Salinity tolerant rice shows promise

Bangladeshi scientists have developed four transgenic rice varieties capable of production in high soil salinity, far better than the ones now available in the market that were derived from conventional breeding.

A particular pea gene -- helicase -- was infused into four high yielding rice varieties (HYVs) that helped rice plants have higher salt tolerance and higher yield potential, scientists told The Daily Star.

They were readying two most promising varieties for trials in greenhouses.

In lab and net house, the transgenic varieties had shown potential to yield up to 50 percent more than the available salt-tolerant HYVs in saline-stressed soil.

In Bangladesh, one million hectares out of a total nine million hectares of cultivable land are salinity affected, and the vulnerability is more profound during the dry season. That's why the scientists chose the dry season Boro rice varieties first for the gene transfusion.

A team led by Dhaka University's Biochemistry and Molecular Biology Professor Zeba Islam Seraj made it possible after a decade of research.   

Agriculture Minister Matia Chowdhury yesterday called Zeba to congratulate her and her team for the breakthrough and promised support. 

A transgenic crop plant contains a gene or genes which have been artificially inserted.

The Zeba-led team applied multiple techniques of breeding that include genetic engineering, tissue culture and marker-assisted backcrossing.

Zeba first procured the pea gene from International Centre for Genetic Engineering and Biotechnology (ICGEB) and then using Agrobacterium as carrier infused the salt-tolerance vigour into home-grown rice variety Binnatoa.

The team of scientists who have developed four salinity-tolerant rice varieties. Photo: Collected

Later, her team crossed the helicase-infused Binnatoa with four HYVs, BRRI Dhan-28, BRRI Dhan-29, BRRI Dhan-36 and BRRI Dhan-47.

Agrobacterium is well known for its ability to transfer organism's genetic information between itself and plants, and for this reason it has become an important tool for genetic engineering.

All the four HYVs were developed by the Bangladesh Rice Research Institute (BRRI) and are known for their high yield potential. 

Zeba and her team are now concentrating on two transgenic rice varieties (derived from BRRI Dhan-28 and BRRI Dhan-47) as these two have been found to have the most potential.

Once the biosafety regulators give permission in a meeting scheduled later on this month, the two rice varieties would be put on confined trials inside BRRI's transgenic greenhouse and then on controlled field trials.

Zeba expects farmers to have the transgenic rice for cultivations in two to three years, provided the trials go well.  

Team member Md Sazzadur Rahman, senior scientific officer of BRRI, told The Daily Star that BRRI Dhan-47 was a salt tolerant HYV and could withstand up to 8 decisiemens per metre of salinity.

"If you grow BRRI Dhan-47 in non-saline condition, it has 7 tonnes of potential yield per hectare, but it will give you half the yield in 8 decisiemens per metre saline condition as after 4 decisiemens per metre threshold, yield continues to drop with rising salinity," he said, adding that the transgenic rice showed potential of providing up to 50 percent more yield in moderate saline conditions.

Zeba, who was instrumental behind the government's move to employ employing late Maqsudul Alam in jute genome sequencing, told The Daily Star, "There are salinity level up to 15/16 decisiemens per metre in coastal regions but even if we can cover 50 percent of the moderate salinity-prone farmland under transgenic rice, the country's rice productivity would have a significant boost."

The other core members of salt tolerant transgenic rice project team are Mahzabin Amin, Sudip Biswas, Tasnim Ahmed, Sabrina M Elias, and Narendra Tuteja. 

Bangladesh Council of Scientific and Industrial Research (BCSIR, popularly known as Science Laboratory) played a vital role in helping the scientists develop the rice.

"We've state-of-the-art real-time PCR [polymerase chain reaction] facilities in our Rajshahi centre and we let the team use that. It helped them know easily how the pea gene is expressed in the varieties they've infused it with," said M Rezaul Karim, a principal scientific officer of Bcsir. 

The PCR is a technology in molecular biology used to amplify a single copy or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.

Talking to this correspondent yesterday, Agriculture Minister Matia Chowdhury said better rice breeds that could withstand salinity would align well with the government's new policy of promoting Boro in the southern region and rain-fed Aman in the northern region.

"We just don't want to further deplete the groundwater level in the North by cultivating too much of irrigated-rice. So if we can grow more salt tolerant rice in the saline-prone South, we'll emphasise on growing more rain-fed Aman and Aus in the North."

She said government would arrange for more funding for pursuing biotechnology so that more stress-resistant varieties could be developed.