Bamboo is economically important for over one-third of the global population, and is one of the fastest growing subfamilies of plants in the world. But why does bamboo grow so fast? And why don’t we have an answer, despite knowing about bamboo’s rapid growth for over 1000 years?
While this question seems like it should be straightforward to answer, it isn’t. The difficulty lies in finding slower-growing mutants of bamboo to compare with regular, fast-growing bamboo. Such a comparison is needed to parse out what cellular and molecular mechanisms are responsible for speedy growth. In a recent article in Tree Physiology, Qiang Wei and colleagues took the first steps to figuring out why bamboo can grow so fast.
Using a slow- and fast-growing variant of bamboo, Wei and colleagues looked at cell division, growth, and gene expression (through transcriptomics, which measures all the genes being expressed by an individual) to discover which genes may be responsible for fast growth in bamboo. They found that the slow-growing variant had reduced expression of genes relating to cell wall construction, the plant hormone auxin (important for cell growth and cell division), and had irregular cell growth and cell walls. Wei and colleagues suggest that a reduced ability to produce and perceive auxin, combined with a weakened cell wall, are responsible for the slow growth seen in the bamboo variant.
So what does this mean for the fast growth of regular bamboo? Given the disruption of cell wall construction and auxin signalling in the slow-growing bamboo, the fast growth in bamboo may be possible due to a high level of coordination between cell division, cell growth, and cell wall biosynthesis, optimized for rapid growth. Further studies on bamboo could provide insight into the mechanisms required for engineering rapid growth into other plant species for use in agriculture and forestry.
See also A transcriptomic view of bamboo from a ‘mutant’ perspective at RNA-Seq blog