Contributions to the Boyce Thompson Institute 16: 221-224 (1951)
ROSE "SPORTS" FROM ADVENTITIOUS BUDS
P. W. Zimmerman and A. E. Hitchcock

Many horticultural varieties of plants are multiplied by vegetative means to avoid genetic variation which often occurs when such species are propagated from seed. Plants derived from normal buds on the stem are like the parent type though occasional abnormal branches arise. These bud "sports" are due to somatic mutations or other variations in the bud. Roses frequently produce bud sports, and these have been of considerable importance in the selection of new varieties. They retain their desirable qualities when subsequently propagated from stem cuttings. New plants derived from root cuttings or adventitious buds on the stem, however, often differ from the parent type. Since adventitious buds on root cuttings are of endogenous origin, it is obvious that the genetic constitution of the internal core (stele) differs from the outer layer which on the stem produces normal buds. It appears, therefore, that new varieties which arise from bud sports are periclinal chimaeras with different genetic constitutions in the different tissues (stele and cortex).

This report involves new varieties of roses arising from adventitious buds on stems and roots and a bud sport of a commercial rose (Rosa sp., var. Briarcliff) called to the writers' attention about 1940 by Henry Kirkpatrick, Jr., of this laboratory.

RESULTS AND DISCUSSION

A bud sport appeared on a branch of a Briarcliff hybrid tea rose growing in a greenhouse. One branch differed from the rest of the plant in both leaf and flower characteristics. Briarcliff has a double pink flower and serrate leaves typical of the rose. The sport branch had nearly single pink flowers with crinkled petals and narrow, non-serrate leaves (Fig. 1). When the sport was propagated from stem cuttings, the new plants were like the original sport branch. When, however, the plants were propagated from adventitious buds arising on root cuttings, the new plants had leaves and flowers resembling Briarcliff variety. Also suckers from underground parts of the stem (presumably adventitious buds on internodes) reverted to Briarcliff type.

In attempting to determine the reasons for reversion to the original parent stock, it was assumed that the sport was a periclinal chimaera resulting from unusual somatic segregation in the bud. The inner core appeared to be Briarcliff while the outer layer was a new mixture of cells. This assumption is strengthened somewhat by the fact that three generations of root cuttings have continued to produce plants like Briarcliff. All plants from root cuttings (a total of 55) of the sport variety were like the Briarcliff strain. Ten plants, all like Briarcliff, have come from root cuttings of the first reversions. From the latter have come five new plants like Briarcliff, by way of root cuttings. It appears, therefore, that a pure line Briarcliff strain which continues to produce the same variety regardless of the method of propagation can be developed. Stem cuttings have never failed to come true to type.

Three other varieties of hybrid tea rose, Better Times, Souvenir, and one garden type (name unknown), did not come true when propagated from root cuttings.

FIGURE 1. Leaves of a bud sport of Briarcliff rose (left) and leaves of a plant which was made from a root cutting of the sport.

Better Times (Plant Patent 23), a hybrid type selected in 1934 as a bud sport from Briarcliff by J. H. Hill Company, has deep red flowers. It came true to type when propagated from stem cuttings, but when grown from root cuttings the flowers resembled Briarcliff. In one lot of twenty root cuttings one new plant was a climbing rose, resembling neither Briarcliff nor Better Times. This exception militates to some extent against the simple explanation that the adventitious buds from which the new plants developed, arose in the core of a periclinal chimaera and that these resembled only one of the parents.

The climbing rose varied from the parent plant in leaf, thorn, and flower characteristics and habit of growth. It did not bloom continouusly as a hybrid tea rose but resembled the average climbing rose which flowers annually. Clusters of flowers appeared on the terminal part of the main shoots. The buds along the stem became dormant and the plant required two months of cold temperature to resume growth. In fact there were no special similarities to the parent plant.

It is not new to find hybrid tea roses producing climbing types. Hjort (3) reported that Killarney HT, Maman, and Catherine Mermet all gave rise through bud sports to climbing roses. The same author reported that climbing sports were known to revert to the bush form. It will be interesting to test the climbing sport of Better Times to see if its relationship can be detected.

Souvenir (Plant Patent 25 by A. N. Pierson in 1930) arose as a bud sport of Talisman. The latter is said to be a hybrid between Pernet and Ophelia strains. Talisman has given rise, perhaps through somatic segregation, to many bud sports with fairly stable characteristics. When Souvenir, however, was propagated from root cuttings a strain with Talisman-like characters appeared. These have been propagated from both stem and root cuttings without change of characteristics. It appears, therefore, that Souvenir is a periclinal chimaera with a central core of Talisman. Endogenous buds arising from this core in turn produce the pure line Talisman strain. Three generations of root cuttings continued to make the Talisman-like variety. An unidentified garden type of a deep red hybrid tea rose gave rise to plants with pink flowers when propagated from root cuttings. The buds appear to be of endogenous origin and to arise from the core of a chimaera.

There are many varieties of garden and greenhouse roses with unknown ancestry. Through the use of root cuttings or other means of producing plants from adventitious buds it might be possible to obtain some information on the ancestry of named varieties of roses. Bateson (1,2) reported that in Bouvardia some double flowering types give rise to single flowers when propagated from root cuttings. A variety called Bridesmaid (double pink) regularly gave rise to a double scarlet when propagated from root cuttings. Pelargonium varieties propagated from "suckers" or root cuttings differed from the parent plants in color of the flowers as well as in their phenotypic characteristics. Bateson said that whenever plants grown from root cuttings differ from those grown from stem cuttings it may be inferred that the plant is a periclinal chimaera in which the cortex differs from the central tissue (core).

In the case of rose sports reported herewith only one arose from a natural stem bud of Briarcliff variety. All others came from adventitious buds of stems or roots. Those from the stems arose as suckers from internodal tissue growing underground. With the exception of one case, the adventitious buds on both stems and roots gave rise to the same kind of plants for any given variety. In general, therefore, the adventitious buds appear to be of endogenous origin. No explanation can be given for the exception where a root cutting gave rise to a climbing rose.

SUMMARY

A new kind of rose (sport) appeared on a branch of Briarcliff variety. The new rose flower was single and pink. The parent plant was a double pink. When plants of the sport were propagated from stem cuttings, they continued to show the same characteristics. When plants were propagated from root cuttings involving adventitious buds, they reverted to the original Briarcliff variety.

The variety Better Times came true to type when propagated by stem cuttings but reverted to Briarcliff characteristics when propagated from root cuttings. Also another unidentified red rose produced pink flowers when propagated from root cuttings.

Souvenir variety (yellow) which is known to be a bud sport of Talisman (red) gave rise to Talisman type plants from root cuttings.

It was concluded that the rose varieties described were probably periclinal chimaeras and that plants arising from adventitious buds of endogenous origin were like the variety which constituted the stele (core).

LITERATURE CITED

  1. Bateson, W. Root-cuttings, chimaeras and "sports." Jour. Genetics 6: 75-80. 1916/17.
  2. Root-cuttings and chimaeras II. Jour. Genetics 11: 91-97. 1921.
  3. Hjort, P. J. Sporting tendencies of newer vs. older roses. Amer. Rose Ann. 1938: 50-52. 1938.

It may be useful to consider Burdick's (1951) results from haploid tomatoes. Regenerating plants from adventitious shoots can give surprising results.


Dayton, D. F., 1970. New apple strains developed by forcing shoots on disbudded trees. Ill. Res. 12(2): 10.
Abstract: The technique of forcing adventitious shoots was used to test for genetic mutations in the internal wood of Golden Delicious, Mclntosh and several strains of Red Delicious. Disbudding had no effect on Golden Delicious, but one or more adventitious shoots formed on all the treated Mclntosh and Red Delicious trees. Of 25 trees developed from adventitious shoots, 15 exhibited fruit or tree characters more or less different from the source variety. Results from investigations of changes in fruit pigmentation indicated that cells may carry mutations affecting two or more characters and that the internal wood-may be heterogeneous, containing two or more kinds of genetically different tissues.