The Journal of Heredity 2002:93(5)
© 2002 The American Genetic Association 93:380-382
Brief Communication |
Inheritance of a Novel Flaccid Mutant in Capsicum annuum
From the Department of Agronomy and Horticulture, New Mexico State University, Las Cruces, NM 88003. This article is a contribution of the New Mexico Agriculture Experiment Station, New Mexico State University, Las Cruces, NM.
Address correspondence to P. W. Bosland at the address above, or e-mail: pbosland{at}nmsu.edu.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResults and DiscussionReferences |
|---|
A mutant that causes a novel flaccidity phenotype in bell pepper (Capsicum annuum L.) was generated by treating seeds with ethyl methanesulfonate (EMS). Inheritance studies indicated that the mutant was controlled by a single recessive gene. It is proposed that the gene designation representing this mutation be flc (flaccid). The mutation may be useful for investigations of the genetic basis for turgor maintenance and drought stress physiology.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
|---|
Mutants with a flaccid (or wilting) phenotype have been useful in understanding stomatal control and water stress physiology. Some of these mutants have shown the role of abscisic acid (ABA) in stomatal control (Jones et al. 1987; Wang et al. 1984); however, flaccidity or wilting is not always associated with ABA (Rock and Ng 1999). Nevertheless, plants with a wilty or flaccid phenotype do give plant physiologists and geneticists useful research material for studying the function of plant genes controlling transpiration, and therefore they can be useful genetic material for the study of stress physiology.
Flaccid phenotypes have previously been described, albeit indirectly, in Capsicum (Bergh and Lippert 1964; Csillery 1983). Diminished morphology (dm), a mutant that has diminutive leaves and small flowers, becomes flaccid under moderate water stress (Csillery 1983). The mutant scabrous diminutive (sd) is described as having foliage with a rough surface as compared to a normal plant's glossy surface and is said to be flaccid (Bergh and Lippert 1964). Bergh and Lippert (1964) also reported that the mutant, spinach (sp), which has leaves reminiscent of spinach (Spinacia oleracea L.), had petioles and leaves that were limp.
This article describes a novel mutation in Capsicum associated with a flaccid phenotype of both cotyledons and mature leaves. The mutant has a normal phenotype in leaf shape, size, number, and surface texture. But the mutant plants begin to exhibit a flaccidness to the leaves whenever there is high transpiration demand (Figure 1).
|
The new mutant was discovered in the M3 progeny of a commercial cultivar, Keystone Resistant Giant No. 3, which had seed subjected to ethyl methanesulfonate (EMS) treatment (Alcantara et al. 1996). The flaccid trait is visible throughout plant development. The cotyledons are first to show the manifestation of the mutant gene (Figure 1, left panel). Then true leaves exhibit the flaccid condition (Figure 1, right panel). The mutant becomes flaccid under typical field and greenhouse conditions, where the standard cultivar, Keystone Resistant Giant No. 3, leaves remain turgid. The mutation is clearly expressed in plants grown in soils that are nearly saturated with water. In soils with adequate water, the cotyledons and leaves recover turgidity during the night hours, but the next day the flaccidity reappears as increased transpiration imposes new demands on the water economy of the plant.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
|---|
A commercial bell pepper cultivar, Keystone Resistant Giant No. 3, was subjected to a treatment of EMS consisting of 10°C, 3 h of exposure, and 1.5% v/v. Seeds were presoaked in distilled water for 12 h in an Erlenmeyer flask at 24°C prior to seed treatment. After presoaking, 100 seeds were placed in 100 ml of solution. EMS solution was prepared in a 0.1 M phosphate buffer, pH 7.0, to avoid rapid hydrolysis. After the treatment the seeds were washed for 45 min with 0.5% ethyl acetate prepared in 0.1 M phosphate buffer, pH 7.0. The seeds were then washed with 5 mM sodium thiosulfate, pH 9.0, for 45 min, and air dried (Narayanan and Konzak 1969). The treated seeds were sown inside a greenhouse in a 51.5 cm x 25.5 cm x 5.7 cm plastic tray containing a commercially prepared peat moss/vermiculite mix. The trays were watered at least once a day and fertilized with a slow-release complete fertilizer (Osmocote 14 N/6.2 P/11.6 K) to maintain optimal seedling growth.
The flaccid mutant was hybridized with the normal parent, Keystone Resistant Giant No. 3. Reciprocal hybridizations were made. The F1 generation was selfed and backcrossed to the parents. The F1, F2, and backcross generations were grown in a greenhouse under normal greenhouse conditions. Inheritance analyses were performed using the SAS computer program (SAS Institute 1999).
|
Results and Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
|---|
Seed germination of the mutant, flaccid, was as good as the standard cultivar, Keystone Resistant Giant No. 3. Furthermore, the young seedlings of both the normal and the mutant grew similarly, except that the mutant exhibited a flaccidness around the cotyledon and leaf edges. The flaccidness in the cotyledons was apparent 7 days after germination and continued to display the phenotype in the true leaves. Normal plants and mutant plants flowered and fruit matured at the same time.
All the F1 plants were normal, healthy, and vigorous, showing no flaccidness. In the reciprocal F2 generations, the frequencies of normal and flaccid plants closely fit a 3:1 Mendelian ratio (Table 1), indicating that the flaccidness is governed by a single recessive nuclear gene and that the cytoplasm does not have an effect on expression of the trait. The backcross of the F1 plants to the parents had frequencies of normal and flaccid plants that support the observation that a single recessive gene controls the trait (Table 1). Hybridizations to the other known wilting mutants—that is, dm, sd, and sp—could not be accomplished because they are extinct. Thus it is currently impossible to determine if one of these genes might be the flc gene described here.
|
It is proposed that the gene designation representing this mutation be flc (flaccid). The flaccid mutant may prove useful for investigations of the genetic basis of turgor maintenance and drought stress physiology because of its high expression under normal greenhouse conditions. A small seed sample of the flc mutant is available from the Chile Pepper Institute, MSC 3Q, New Mexico State University, Las Cruces, NM 88003 (www.chilepepperinstitute.org).
|
Footnotes |
|---|
Corresponding Editor: William F. Tracy
Received May 13, 2002
Accepted September 5, 2002
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
|---|
-
Alcantara T, Bosland PW, Smith DW, 1996. Ethyl methanesulfonate-induced seed mutagenesis of Capsicum annuum. J Hered. 87:239-241.
Bergh BO, Lippert LF, 1964. Six new mutant genes in the pepper, Capsicum annuum L. J Hered. 55:296-300.
Csillery G, 1983. New capsicum mutants found on seedling, growth type, leaf, flower and fruit. In: EUCARPIA. Proceedings of the 5th meeting of the Capsicum and Eggplant Working Group, July 4–7, 1983, Plovdiv; 127–130.
Jones HG, Sharp CS, Higgs KH, 1987. Growth and water relations of wilty mutants of tomato (Lycopersicon esculentum Mill.). J Exp Bot. 38:1844-1856.
Narayanan KR, Konzak CF, 1969. Influence of chemical post-treatments on the mutagenic efficiency of alkylating agents. In: Induced mutation in plants. Vienna: IAEA; 281–301.
Rock CD, Ng PPF, 1999. Dominant wilty mutants of Zea mays (Poaceae) are not impaired in abscisic acid perception or metabolism. Am J Bot. 86:1796-1800.
SAS Institute,, 1999. SAS, version 8.00. Cary, NC: SAS Institute.
Wang TL, Donkin ME, Martin ES, 1984. The physiology of a wilty pea: abscisic acid production under water stress. J Exp Bot. 35:1222-1232.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||