Plant regeneration and chromosome instability in tissue culture of Elymus canadensis × E. trachycaulus F₁ hybrid

Abstract

KUMAR, P. S., and WALTON, P. D. 1992. Plant regeneration apd chromosome instability in tissue culture of Elymus canadensis x E. trachycaulus F, hybrid. Genome, 35: 88-91.Callus was induced from pieces of immature inflorescence of a sterile F, hybrid (2n = 4x = 28) between Elymus canadensis and E. trachycaulus on MS medium supplemented with 2 mg/L of 2,4-D. Calli were of two types: compact or soft. Regeneration occurred predominantly from the compact callus. Although some plantlets were obtained on the callus initiation medium, the frequency of regeneration increased considerably when the callus was transferred to an auxin-free MS medium. Deliberate aging of callus induced cytological instability and variation in chromosome number of the regenerants. Five of the 43 regenerated plants had deviant chromosome numbers, including an octoploid (2n = 8x = 56). Chromosome pairing in the octoploid plant suggests that it originated through chromosome doubling. Key words: callus culture, variation, chromosome number. KUMAR, P. S., et WALTON, P. D. 1992. Plant regeneration and chromosome instability in tissue culture of Elymus canadensis x E. trachycaulus F, hybrid. Genome, 35 : 88-91. Des pieces d'inflorescences immatures, provenant d'un hybride F, sterile (2n = 4x = 28) entre 1'Elymus canadensis et 1'E. trachycaulus et cultivees sur un milieu MS enrichi de 2 mg/L de 2,4-D, ont produit des cals. Deux types de cals ont ete obtenus : des compacts et des mous.La regeneration s'est operee de f a~o n dominante a partir des cals compacts. Bien que certaines plantules aient ete obtenues sur le milieu d'initiation des cals, la frequence de regeneration a ete considerablement augmentee lorsque les cals furent transferes sur un milieu MS depourvu d'auxines. Un vieillissement provoquk des cals s'est traduit par de l'instabilite cytologique et des la variation dans les nombres chromosomiques des plantes regenerees. Sur 43 plantes regenerees, cinq d'entre elles ont possede des nombres chromosomiques deviants, incluant une plante octoploi'de (2n = 8x = 56). D'aprks les appariements des chromosomes chez cette octoploi'de, un doublement des chromosomes serait a l'origine de cette plante.

Germplasm and Cultivar Development

“…Inflorescences of hybrids have been cultured in an attempt to obtain amphiploids. Inflorescences of Italian ryegrass x tall fescue (Kasperbauer et al, 1979;Rybczynski et al, 1983); Wimmera ryegrass x tall fescue (Rybczynski et al, 1983); and slender wheatgrass x Canada wildrye (Kumar & Walton, 1992) hybrids have been successfully cultured for this reason.…”

Field Testing Bacterial Wilt-resistant Tomato Somaclones

“…These mutations generally made the fruit commercially undesirable. Aberrations in chromosome number, mosaicism, have been detected in regenerants of other species or their hybrids (Fedak and Grainger, 1986;Alicchio et al, 1984;Kumar and Walton, 1992;D'Amato et al, 1980) This chromosome mosaicism, in part, may account for the undesirable traits. Crossing to incorporate the bacterial wilt resistance into the original 'Healani' is a possibility; however, the undesirable traits and the chromosome mosaicism may make it too cumbersome and costly to achieve benefits.…”

Somaclonal Variation in Tissue Culture of Triticum aestivum×Agropyron desertorum F1 Hybrid

“…In previous reports of regeneration in intergeneric Triticeae hybrids, the immature inflorescences used to initiate cultures and shoot induction were usually classified on the basis of length rather than the developmental stage (SHARMA et al 1984, CHU et al 1984, FEDAK 1985, DoRE et al 1988, MOLNAR-LANG et al 1991, KUMAR and WALTON 1992. The length of an inflorescence, however, gives a poor indication of developmental stage since this varies between hybrids.…”

“…Many variations in agronomic and quality characters such as the presence or absence of awns, plant height, seed set, gliadin proteins, a-and ^-amylases, and tolerance to frost and to aluminium have been reported (LARKIN et al 1984, MADDOCK and SEMPLE 1986, GALIBA and SUTKA 1989 and JOHNSON 1989, MOHMAND 1991. With the intergeneric hybrids in Triticeae, however, research on somaclonal variation in tissue culture has mainly focussed on cytological variation, including chromosome number, chromosome structure and meiotic behavior (LAPITAN et al 1984, FEDAK 1985, FEDAK and GRAINGER 1986, DoRE et al 1988, KUMAR and WALTON 1992. Detailed observations on morphological variation, in contrast, are only to be found in a paper by MOLNAR-LANG et al (1991).…”