Physiological and Proteomic Investigations to Study the Response of Tomato Graft Unions under Temperature Stress.
BACKGROUND
Grafting is an established practice for asexual propagation in horticultural and agricultural crops. The study on graft unions has become of interest for horticulturists using proteomic and genomic techniques to observe transfer of genetic material and signal transduction pathways from root to shoot and shoot to root. Another reason to study the graft unions was potentially to observe resistance against abiotic stresses. Using physiological and proteomic analyses, we investigated graft unions (rootstock and scions) of tomato genotypes exposed to standard-normal (23/23 and 25/18°C day/night) and high-low temperatures (30/15°C day/night).


RESULTS
Graft unions had varied responses to the diverse temperatures. High-low temperature, but not standard-normal temperature, induced the production of reactive oxygen species (ROS) in the form of H2O2 and O2-1 in rootstock and scions. However, the expression of many cell protection molecules was also induced, including antioxidant enzymes and their immunoblots, which also show an increase in their activities such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The graft interfaces thus actively defend against stress by modifying their physiological and proteomic responses to establish a new cellular homeostasis. As a result, many proteins for cellular defense were regulated in graft unions under diverse temperature, in addition to the regulation of photosynthetic proteins, ion binding/transport proteins, and protein synthesis. Moreover, biomass, hardness, and vascular transport activity were evaluated to investigate the basic connectivity between rootstock and scions.


CONCLUSIONS
Our study provides physiological evidence of the grafted plants' response to diverse temperature. Most notably, our study provides novel insight into the mechanisms used to adapt the diverse temperature in graft unions (rootstock/scion).
Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju, 660-701, Korea.
Sowbiya
S
Muneer
Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju, 660-701, Korea.
Chung Ho
CH
Ko
Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju, 660-701, Korea.
Hao
H
Wei
Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju, 660-701, Korea.
Yuze
Y
Chen
Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju, 660-701, Korea.|Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, Korea.|Research Institute of Life Science, Gyeongsang National University, Jinju, 660-701, Korea.
Byoung Ryong
BR
Jeong
D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism; D060387:Ascorbate Peroxidases / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D006861:Hydrogen Peroxide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D058977:Molecular Sequence Annotation; D017440:Photoperiod; D010788:Photosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000378:metabolism; D058439:Plant Somatic Embryogenesis Techniques; D040901:Proteomics; D015398:Signal Transduction; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013696:Temperature
D000975:Antioxidants; D010940:Plant Proteins; D013481:Superoxides; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase