Breeding plants with genes from one parent
Advance could shorten times for crop breeding

Date:
November 19, 2021
Source:
University of California - Davis
Summary:
Scientists are a step closer to breeding plants with genes from
only one parent. New research led by plant biologists at UC Davis
shows the underlying mechanism behind eliminating half the genome
and could make for easier and more rapid breeding of crop plants
with desirable traits such as disease resistance.



FULL STORY ========================================================================== Scientists are a step closer to breeding plants with genes from only
one parent. New research led by plant biologists at the University
of California, Davis, published Nov. 19 inScience Advances, shows the underlying mechanism behind eliminating half the genome and could make
for easier and more rapid breeding of crop plants with desirable traits
such as disease resistance.


==========================================================================
The work stems from a discovery made over a decade ago by the late Simon
Chan, associate professor of plant biology in the UC Davis College of Biological Sciences, and colleagues.

Plants, like other sexual organisms, inherit a matching set of chromosomes
from each parent. In order to transmit a favorable trait, such as pest
or drought resistance, to all their offspring, the plant would have to
carry the same genetic variant on each chromosome. But creating plants
that "breed true" in this way can take generations of cross-breeding.

In 2010, Chan and postdoctoral fellow Ravi Maruthachalam serendipitously discovered a way to eliminate the genetic contribution from one parent
while breeding the lab plant Arabidopsis. They had modified a protein
called CENH3, found in the centromere, a structure in the center of a chromosome. When they tried to cross wildtype Arabidopsiswith plants
with modified CENH3, they got plants with half the normal number of chromosomes. The part of the genome from one parent plant had been
eliminated to create a haploid plant.

That work was published in Nature in March 2010, setting off efforts to
achieve the same result in crop plants such as maize, wheat and tomato.

Clearing up a mystery But replicating Chan's exact strategy outside
Arabidopsis has so far proved fruitless, said Professor Luca Comai,
UC Davis Department of Plant Biology and Genome Center, who is senior
author on the new paper. Recently, other labs have created plants with
one set of chromosomes by manipulating CENH3, but it's not clear how
the results are related.

"The mechanistic basis of CENH3 effects on haploid induction was
mysterious," Comai said. There appear to be different rules for each
species, he said.

Much of that mystery has now been cleared up. Mohan Marimuthu, researcher
at the UC Davis Genome Center and Department of Plant Biology, with
Comai, Maruthachalam (now at the Indian Institute of Science Education
and Research, Kerala) and colleagues found that when CENH3 protein is
altered, it is removed from the DNA in the egg before fertilization,
weakening the centromere.

"In the subsequent embryonic divisions, the CENH3-depleted centromeres contributed by the egg fail to compete with the CENH3-rich ones
contributed by the sperm and the female genome is eliminated," Comai said.

The finding that any selective depletion of CENH3 engenders centromere
weakness explains the original results by Chan and Maruthachalam as
well as new results from other labs in wheat and maize, Comai said. This
new knowledge should make it easier to induce haploids in crop plants,
he said.

Additional authors on the paper are: at UC Davis, Anne Britt and Sundaram Kuppu; Ramesh Bondada, Indian Institute of Science Education and Research;
and Ek Han Tan, University of Maine. The work was supported by grants
from CSIRO (Australia), Bill and Melinda Gates Foundation, Gordon and
Betty Moore Foundation, Howard Hughes Medical Institute, and the Indian Ministry of Education.

========================================================================== Story Source: Materials provided by
University_of_California_-_Davis. Original written by Andy Fell. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Mohan P. A. Marimuthu, Ravi Maruthachalam, Ramesh Bondada, Sundaram
Kuppu, Ek Han Tan, Anne Britt, Simon W. L. Chan, Luca Comai.

Epigenetically mismatched parental centromeres trigger genome
elimination in hybrids. Science Advances, 2021; 7 (47) DOI:
10.1126/sciadv.abk1151 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211119155448.htm

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