure of Wolffia can be summarized by the "four ones": about ONE mm in length and diameter, ONE leaf (although a growth tip and multiple branches are enclosed inside the ellipsoidal leaf), and usually only ONE stamen and ONE pistil when flowering.
Records of this type of duckweed plants in China can be traced back to the Spring and Autumn Period and the Warring States Period. People assigned the name according to its growth characteristics: "Floating without roots on the water surface, so it is called Ping” (meaning even to the water level. the duckweeds). The ancients have realized the characteristics of duckweed plants that quickly produce new individuals: "The duckweed breeds so well that it produces seven descendants overnight". But regarding the origin of the duckweed, some people proposed romantic imagination of poplar flowers falling into the water and turning into duckweed. Literati had analogized the uncertainty of life with the rootlessness of the duckweed (Ping): "Every piece of duckweed floats down to the sea; People will always meet each other somewhere".
In the field of modern science, there have been two research upsurges on duckweed. The first began in the 1950s, represented by Swiss botanist Elias Landolt. He collected and preserved more than 1000 duckweed (including Wolffia) germplasm resources, and described the morphological characteristics of the duckweed in detail. William Hillman, an American plant physiologist, tried to use duckweed as a model organism to study plant physiology and biochemistry. The second was represented by the American molecular biologist Eric Lam, hoping to take advantage of the rapid growth of duckweed plants to develop it into a bioreactor. The number of scientists participating in this upsurge has increased, and the genome sequencing and genetic modification technology of several duckweed (including Wolffia) species have also been established.
The original intention of the establishment of this website is different from the two research upsurges mentioned above. We hope to build a data sharing platform based on the research findings obtained by our team and make it a communication space for people interested in exploring the basic principles of plant morphology.
Our research on Wolffia can be dated back to 1994. At that time, Dr. Shu-Nong Bai, who had just finished his postdoctoral training at the UC Berkeley, introduced his newly developed concept "plant developmental unit" to Prof. Da-Ming Zhang, a classmate of Shu-Nong Bai during their PhD studies at the Institute of Botany, Chinese Academy of Sciences (CAS). Prof. Da-Ming Zhang proposed that Wolffia could be used as an experimental system to test the concept of "plant developmental unit", and he was the first to start a new attempt to establish Wolffia as a model plant. A few years later, Da-Ming Zhang at the Institute of Botany, led his students to complete the collection of Chinese Wolffia germplasm resources and laboratory aseptic culture and preservation. However, his efforts were unsustainable due to the inability to achieve flowering induction in the laboratory in Beijing.
Seeing that his friend’s attempts were in trouble, Dr. Shu-Nong Bai, who had already moved from the Institute of Botany to the Peking University (PKU), learnt a new technology called microfluidic from a leading scientist, Professor Yong Chen of the Ecole Normale Supérieure Paris, when both of them were members of the Center for Theoretical Biology (later renamed as the Center for Quantitative Biology, CQB) at PKU. Understanding the potential advantages of microfluidic technology in high-throughput optimization of culture conditions, they proposed to the center colleagues to expand "microfluidics" to "millifluids" to optimize the flowering induction conditions of microfluidics. So the concept of "plant-on-chip" came into being in the CQB. The experiments were launched in the laboratory of Shu-Nong Bai in the School of Life Science (SLS) in 2007, in collaboration with Prof. Qi Ouyang and Prof. Chun-Xiong Luo in the School of Physics. Unfortunately, although this attempt made people gain a lot of first-hand knowledge about Wolffia morphogenesis, the goal of flower induction was not achieved by 2010.
Around 2013, Prof. Hong-Wei Hou from the Institute of Hydrobiology of CAS was convinced to join the research team of Wolffia because of his laboratory located in Wuhan (Wolffia can bloom every year in the water body of the Wuhan Botanical Garden). Prof. Da-Ming Zhang gifted Prof. Hou all his Wolffia samples he had carefully collected for many years.
In 2016, due to various coincidences, Wolffia research has reappeared in the form of "crowdfunding" (which corresponds to the meaning of "People will always meet each other somewhere"). The main motivation for this restart comes from the enthusiasm for exploring the unknown nature, the feelings for the alma mater of PKU, and the friendship and trust. All the participants this time contributed their efforts voluntarily. Prof. Hong-Wei Hou laboratory of the Institute of Hydrobiology of CAS provided sequencing materials; Dr. Feng Li (former PhD student in Shu-Nong Bai Lab at PKU) led the RDFZ (the High School Affiliated to Renmin University of China) students to establish a microfluidic culture system for Wolffia with the help of Prof. Chunxiong Luo's lab, and successfully induced the flowering of Wolffia under the stable laboratory conditions; Dr. Feng Li cooperated with the team of Dr. Yi-Qun Liu of the Experimental Instrument Center of SLS of PKU, and with the help of RDFZ students, completed a detailed description of the morphological construction of Wolffia; Mr. De-Peng Wang, the co-founder and CEO of Grandomics, generously offered free sequencing of the Wolffia genome, and completed the genome assembly analysis and other genomic analysis with Prof. Ling Li's lab at the Mississippi State University; Prof. Zhu-Kuan Cheng at the Institute of Genetics and Development of CAS determined the chromosome number of Wolffia; Prof. Fu-Chou Tang’s lab (SLS and BIOPIC, PKU) completed RNA-Seq of single Wolffia plantlet. Prof. Yi-Hua Zhou’s lab at the Institute of Genetics and Development of CAS completed the analysis of Wolffia vascular development and the functional verification of related genes; Dr. Huan Liu's team (BGI) completed the first single-cell RNA-seq of Wolffia; Prof. Xiao-Dong Su Lab at the SLS of PKU completed the protein structure prediction of unique Wolffia genes; Prof. Ge Gao Lab (BIOPIC, PKU) performed network structure analysis on the expression profile data related to flowering induction and constructed this website (Wolffiapond.net). All these works were done by amateurs or professional researchers in their spare time without any special funding support. The results of this "crowdfunding" research have been published on PNAS Nexus with the title of “The Plant-on-Chip: Core Morphogenesis Process in the Tiny Plant Woffila australiana”. All relevant data are deposited in this website. We hope that in the future, more people interested in exploring the basic principles of plant morphology will be inspired by the information on this website and join in the renaissance of plant science in the future.
- Bai, S. (1999) Phenomena, interpretation of the phenomena and the developmental unit in plants. in Advances of Botany, Vol II, 52-69, ed. Li, Chensheng. Higher Education Publish House, Beijing (in Chinese)
- Bai SN (2019) Plant Morphogenesis 123: A Renaissance in Modern Botany? Sci. China Life Sci.