A collaborative research group has succeeded in identifying an important transcription factor, GCAM1, which allows liverwort plants to asexually reproduce through creating clonal progenies. Furthermore, this transcription factor was revealed to have the same origin as those which regulate secondary bud formation in angiosperms.
Most plants have plenty of enemies, from insects and other grazing creatures to various diseases, droughts and many other stressors.
Plants respond to injuries or illnesses by initiating various defense measures. But a viral infection requires a completely different response than desiccation, of course.
To know more about its attacker, the cell relies on mechanical and chemical signals.
Almond and the peach are two well-known tree species, since humans have been eating their fruit (peach) or seed (almond) for thousands of years. New research shows that the movement of the transposons could lie at the origin of the differences between the fruit of both species or the flavour of the almond.
Passion fruit woodiness caused by cowpea aphid-borne mosaic virus (CABMV), the disease that most affects passion fruit (Passiflora edulis) grown in Brazil, can be combated with a relatively simple technique.
A study published in the journal Plant Pathology shows that systematic eradication of plants with symptoms of the disease preserves the crop as a whole and keeps plants producing for at least 25 months.
The technique currently used to combat CABMV entails renewing the entire orchard every year. This is, of course, a costly procedure. According to the authors of the study, economic factors are critical for this crop, which is mostly grown by small producers.
CABMV occurs in all states of Brazil and impairs plant development. Passion fruit woodiness disease causes leaf mosaic, blisters, deformation and reduced fruit size, making the produce unmarketable. Vines are typically eliminated only when the disease is detected in the early stages of their life cycle. The researchers propose systematic roguing – removal of weak, diseased or abnormal plants – throughout the life of the crop.
The study was funded by FAPESP and CAPES, the Brazilian Ministry of Education’s Coordination for the Improvement of Higher Education Personnel. It was conducted by Brazilian researchers affiliated with the University of São Paulo’s Luiz de Queiroz College of Agriculture (ESALQ-USP), the Federal University of São Carlos (UFSCar) at Araras, the University of Southwest Bahia (UESB), and the Semiarid Agriculture Unit of the Brazilian Agricultural Research Corporation (EMBRAPA), as well as colleagues at Argentina’s National Agricultural Technology Institute (INTA).
“Roguing is a technique that has been used to combat papaya disease in Espírito Santo state since the 1980s. After several experiments, it was found to be the best way to control papaya ringspot virus type P [PRSV-P],” said Jorge Alberto Marques Rezende, Full Professor at ESALQ-USP and principal investigator for the study, which began in 2010.
CABMV is transmitted by aphid saliva and spreads throughout an orchard in a few months. The aphid species in question do not colonize the plants but merely visit them, and insecticide is not effective for control purposes.
“Insecticide affects their nervous system but takes hours to kill them. Meanwhile, they’re stimulated to feed on more plants, spreading the virus farther, so insecticide helps propagate the disease instead of controlling it,” said David Marques de Almeida Spadotti, first author of the article. The research was part of Spadotti’s postdoctoral fellowship at ESALQ-USP.
In previous experiments, the use of transgenic passion fruit plants and inoculation with attenuated variants of CABMV as a kind of vaccine also failed to control the disease. In this new study, an experimental orchard was planted in three areas belonging to ESALQ-USP in Piracicaba, São Paulo state, and two areas in Vitória da Conquista, southwestern Bahia. The experiments took place between 2013 and 2018. Approximately 100 healthy seedlings were planted in two areas of each city using trellises or T-shaped arbors connected by wires.
The vines were trained on the trellises and arbors for support but also to separate them so that the disease could easily be observed. Any buds with symptoms were identified and removed in weekly inspections.
In two other areas distant from the others, the same number of vines were planted using trellises and allowed to interlace without roguing, as in commercial plantations. The results of the two strategies were then compared.
In the absence of roguing, the virus spread throughout the crop in 120 days. In the areas submitted to systematic roguing, 8% of the vines were infected and removed after 180 days. In Piracicaba, only 16% had to be removed after 25 months, and the plants remained productive throughout this period.
The presence of CABMV in all infected or preventively removed vines was confirmed by PTA-ELISA serological testing.
“The symptoms appear eight days after inoculation of the virus on average. Roguing enables the grower to identify diseased plants visually and base control on visual inspection. Inspection should ideally be carried out at least once a week”Spadotti said.
According to the researchers, the next step in the study entails larger pilot plantings of 1,000-2,000 passion fruit vines. In addition to eradicating diseased plants, they plan to replace them with healthy plants. The idea is to maintain the orchard for three to four years and compare it with another orchard maintained in the conventional manner, in which all plants are replaced every year.
“Because passion fruit is semiperennial, this longer production period is more advantageous from an economic standpoint than complete annual substitution,” said Rezende, principal investigator for the Thematic Project “Begomovirus and Crinivirus in Solanaceae”, which also relates to viruses in food crops.
The researchers stress, however, that if the strategy is to succeed, it should be implemented by all passion fruit growers in any given region. In addition to other plantations, the virus can spread from old or abandoned orchards, which should be eliminated.
CABMV-susceptible wild species of passion fruit in forests near plantations may also spread the disease. One of the experimental areas in Vitória da Conquista failed for this reason. When the wild plants were eliminated, the incidence of CABMV was considerably reduced.
According to IBGE, the national statistics and census bureau, Brazil is the world’s leading grower of passion fruit, with more than 550,000 metric tons produced in 2017.
Read the paper: Plant Pathology
Article source: Agência FAPESP
Author: André Julião
Image: Jorge Rezende
This week we spoke with Professor Edith Taleisnik about her new book, ‘…¡y nos fuimos por las ramas!’ (‘we went along the branches’), an in-depth look at the history of plant physiology research in Argentina. (Edith previously described the activities and vision of the Argentinean Society of Plant Physiology (SAFV) on the blog – read it here).
Edith, you have put a huge amount of work into uncovering the history of plant physiology research in Argentina. Why did you decide to do it and how did you undertake this challenge?
The information was scattered, so the first thing we did was try to collect as many SAFV conference books as possible. Sending requests through the SAFV mailing did not work, so it was essentially through personal contacts that we were able to put together the whole collection of conference books. It is now deposited in the library of CIAP (Centro de Investigaciones Agropecuarias – contact: email@example.com). People also sent the minutes of past meetings and pictures.
Initially we were only going to analyze the conference books and interview some plant scientists that were among the first disciples of the “founding fathers” of Argentinian experimental plant biology, but as we worked, our book grew and diversified.
What was the most interesting thing you discovered while writing the book?
It’s hard to narrow down which discovery was most exciting!
Victorio Trippi, one of the disciples of the “founding fathers”, told us that many researchers initially published in the journal Phyton, which was founded in Argentina in 1951. Our inspection of the archives of this publication yielded a lot of valuable information, and was an enlightening experience. We traced great names in Argentine plant science to the very beginning of their careers, looking at their topics of interest, how they moved from one job to another, and who their co-authors were. Even earlier than this though, we managed to trace the first mention of plant hormones in Argentina to a paper written by Guillermo Covas in 1939.
Writing the book was rewarding too, because we realized that plant physiology research has steadily grown in Argentina, judging by the participation in the conferences and the amount of research groups all over the country. It was very good to reveal the significant contributions that Argentine experimental plant science has made to many topics, such as photobiology, crop ecophysiology, germination physiology, senescence, mineral nutrition and carbohydrate metabolism, among others.
Why did you decide to include essays from the many groups researching plant physiology in Argentina?
We included them to reflect how much plant physiology has grown and diversified in Argentina. In the book we also invite those that did not have a chance to join this edition to contribute to a future one.
What words of wisdom did the researchers who were interviewed want to share with early career researchers for the future?
Most of them emphasized the need for team work, with people from different background joining forces to tackle a specific problem. The SAFV, they point out, has provided a friendly environment that has promoted collaboration and exchange of ideas among its members, and they hope this spirit will persist. They are moderately optimistic about the future, underscoring the need for new research paradigms both in the public and private sectors.
Carlos Ballaré underscored the human aspect of the history of the SAFV in his description of your book, printed on the cover. Could you elaborate on this?
Carlos meant that the book includes personal accounts from the people that have devoted their professional lives to plant physiology and ecophysiology, anecdotes of how the research groups developed and grew, and tales of how researchers replaced the lack of equipment with clever ideas. He highlights that the book has an emphasis on human endeavor, rather than being just a review of numbers, places, and dates.
Beyond the analysis of numbers and growth, the book reveals how early researchers worked on problems that largely sprang from their environment, attempting to understand the causes of issues that had an impact on crop productivity. Thus, those in Tucumán initially worked on sugar cane, those in Mendoza researched grapevines, and the focus in Buenos Aires was potatoes. As groups grew and diversified, this initial link was often blurred; young researchers joining ongoing work never realized what the initial question had been.
In a country where agricultural products or their derivatives still make a significant contribution to GDP, it is sensible to resume the link to local agricultural problems. For this task, it will be essential to adopt a systemic collaborative approach.
To find out more about the book, read our recent news article here.
The book was edited by the SAFV . Printed copies can be purchased by request – please write to Lilian Ayala.
This week Professor Edith Taleisnik describes the vision and activities of the Argentinean Society of Plant Physiology (SAFV), a Member Organization of the Global Plant Council dedicated to promoting collaboration in plant science within Argentina, across Latin America and beyond.
The Argentinean Society of Plant Physiology (Sociedad Argentina de Fisiologia Vegetal; SAFV) was founded in 1958 to nucleate researchers and teachers in plant physiology in Argentina. Since then the SAFV has maintained continuous activity in the country and the region, providing opportunities for the dissemination and exchange of information related to plant function. It has about 350 members, mostly from Argentina and also from neighboring Uruguay. The SAFV is linked with the Global Plant Council and many other important international plant science organizations.
Exchanging ideas in Argentina and beyond
One of the main objectives of the society is to organize meetings, which are held every two years. The last one was held in Mar del Plata, and was attended by nearly 600 people. The SAFV has close ties with the Brazilian Society of Plant Physiology (BSPP), so every other SAFV meeting is a joint Latin American event in association with the BSPP. These meetings provide a unique opportunity for scientists in the area to meet, analyze and exchange views on the future of this field, to plan for joint efforts and enterprises, to share personal experiences and contribute to a regional and global perspective of local endeavors.
The participation of students and young scientists in SAFV meetings is stimulated by invitations to deliver lectures and organize symposia, and by making available fellowships that cover travel and registration costs. In accordance with its mandate to promote and diffuse knowledge in plant science, the SAFV also organizes and sponsors courses and workshops.
Plant science, and plant physiology in particular, has experienced steady growth and development in Argentina, reflecting the importance of agriculture in its broadest sense; pastures and forests for the Argentine economy. Established groups all over the country produce novel data on various aspects of plant function and interaction with other organisms and the environment, which is particularly relevant to local and global crop production. The wide range of this work is reflected in the proceedings of the last plant physiology meeting.
Other Argentinian plant science societies
There are several other plant science societies in Argentina. Scientists working on botanical and morphological topics are affiliated to the Sociedad Argentina de Botánica (SAB). The focus of the members of the Asociación Argentina de Ecología (AsAE) is centered in environmental topics. A more recently formed society, the Asociación Argentina de Fitopatólgos (AAF), is dedicated to plant pathology, while the Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB) features a section specifically devoted to plant biochemistry and molecular biology. All of these societies hold periodical meetings, stimulate the work of young scientists through incentives and prizes, and publish journals (e.g. Ecología Austral) and books.
Get in touch
About the author
Professor Edith Taleisnik researches the physiology of plants under saline stress for the Argentinean National Scientific and Technical Research Council (CONICET), and is based at the Instituto de Fisiologia y Recursos Geneticos Vegetales (IFRGV) CIAP, INTA, Argentina. Edith was the president of the SAFV from 2000 to 2004, and is now a member of the scientific committee.