Apomixis: CCMB makes headway with clonal reproduction in Arabidopsis thaliana

Syed Akbar

Hyderabad:  The city-based Centre for Cellular and Molecular Biology has successfully explored the possibility of producing hybrid seeds through "clonal reproduction".

Unlike normal hybrid seeds, which lose their hybrid vigour in successive generations forcing farmers to purchase hybrid seeds from multinational companies year after year, seeds obtained through clonal reproduction continue to give higher yields. Farmers need not purchase hybrid seeds every year, they can simply select the seeds from their produce and sow them for better yields.

The CCMB's new technology will also bring down the present long gap in transferring new hybrid seed varieties to farmers. The existing technology takes at least 10 years for agricultural scientists to stabilise the hybrid vigour before passing on the seeds to farmers. However, the new technology will help in immediate transfer of hybrid seeds, reducing the 10 years gap between lab findings and field transfers.

According to Dr Ch Mohan Rao, director of CCMB, the new finding, when made applicable to food crops, will reduce the cost of hybrid seed production. "Farmers will be able to multiply their own hybrid seed and not be compelled to buy hybrid seeds for every planting," he said.

The research was carried by a team led by CCMB's scientist Dr Imran Siddiqi through an international collaboration. "Apomixis or clonal reproduction will greatly accelerate plant breeding because traits and combinations could be fixed as soon as they are observed instead of requiring many generations of breeding as is presently done," Dr Imran said, adding that apomixis technology has the potential to revolutionise agriculture in developing countries.

Dr Siddiqi's laboratory in CCMB experimented on Arabidopsis thaliana, a member of the mustard family. Efforts are now on to translate the results obtained from Arabidopsis on food grains like wheat and rice. "This is a key finding because it shows for the first time that the equivalent of apomixes can be achieved by manipulating known genes that function during normal sexual reproduction and cell division," Dr Mohan Rao said.

Stating that cloning through seeds has potential revolutionary applications in agriculture, Dr Mohan Rao said it would allow vigorous hybrids to be propagated indefinitely. However, asexual seed formation or apomixis, avoiding meiosis and fertilisation, is not found in the major food crops.

"To develop de novo synthesis of apomixis, we crossed Arabidopsis MiMe and dyad mutants that produce diploid clonal gametes to a strain whose chromosomes are engineered to be eliminated after fertilisation. Up to 34 per cent of the progeny were clones of their parent, demonstrating the conversion of clonal female or male gametes into seeds. We also show that first-generation cloned plants can be cloned again. Clonal reproduction through seeds can therefore be achieved in a sexual plant by manipulating two to four conserved genes," Dr Siddiqi observed