Pisum Genetics
2006—Volume 38
Research Papers
Two new pea mutations simultaneously affecting tendril and leaflet shape and plant internode length.
S. M. Rozov                                                                                                                  Inst. of Cytol. and Genet.
Siberian Branch of Russ. Acad. of Sci., Novosibirsk, Russia
During the screening of the EMS-treated pea line SGE, M2 progeny, the two new mutants SGE–0284 and SGE–1003 were isolated, characterized with the effect on tendrils and leaflet shape and also the internode length. These mutants are shown at Fig. 1.
Fig. 1. SGE-0284 and SGE-1003 plants: A – normal SGE        Fig 2. Leaves of the SGE-1003 mutant (brtl) —A, B;
plant; B – SGE-0284 mutant; C – SGE-1003 mutant.                leaves of the 0284 mutant (htl) —C, D; and the leaves
Note: the internode length of the mutants is slightly        of the normal SGE parental plant — E. (SGE-0284) and strictly (SGE-1003) diminished compared to the parental normal line, SGE.
The leaflets of the SGE–0284 and SGE–1003 mutants are also altered in shape: both of them have blunt tips, sometimes with a slight notch at the edge of a tip. Moreover, the SGE–1003 mutant has slightly raised veins on the leaflets, and the leaflets are somewhat insecatus. Fig. 2 presents the view of the mutants leaves.
However, the most striking changes in phenotype of the mutants plants concerned the shape of the tendrils. SGE–0284 possesses the deformed tendril tip—it looks like a hook or a chrochet needle (Fig. 3C), so I propose the symbol htl (hooked tendril) for this mutation. SGE–1003 mutant has an incrassate tendril base with the tendrils being strongly reduced in length. Lateral tendrils are incrassate, strongly hooked, and
17
Pisum Genetics
2006—Volume 38
Research Papers
declinated (Fig.3A). To the naked eye the tendrils look singed, suggesting analogy with the Bristle gene in Drosophila. Thus, I propose Bristle as the name for this pea mutation with the gene symbol brtl — Bristle tendrils.
In F2 progeny derived from crosses between the mutant line and line SGE, a segegation ratio not signifantly different from 3:1 was observed for both mutations, indicating a recessive monogenic basis for each mutation (Table 1).
Only a few genes affecting tendril shape have been described in Pisum sativum (1,2). None of these has the same phenotype as SGE–0284 or SGE–1003 mutant. The mutation bulf (3), is similar in that it affects only leaflets and tendrils. However, bulf produces necrotic areas on leaflet and tendril tips, while the described SGE mutants do not cause necrosis at all.
The allelic test between lines SGE– 0284 and SGE–1003 has shown that the mutations affect different loci – all five of the F1 hybrid plants examined were of the wild (normal) phenotype, as the parental pea line SGE.
Hence I must conclude that all phenotypic effects visible in the mutants SGE-0284 and SGE-1003 are produced by the action of one gene—htl in the case of SGE–0284 and brtl in the case of SGE– 1003.
Fig. 3. Tendrils of the SGE-1003 mutant — A; Tendrils of the normal parental line SGE — B; Tendril tips of the SGE-0284 mutant —C; tendril tips of the normal parental line SGE.
Table 1. Segregation in F2 progenies after the crosses between mutant lines SGE-0284 (htl) and SGE-1003 (brtl) with the parental line SGE.
Parental line Cross phenotype(normal)
Mutant phenotype               c2 3:1                       probability
SGE-0284 X SGE 86 
SGE-1003 X SGE 103
22 (htl)                   1.2346                     0.2 < p < 0.3* 
28 (brtl)                 0.9186                     0.3 < p < 0.4*

* -The segregation hypothesis 3:1 is well significant.

1.   Blixt S. 1972. Agri Hort. Genetica 30: 1–293.
2.  Pisum Genetics Association Gene List. Pgene. http://www.jic.ac.uk/GERMPLAS/pisum/Zgc4g.htm
3.  Sharma B. 1973. PNL 5: 46.
18