GrainGenes
A Database for Triticeae and Avena
Shahla and T. Tsuchiya, pp. 94-95
II. 45. A new trisomic type in the progeny of Triplo 1S.*
Azizeh Shahla and T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U.S.A.
*This work was supported in part by the USDA Research Grant, 12-14-5001-265 to T. Tsuchiya.
In the progeny of Telotrisomic 1S (Triplo 1S) in the variety Shin Ebisu 16 (S.E. 16) a new trisomic plant was obtained which had a new extra chromosome. The extra chromosome is shorter than the primary chromosome 1 and submetacentric indicating deficiency or deficiencies in one or both arms.
Morphological traits of this plant resemble very closely those of Telo 1S and normal diploid. As shown in Table 1 there are some quantitative differences in morphological measurements between this plant and diploid or Telo 1S; shorter culm and awn length and longer leaves of the new trisomic plant.
Table 1. Measurements (cm) of the new trisomic (2n=15) compared with Triplo 1S and diploid.
The plant is very vigorous. The seed fertility is very high, with average 88 percent in selfing and 57 percent in crosses 2x+1 x 2x.
The total of 11 selfed seeds were all germinated (100 percent), with four plants having 2n=15 chromosomes. The extra chromosome in all trisomic plants seems to be the same submetacentric as that in the parental plant.
Chromosome configurations were studied in MI of meiosis. The number of cells with 7II + 1 I was 31 percent of the total 100 sporocytes. The trivalent configurations in the sporocytes with 6 II + 1 III were frying pan (29%) followed by V-shape (24%) and rod-type (16%). At AI the chromosomes separated to 7-8 in 70 cells, and 7-1-7 and 7-1-1-7 distributions in 23 and 7 cells, respectively, in total of 100 cells studied.
Since the morphology of this plant was almost the same as normal diploid plants, it was assumed that the plant was the secondary trisomic for the short arm of chromosome 1 (1S). However, detailed study of the karyotype in this new trisomic plant showed that the extra chromosome was shorter than the expected secondary or isochromosome for 1S. The meiotic chromosome behavior also showed that the extra chromosome may not be iso- or even pseudo-isochromosomes for 1S, since the trivalents did not show ring-of-three but showed similar configurations to the primary type.
The exact nature of the extra chromosome of this plant is not clear yet, but the Giemsa c-banding technique will be used for detailed study of the extra chromosome in the near future.