Leicester, United Kingdom
March 20, 2009
- Plant biologists discover gene
that switches on 'essence of male'
- Study identifies role of gene responsible for plant sperm
production
Biologists at the
University of Leicester have published results of a
new study into plant sex – and discovered that a particular gene
switches on 'the essence of male'.
The study takes to a new level understanding of the genes needed
for successful plant reproduction and seed production.
Professor David Twell and colleagues in the Department of
Biology at the University of Leicester reported the discovery of
a gene that has a critical role in allowing precursor
reproductive cells to divide to form twin sperm cells.
Their study is reported in the journal Public Library of Science
Genetics (PLoS Genetics) and was funded by the
Biotechnology and Biological
Sciences Research Council (BBSRC).
Professor Twell said: "Flowering
plants, unlike animals require not one, but two sperm cells for
successful fertilisation. One sperm cell to join with the egg
cell to produce the embryo and the other to join with the
central cell to produce the nutrient-rich endosperm tissue
inside the seed. A mystery in this 'double fertilisation'
process was how each single pollen grain could produce the pair
of sperm cells needed for fertility and seed production.
"We now report the discovery of a dual role for DUO1, a
regulatory gene required for plant sperm cell production. We
show that the DUO1 gene is required to promote the division of
sperm precursor cells, while at the same time promoting their
specialised function as sperm cells. It effectively switches on
the essence of male.
"We show that DUO1 is required for the expression of a key
protein that controls cell division and for the expression of
genes that are critical for gamete differentiation and
fertilisation.
"This work provides the first molecular insight into the
mechanisms through which cell cycle progression and gamete
differentiation are coordinated in flowering plants.
"This knowledge will be helpful in understanding the mechanisms
and evolution of gamete development in flowering plants and may
be useful in the control of gene flow and crossing behaviour in
crop plants."
The researchers also report on the
presence of genes closely related to DUO1 in a wide variety of
flowering plants and even in lowly land plants such as moss,
which suggests that DUO1 may be part of an ancient sperm cell
regulatory network that evolved even before pollen and flowers
appeared on the scene.
Interestingly, DUO1 is also related to a super class of Myb
regulator proteins also present in animals that have an
important role in controlling cell proliferation and that are
implicated in certain human cancers such as leukemias. So like
animal cell Myb proteins, DUO1 is needed for control of cell
proliferation, but DUO1 is distinguished by its specific role in
plant reproduction, namely its dual role in sperm cell
production and switching on their ability to fertilize.
Professor Twell added that the study could help to unravel the
evolutionary origins of plant sperm cells and provide new
molecular tools for the manipulation of plant fertility and
hybrid seed production – as well as to control gene flow in
transgenic crops where the male contribution may need to be
eliminated.
Abstract Background
The unique double fertilisation mechanism in flowering plants
depends upon a pair of functional sperm cells. During male
gametogenesis, each haploid microspore undergoes an asymmetric
division to produce a large, non-germline vegetative cell and a
single germ cell that divides once to produce the sperm cell
pair. Despite the importance of sperm cells in plant
reproduction, relatively little is known about the molecular
mechanisms controlling germ cell proliferation and
specification.
Abstract Findings
Here, we investigate the role of the Arabidopsis male
germline-specific Myb protein DUO POLLEN1, DUO1, as a positive
regulator of male germline development. We show that DUO1 is
required for correct male germ cell differentiation including
the expression of key genes required for fertilisation. DUO1 is
also necessary for male germ cell division, and we show that
DUO1 is required for the germline expression of the G2/M
regulator AtCycB1;1 and that AtCycB1:1 can partially rescue
defective germ cell division in duo1. We further show that the
male germline-restricted expression of DUO1 depends upon
positive promoter elements and not upon a proposed repressor
binding site.
Abstract Conclusion
Thus, DUO1 is a key regulator in the production of functional
sperm cells in flowering plants that has a novel integrative
role linking gametic cell specification and cell cycle
progression.
BBSRC:
The Biotechnology and Biological Sciences Research Council
(BBSRC) is the UK funding agency for research in the life
sciences. Sponsored by Government, BBSRC annually invests around
£420 million in a wide range of research that makes a
significant contribution to the quality of life for UK citizens
and supports a number of important industrial stakeholders
including the agriculture, food, chemical, healthcare and
pharmaceutical sectors. BBSRC carries out its mission by funding
internationally competitive research, providing training in the
biosciences, fostering opportunities for knowledge transfer and
innovation and promoting interaction with the public and other
stakeholders on issues of scientific interest in universities,
centres and institutes.
The Babraham Institute, Institute for Animal Health, Institute
of Food Research, John Innes Centre and Rothamsted Research are
Institutes of BBSRC. The Institutes conduct long-term,
mission-oriented research using specialist facilities. They have
strong interactions with industry, Government departments and
other end-users of their research.
For more information see:
http://www.bbsrc.ac.uk
ABOUT THE UNIVERSITY OF LEICESTER
A member of the 1994 Group of universities that share a
commitment to research excellence, high quality teaching and an
outstanding student experience.
Named University of the Year by Times Higher (2008) Shortlisted
(2006, 2005) and by the Sunday Times (2007)
Ranked second to Cambridge for student satisfaction amongst full
time students taught at mainstream universities in England
Ranked as a Top 20 university by the Sunday Times,
Guardian,Times and UK Complete University Guide, published in
The Independent
Ranked in world's top 200 universities by Shanghai Jiao Tong
International Index, 2005-08 and the Times Higher Education-QS
World University Rankings
Ranked top 10 in England for research impact by The Guardian
Students' Union of the Year award 2005, short listed 2006 and
2007
Founded in 1921, the University of Leicester has more than
20,000 students from 136 countries. Teaching in 18 subject areas
has been graded Excellent by the Quality Assurance Agency-
including 14 successive scores - a consistent run of success
matched by just one other UK University. Leicester is world
renowned for the invention of DNA Fingerprinting by Professor
Sir Alec Jeffreys and houses Europe's biggest academic Space
Research Centre. The latest Research Assessment Exercise
adjudged Leicester to have world leading research in every
subject panel and identified Museum Studies (at 65%) as having
the highest proportion of world leading researchers compared
with any other subject area at any university in the UK.
Leicester also emerged as having one of the highest proportions
of staff who are research active in the UK, with approximately
93% of staff submitted for the exercise. The University's
research grant income places it among the top 20 UK research
universities. The University employs over 3,000 people, has an
annual turnover of over £200m, covers an estate of 94 hectares
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