Cherifloema: Effect of ploidy and drought on phloem conductivity: application to fruit trees with high water requirements

Juan M. Losada holds a degree in Biology (2006) and in Food Science and Technology (2008) from the University of Vigo. He did his doctoral thesis (2012) with María Herrero in reproductive biology at Aula Dei Experimental Station – CSIC (Zaragoza), where he studied cell communication mechanisms during apple tree reproduction. During his post-doctoral stage at Harvard University (Arnold Arboretum, Boston, USA), he studied the evolution of reproductive structures in early diverging flowering plants in William E. Friedman’s laboratory and in gymnosperms with Andrew B. Leslie at Brown University (Providence, USA). This led to his interest in the mechanisms of long-distance nutrient transport in plants, so he joined the laboratory of N. Michele Holbrook at Harvard, where he explored the anatomy of phloem tubes in woody plants. Since September 2018 and until 2021, he was a ComFuturo researcher in the Institute of Subtropical and Mediterranean Horticulture “La Mayora” of the CSIC, in which he carried out his ComFuturo project “Effect of ploidy and drought on phloem conductance: application to fruit trees with high water requirements.“. After ComFuturo, he resulted beneficiary of a Ramón y Cajal position.

Project Summary

Plants, like animals, have a complex network of veins that are essential for their survival because they transport nutrients to their various growing organs, including fruit. Water is needed for this transport, so the scarcity of irrigation water greatly limits the fruit available for human consumption. This network of veins is called phloem and consists essentially of microscopic tubes that break easily when we touch them, so very little is known about how they work, especially when these tubes extend over long distances, as in the case of trees. In nature, plants are capable of doubling or tripling their number of chromosomes, generating polyploid individuals, whose resistance to water deficit or drought is unknown.

In this project, the researcher will be a fruit tree cardiologist to study how phloem veins vary in a fruit species with different chromosomal sets (diploid, triploid and tetraploid).

The research aim is to answer two questions: Is the size of nutrient-carrying veins increased in individuals with double or triple the number of chromosomes, and how does the chromosomal set affect plant resistance to drought?

The answer to these questions would constitute an important advance in our knowledge of how plant genetics influences its anatomy, providing it with greater or lesser resistance to drought.

With this information, it is possible to generate general models of nutrient and water transport in plants that can be used by producers, breeders and land managers to search for food varieties that need less irrigation or to ensure food for future generations using fewer resources, in a situation of climate change that is leading us towards drier ecosystems.

Application: Climate change predictions foresee a near future with much less water available for irrigation, as primary production of plant-based foods will be limited. This research project focuses on finding out how fruit trees could produce fruit using less irrigation water. An in-depth understanding of the effects of drought on fruit trees with different genetic identities would be an important breakthrough on how plant genetics influence their anatomy, making them more or less resistant to drought. With this information, it would be possible to produce fruit trees that are more resistant to drought, or graft rootstocks that use water more efficiently.

Scientific output derived from the ComFuturo Cherifloema Project

Scientific articles

J. M. Losada; Z. He; N.M. Holbrook (2021). Sieve tube structural variation from leaves to stems in Austrobaileya scandens and its significance for lianescence. BIOARXIVES. DOI: 10.1101/2021.09.23.461614


M. Barceló-Anguiano; N.M. Holbrook; J.I. Hormaza; J.M. Losada (2021). Changes in ploidy affect vascular allometry and hydraulic function in Mangifera indica trees. THE PLANT JOURNAL 108: 541-554. DOI: 10.1111/tpj.15460


M. Barceló-Anguiano; J.I. Hormaza; J.M. Losada (2021). Conductivity of the phloem in Mangifera indica L. HORTICULTURE RESEARCH 8, 150. DOI: 10.1038/s41438-021-00584-1


J. M. Losada; M. Díaz; N.M. Holbrook (2020). Idioblasts and peltate hairs as distribution networks for water absorbed by xerophilous leaves. PLANT CELL AND ENVIRONMENT 44:1346–1360. DOI: 10.1111/pce.13985


J. M Losada; N.M. Holbrook (2019). Scaling of phloem hydraulic resistance in stems and leaves of Illicium parviflorum, an understory tropical shrub. AMERICAN JOURNAL OF BOTANY. DOI:10.1002/ajb2.1241


Works presented at conferences

J. M. Losada. Anatomía del xilema y floema en frutales subtropicales relacionado a la mejora del uso del agua. Universidad Central de Ecuador. Invited oral presentation. Quito, Ecuador. 6/08/2021


A. Montano-García; J. Lora; J. I. Hormaza; J. M. Losada. Cell morphology and vascular differentiation in the meristems of diploid, triploid and tetraploid Annona cherimola genotypes. Botany 2021 Virtual. Oral presentation. 18/07/2021-23/07/2021


J. M. Losada. Frutales subtropicales poliploides y la mejora del uso del agua. Estación Experimental de Aula Dei-CSIC. Invited oral presentation. 9/07/2021


J. M. Losada. Transporte hidráulico en plantas leñosas de diferente ploidía: estudios de caso en frutales subtropicales. Instituto de las Ciencias de la Vid y el Vino-CSIC. Invited oral presentation. 8/02/2021


J. M. Losada. From individual cells to organisms: source to sink transport in subtropical fruit trees with different ploidies. Universidad de Arizona, USA. Invited oral presentation. 26/10/2020


M. Barceló-Anguiano; J.I. Hormaza; J.M. Losada. Source-sink transport in polyploid trees: a case example in autotetraploid mango (Mangifera indica). Congreso de la Botanical Society of America virtual. Oral presentation.  27/07/2020-31/07/2020


J. M. Losada. Phloem anatomy in woody plants with different ploidies. Freie Universitat Berlin, Germany. Invited oral presentation. 6/12/2019


M. Barceló-Anguiano; J.M Losada. Efecto de la ploidía en la anatomía del floema del mango. Congreso de jóvenes investigadores en ciencias agroalimentarias. Poster. Almería, Spain. 17/10/2019


M. Barceló-Anguiano; J.M Losada. The effect of ploidy on phloem structure in woody plants. XVIII Congreso Sociedad Española de Biología Celular. Oral presentation. Badajoz, Spain. 15/10/2019-18/10/2019


J. M Losada; J. Lora; L. Alcaraz; J.I Hormaza. Bringing light onto hidden complex interactions: microscopy as a tool to study sexual reproduction in trees. Microscopy at the Frontiers of Science. Invited oral presentation. Granada, Spain. 11/09/2019-13/09/2019


M. Barceló-Anguiano; J.M Losada. Efecto de la ploidía en la anatomía del floema del mango: implicaciones fisiológicas. I Simposio de estudiantes IHSM-La Mayora. Oral presentation. Málaga, Spain. 10/09/2019


J. M. Losada. Conductivity of the phloem in woody systems: perspectives for water use efficiency in fruit crops. MERC program. Invited oral presentation. Málaga, Spain. 3/11/2018