Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 1998
Publication Date: N/A
Interpretive Summary: This report describes the chromosome number and behavior, morphological variation, and maternal DNA type for the first time in a natural hybrid between bottlebrush squirreltail and Salina wildrye collected on the mountain ranges west of the Great Salt Lake. Whenever bottlebrush squirreltail and Salina wildrye were found growing together hybrids were observed. The hybrids had 28 chromosomes. The lack of chromosome pairing during meiosis demonstrated that the hybrid contained two sets of chromosomes from bottlebrush squirreltail and two from Salina wildrye. As a result of the different sets of chromosomes, the hybrids were completely sterile. Morphologically the hybrids were intermediate between the suspected parent species, but they resembled Salina wildrye more closely than bottlebrush squirreltail. Study of the chloroplast DNA demonstrated that bottlebrush squirreltail is the female and that Salina wildrye is the pollen source in this natural hybrid.
Technical Abstract: Several putative hybrids between Elymus elymoides (Rafin.) Sweezey and Leymus salinus (M.E. Jones) A. Love ssp. salmonis (C. Hitchc.) Atkins were found growing on the west side of the Great Salt Lake, near Lakeside, UT in 1995. Cytological, morphological, and chloroplast DNA analysis of the hybrids and parents confirmed the hypothesis that these plants were hybrids. Elymus elymoides and L. salinus subsp. salmonis were the only Triticeae species growing in the area that could have contributed to the intermediate morphological features expressed in the hybrids. Leymus salinus subsp. salmonis (NsNsXmXm; 2n=4x=28) and E. elymoides (StStHH; 2n=4x=28) are both allotetraploids that regularly formed 14 bivalents at metaphase I. The hybrids between the two are also tetraploids and averaged 22.1 univalents and 2.86 bivalent associations per cell at metaphase I. Chromosome pairing in the hybrid suggests essentially no homology between the chromosomes from the two parents, thus the genomic formula for the hybrid can be written as StHNsXm. The hybrids were morphologically intermediate between the suspected parent species, but they resembled L. salinus subsp. salmonis more closely than E. elymoides. Analysis of chloroplast DNA in the hybrid and its putitive parents, demonstrate cytoplasmic DNA, indicating that E. elymoides was the maternal parent.