Three young scientists research post-harvest deterioration of cassava

The fact that post-harvest physiological deterioration (PPD) is one of the most significant bottlenecks in cassava processing chains may be nothing new, as it is one of the biggest challenges facing cassava producers, but that three young scientists have keen interest in a long-term effort to tackle this challenge proves quite encouraging.

Luis Augusto Becerra, molecular biologist at CIAT’s Cassava Program, shares that perception: “The questions they ask, their eagerness to learn more and more about the subject, the discussions, all this makes it a daily motivation.”

“It’s not only about more productive varieties, but also varieties that can last longer when stored.”

Virgilio Uarrota keeps in mind the situation that cassava growers live in his homeland Mozambique. There, farmers have to travel across long distances from their farms to the market places where they sell the roots.

It is precisely that reality that motivates him to research for a model that can make possible to quantify and assess post-harvest deterioration and understand the involved compounds through a study of metabolomic and enzymatic variability during physiological deterioration, with the intent to team with breeders, in a not too far future, to develop varieties that can be stored at least for a week without losing their starch content, thus contributing to opening more opportunities for farmers to sell their roots at good prices.

The research for creating this model is the subject of his PhD thesis in Plant Genetic Resources at Federal University of Santa Catarina in Brazil. His thesis work is supported by a TWAS fellowship, for advanced research and training, which he received through an NGO in his home country with collaboration from UNESCO.

Being able to carry out that research has meant for Virgilio a very valuable opportunity to take advantage of CIAT’s biotechnology platform. “Now I know how to extract DNA and RNA,” he said while vivaciously describing the way how, during his research, he used tools such as Ultraviolet Visible Near- Infrared spectrometry (UV-Vis-NIR), Fourier Transform Infrared Spectroscopy (FT-IR), High-Performance Liquid Chromatography (HPLC), and many others.

Virgilio is just a few days away from returning to Federal University of Santa Catarina in Brazil, where he hopes to be able to keep in touch with cassava researchers and to inspire other young scientists to work in the topic of post-harvest deterioration.

It is a topic that seems to be researched by very few groups. Virgilio, however, is determined to keep putting his talent to use to unveil the secrets of post-harvest deterioration from a research center through which he can exchange information with CIAT on a regular basis.

What has been written on post-harvest deterioration?

“The topic of epiphytic microorganisms as the causal agent of primary post-harvest deterioration seems to have been postponed indefinitely” said Carolina Ospina, Biology student at Los Andes University, Colombia, after reviewing scientific literature published on the subject of post-harvest deterioration from 1955 through 2012.

While this ample literature review is the monograph that she will present in August to apply for the BSc degree in biology, the most relevant part for Carolina is the process of unvarying motivation that she has experienced during this time.

“It was like spilling my head off,” that is how she describes how with each article, each recommendation, each discussion, cassava breeders would motivate her on this path of learning to find the various theories, trends, and research lines related to this crucial topic.

Carolina has not yet decided on which line of biology or microbiology she will specialize, but so far post-harvest deterioration seems to be a particularly tempting challenge.

“Researching post-harvest deterioration is a very big challenge”

That is how Jorge Luna, agro-industrial engineer, senses the challenge of discovering the enzyme(s) or endogenous or exogenous actors that cause post-harvest deterioration of cassava. He believes that the key might be in Scopoletin, a hydroxycoumarin that appears in different proportions in roots and seems to be closely related to deterioration; however, what exactly starts that molecule production is still unknown.

The first time that Jorge came to CIAT, as an intern student, was from April to October 2010, to work on carotenoid quantification in yellow roots. During that time, he also had the chance to run some tests on post-harvest deterioration. Ever since, and despite having found a job opportunity at National University of Colombia-Palmira campus, he remained intrigued by the subject.

Today, Jorge is a masters student in Genetic Improvement at National University of Colombia. And he did not think twice to return to CIAT and conduct his thesis work, which focuses on assessing two families of cassava genotypes and observing their behavior towards post-harvest physiological deterioration after 7 days in storage conditions.

So far he has observed some results that keep him increasingly intrigued: in some genotypes it seems that the more dry matter content is in the root, the faster root rot occurs. But this is not a standard and in some roots of the same plant, this process occurs at ‘a different rate.’ For example, the lower the level of carotenes, the faster deterioration occurs.

Jorge has included in his research other variables related to post-harvest deterioration, such as plant physiological age and cyanide content; all this with the intent to significantly contribute to tackling this challenge that affects farmers, because as he says “I grew up as a farmer, with my hands in the dirt.”

Luis Augusto Becerra concludes that “each one of these young scientists brings a new, fresh view, plentiful of the vigor of youth that takes nothing for granted and questions with hunger for discovering more and more.”

Source: Original blogpost by Andrea Carvajal on CIAT website.