Cacti can become ''rock busters'' through symbiotic relationship with bacteria

Cacti can become ''rock busters'' through symbiotic relationship with bacteria

London, August 20 : Scientists have found that few plants like the cacti can grow on nothing but bare rockas the have evolved a symbiotic relationship with rock-dissolving bacteria, which they allow to grow in their roots.

According to a report by BBC News, Dr Yoav Bashan, a biologist at the Northwestern Center for Biological Research in La Paz, Mexico, and US-based colleagues Dr Esther Puente and Dr Ching Li discovered that cardon catus, growing in the volcanic region of the Baja California Sur mountain range, harbour bacteria that are capable of dissolving rock.

The cacti even incorporate these rock-busting bugs into their seeds, passing them on to future generations.

"We were working in the desert, when we observed that many individual cacti grew in sheer rocks," said Dr Yoav Bashan, a biologist at the Northwestern Center for Biological Research in La Paz, Mexico.

"They looked good and green in habitats where usually plants do not grow," he added.

The enigma, according to Dr Bashan, is that plants need minerals and nitrogen to survive. But neither are available from rock, which binds in minerals and contains no accessible nitrogen.

"The only explanation that we could think of is involvement of microorganisms assisting the plant to grow, fixing nitrogen and dissolving mineral," he said. "We looked for them and found them," he added.

These bacteria not only live on the surface of the plant''s roots, but also within cells that make up the root itself.

Further tests revealed the endophytic bacteria also grow in the cactus fruit and from there are transferred into seeds, and that these bacteria can weather rock, dissolving particles into smaller sizes.

"We believe that we have found a new symbiosis between bacteria and plants," said Dr Bashan.

"The cactus is the carbon provider for the bacteria and the bacteria indirectly provide the minerals and nitrogen for the plant," he added.

The bacteria and plant work in concert. The bacteria dissolve the rock, allowing the cactus seed to take purchase. The roots then drill into the weathered rock, fracturing it further.

"Consequently, below the plant is a small cave where the rocks were consumed and washed as soil and the roots are literally in the air," Dr Bashan explained.

Further tests revealed that without the bacteria, cacti couldn''t survive.

The relationship is especially fruitful because the cacti are able to pass the bacteria onto the next generation.

"When a seed falls in bats and bird droppings onto barren rock, it contains all the bacteria it needs to pioneer colonization of that rock," said Dr Bashan. (ANI)