Research reveals cultivation of plants with genes from one parent

According to a study led by the plant biologists at the University of California, scientists are a step closer to breeding plants with genes from only one parent. Their findings have shown the underlying mechanism and could lead to easier as well as rapid breeding of crops. Apart from that, these crops will be having desirable traits such as disease resistance.

The research has been published in the 'Science Advances Journal'.

The work stemmed 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 favourable 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 centre of a chromosome. When they tried to cross wild type Arabidopsis with 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.

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," Comai added.

Much of that mystery has now been cleared up. Mohan Marimuthu, a 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 engendered centromere weakness explained 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.

( With inputs from ANI )

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