Advancements in genetic diversity assessment and tissue culture protocol optimisation for the conservation and improvement of local banana germplasm: A systematic review
This systematic review synthesizes evidence from 70 studies to demonstrate that effective conservation and improvement of local banana germplasm require integrating molecular diversity assessment with genotype-specific tissue culture optimization, while highlighting critical gaps in research on recalcitrant African landraces and the need for standardized protocols and capacity building.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Bananas are far more than a convenient snack; for millions of people across the tropics, they are a daily staple, a critical source of nutrition, and a lifeline for family incomes. Yet, this vital crop faces a constant barrage of threats. Diseases like Fusarium wilt and bacterial blight can wipe out entire fields, while climate stresses like drought weaken the plants' ability to survive. To protect these crops, scientists rely on a dual strategy: understanding the unique genetic makeup of different banana varieties and using laboratory techniques to grow them quickly and cleanly. The genetic makeup, or diversity, of a banana plant determines how it reacts to disease and stress, while tissue culture is the method of growing new plants from tiny pieces of tissue in a sterile jar, bypassing the slow and disease-prone method of using suckers from the ground. The challenge lies in the fact that not all bananas respond the same way to these high-tech methods; some varieties thrive in the lab, while others refuse to grow or change their genetic identity in the process.
A team of researchers set out to map the current state of this work, reviewing seventy scientific studies published between 2011 and 2026 to see how well scientists are managing to preserve and improve local banana varieties. They looked for patterns in how researchers identify the unique DNA of these plants and how they optimize the recipes used to grow them in the lab. The review reveals a clear picture of progress and persistent hurdles. The most common tool for reading the genetic code of local bananas is a technique called Simple Sequence Repeat markers, which act like a genetic fingerprint to distinguish one variety from another. While older methods are still used, there is a noticeable shift toward more advanced, high-speed genomic tools that can read the entire genetic code with greater precision. This shift is crucial because it allows scientists to spot subtle differences between plants that look identical to the naked eye, ensuring that the unique traits of local landraces are not lost during conservation efforts.
When it comes to growing these plants in the lab, the researchers found that the most successful approach involves taking the very tip of a shoot and placing it in a nutrient-rich liquid. The standard recipe for this liquid, known as Murashige and Skoog medium, works best when mixed with specific growth hormones. The most effective combination for multiplying the shoots involves a hormone called BAP at a concentration of two to five milligrams per liter, followed by a rooting phase using a different hormone, IBA, at half to two milligrams per liter. This method has been refined enough to produce disease-free plants with high survival rates, but it is not a one-size-fits-all solution. The success of the entire process depends heavily on the specific genetic background of the banana variety being grown.
The review highlights a significant divide in how different bananas respond to these laboratory conditions. Triploid varieties, which have three sets of chromosomes and include many common commercial types, generally grow well and multiply quickly in the lab. In contrast, many local landraces and diploid varieties, which have only two sets of chromosomes, are much more difficult to grow. These harder-to-grow plants often suffer from browning of their tissues, a reaction to stress that kills the cells, and they struggle to adapt when moved from the lab to the field. This genetic resistance, or recalcitrance, means that a protocol that works perfectly for one type of banana might fail completely for another. Furthermore, the study warns that growing plants through a callus stage—a mass of undifferentiated cells—rather than directly from a shoot tip increases the risk that the new plants will develop unwanted genetic changes, known as somaclonal variation, which can alter their desirable traits.
Despite the technical successes, the researchers identified major barriers that prevent these methods from being used everywhere. Microbial contamination, where bacteria or fungi invade the sterile jars, remains the single biggest obstacle, affecting nearly half of the studies reviewed. Phenolic oxidation, the browning of plant tissue, is the second most common problem. These issues are compounded by a lack of resources in many developing nations, where the laboratories needed to perform this work are scarce or underfunded. The geographic distribution of the research also shows a stark imbalance: the vast majority of studies come from Asia, particularly India, while Africa, a region where bananas are a critical food security crop, is significantly underrepresented in the scientific literature. This gap suggests that the protocols developed in Asia may not work for the unique African varieties that need them most.
Ultimately, the review concludes that saving and improving local banana germplasm requires a tight integration of genetic analysis and tissue culture. Scientists cannot simply apply a standard recipe; they must first understand the genetic identity of the plant to predict how it will behave in the lab. The most promising path forward involves tailoring the growth conditions to the specific needs of each variety, using molecular tools to verify that the new plants are true copies of the original, and investing heavily in building laboratory capacity in regions that need it most. The rapid increase in research output in recent years offers hope that these challenges are being addressed, but bridging the gap between high-tech solutions and the local farmers who rely on these crops remains an urgent task.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.