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Plant grafting: new mechanisms, evolutionary implications.

Goldschmidt EE - Front Plant Sci (2014)

Bottom Line: Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant.Grafting also has significant pathogenic projections.This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating that natural grafts may play a role in plant speciation, under certain circumstances.

View Article: PubMed Central - PubMed

Affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem Rehovot, Israel.

ABSTRACT
Grafting, an old plant propagation practice, is still widely used with fruit trees and in recent decades also with vegetables. Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant. However, the mechanisms underlying interspecific graft incompatibility are as yet insufficiently understood. Hormonal signals, auxin in particular, are believed to play an important role in the wound healing and vascular regeneration within the graft union zone. Incomplete and convoluted vascular connections impede the vital upward and downward whole plant transfer routes. Long-distance protein, mRNA and small RNA graft-transmissible signals currently emerge as novel mechanisms which regulate nutritional and developmental root/top relations and may play a pivotal role in grafting physiology. Grafting also has significant pathogenic projections. On one hand, stock to scion mechanical contact enables the spread of diseases, even without a complete graft union. But, on the other hand, grafting onto resistant rootstocks serves as a principal tool in the management of fruit tree plagues and vegetable soil-borne diseases. The 'graft hybrid' historic controversy has not yet been resolved. Recent evidence suggests that epigenetic modification of DNA-methylation patterns may account for certain graft-transformation phenomena. Root grafting is a wide spread natural phenomenon; both intraspecific and interspecific root grafts have been recorded. Root grafts have an evolutionary role in the survival of storm-hit forest stands as well as in the spread of devastating diseases. A more fundamental evolutionary role is hinted by recent findings that demonstrate plastid and nuclear genome transfer between distinct Nicotiana species in the graft union zone, within a tissue culture system. This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating that natural grafts may play a role in plant speciation, under certain circumstances.

No MeSH data available.


Related in: MedlinePlus

Mentor grafting. (A) Non-graft normal plant as control. (B) Mentor graft; scion leaves were removed in order to facilitate chromatin translocation from rootstock leaves and stems to the primordial organs of the scion. Arrows indicate the direction of chromatin translocation (reproduced from Ohta, 1991; with permission).
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Figure 2: Mentor grafting. (A) Non-graft normal plant as control. (B) Mentor graft; scion leaves were removed in order to facilitate chromatin translocation from rootstock leaves and stems to the primordial organs of the scion. Arrows indicate the direction of chromatin translocation (reproduced from Ohta, 1991; with permission).

Mentions: Of all grafting issues, the least understood and most controversial is the ‘graft hybrid’ concept. According to this concept grafting may involve stock to scion transfer of genetic material (= graft transformation), leading to heritable changes in the scion. The scion which has acquired certain heritable traits from the rootstock is regarded as a ‘graft hybrid.’ However, graft transformations occur only under ‘Mentor grafting’ conditions, which presumably enforce the transfer of genetic material from stock to scion (Figure 2).


Plant grafting: new mechanisms, evolutionary implications.

Goldschmidt EE - Front Plant Sci (2014)

Mentor grafting. (A) Non-graft normal plant as control. (B) Mentor graft; scion leaves were removed in order to facilitate chromatin translocation from rootstock leaves and stems to the primordial organs of the scion. Arrows indicate the direction of chromatin translocation (reproduced from Ohta, 1991; with permission).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269114&req=5

Figure 2: Mentor grafting. (A) Non-graft normal plant as control. (B) Mentor graft; scion leaves were removed in order to facilitate chromatin translocation from rootstock leaves and stems to the primordial organs of the scion. Arrows indicate the direction of chromatin translocation (reproduced from Ohta, 1991; with permission).
Mentions: Of all grafting issues, the least understood and most controversial is the ‘graft hybrid’ concept. According to this concept grafting may involve stock to scion transfer of genetic material (= graft transformation), leading to heritable changes in the scion. The scion which has acquired certain heritable traits from the rootstock is regarded as a ‘graft hybrid.’ However, graft transformations occur only under ‘Mentor grafting’ conditions, which presumably enforce the transfer of genetic material from stock to scion (Figure 2).

Bottom Line: Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant.Grafting also has significant pathogenic projections.This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating that natural grafts may play a role in plant speciation, under certain circumstances.

View Article: PubMed Central - PubMed

Affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem Rehovot, Israel.

ABSTRACT
Grafting, an old plant propagation practice, is still widely used with fruit trees and in recent decades also with vegetables. Taxonomic proximity is a general prerequisite for successful graft-take and long-term survival of the grafted, composite plant. However, the mechanisms underlying interspecific graft incompatibility are as yet insufficiently understood. Hormonal signals, auxin in particular, are believed to play an important role in the wound healing and vascular regeneration within the graft union zone. Incomplete and convoluted vascular connections impede the vital upward and downward whole plant transfer routes. Long-distance protein, mRNA and small RNA graft-transmissible signals currently emerge as novel mechanisms which regulate nutritional and developmental root/top relations and may play a pivotal role in grafting physiology. Grafting also has significant pathogenic projections. On one hand, stock to scion mechanical contact enables the spread of diseases, even without a complete graft union. But, on the other hand, grafting onto resistant rootstocks serves as a principal tool in the management of fruit tree plagues and vegetable soil-borne diseases. The 'graft hybrid' historic controversy has not yet been resolved. Recent evidence suggests that epigenetic modification of DNA-methylation patterns may account for certain graft-transformation phenomena. Root grafting is a wide spread natural phenomenon; both intraspecific and interspecific root grafts have been recorded. Root grafts have an evolutionary role in the survival of storm-hit forest stands as well as in the spread of devastating diseases. A more fundamental evolutionary role is hinted by recent findings that demonstrate plastid and nuclear genome transfer between distinct Nicotiana species in the graft union zone, within a tissue culture system. This has led to the formation of alloploid cells that, under laboratory conditions, gave rise to a novel, alloploid Nicotiana species, indicating that natural grafts may play a role in plant speciation, under certain circumstances.

No MeSH data available.


Related in: MedlinePlus