Normal, Illinois

Illinois State University

A survey of ig containing materials --Schneerman, MC, Charbonneau, , M, Weber, DF The indeterminant gametophyte (ig) mutation was recognized by Kermicle (1969, Science 166, 1422-1424) to produce haploids with a frequency of nearly 3%. This mutation can be used to produce paternal haploids whose chromosomes then can be doubled. These plants are diploid and homozygous at all loci and contain the cytoplasm of the female parent. This mutation therefore has been recognized as potentially useful for placing a given nuclear germplasm in a different cytoplasm. This is of interest to the seed industry because it would make it possible to place a nuclear genome in a different cytoplasm in far fewer generations than by using conventional backcrossing.

In an effort to identify the efficacy of this mutation, several stocks containing ig in different genetic backgrounds were grown and crossed as female parents by an unrelated glossy (gl) tester with normal cytoplasm (Table 1). Progeny were planted in the sandbench and individual gl plants were identified to determine the frequency of androgenic plants produced by each genotype. To verify that the gl plants were indeed haploids, root tips were harvested and the ploidy level of each plant determined cytologically by counting the metaphase chromosomes of at least 3-5 cells. Several androgenic diploids (10.8%) were also recovered in this study, a result consistent with Kermicle’s observations (1974, p. 137 in Proc. First Intnl. Symp. on Haploids in Higher Plants, ed. K. Kasha, Guelph, Canada).

The materials from the Stock Center that were originally provided by B. Kindiger which should have possessed two normal chromosome 3's with ig and a B3-Ld with Ig did not produce the expected plant types in our hands. Every one of these stocks produced large numbers of small plants that had a distinctive abnormal phenotype that was different from the phenotype of haploids. This abnormal phenotype was the same as plants that had lost much of the long arm of chromosome 3 or all of this chromosome (hypoploid for 3L or monosomic for chromosome 3). Furthermore, these exceptional plants were examined cytologically and were found to contain 20 chromosomes. From these and other observations, it appears that the complete B-A translocation was present in these stocks and that the chromosome constitution was not as described by Kindiger and Hamann (1993, Crop Sci. 33:342-344). Also, the frequency of haploids produced by these stocks was much lower than reported by Kindiger and Hamann (1993). The materials provided by J. Laughnan (Stock Center) were also difficult to discern. The fact that the plants were not definitely male sterile and did not produce haploids in the expected frequency suggested that ig was segregating, or a restorer gene was segregating. Certain plants of the two stocks originally provided by R. Brawn and D. Alvey that had been maintained for over 25 years in our culture collection did produce higher frequencies of paternal haploids than the other stocks, 1.67% and 1.18% respectively. The reason for this is unknown. The materials provided by Jerry Kermicle produced paternal haploids but at a lower frequency than expected. This survey has allowed us to determine which ig containing materials produce paternal haploids with the highest frequency and also suggests that genetic background is important.

Table 1.
 
Source/Stock Total # grown Total gl identified Total # AndrogenicHaploids Total # Paternal Diploids % Androgenic Haploids/ Diploids produced
B. Kindiger (several cytoplasms) provided by the Stock center 5331 24 20 4 0.45%
J. Laughnan (various lines & cytoplasms), provided by the Stock center 6503 6 6 0 0.09%
Originally from Bob Brawn (Funks) N cytoplasm; D. Weber’s collection 3482 13 12 1 0.09%
Originally from Bob Brawn (Funks) C cytoplasm; D. Weber’s collection 2234 8 6 1 0.37%
Originally from David Alvey (Indiana); D. Weber’s collection 1553 26 26 0 1.67%
Originally from Jerry Kermicle, U of Wis.;D. Weber’s collection 936 5 3 2 0.53%
Originally from Bob Brawn (Funks) C cytoplasm; D. Weber’s collection 2120 25 24 1 1.18%
Jerry Kermicle; U of Wisconsin 1739 8 8 0 0.46%
Jerry Kermicle; U of Wisconsin 1456 1 1 0 0.06%
Originally from Bob Brawn (Funks) N cytoplasm; D. Weber’s collection 1013 4 2 2 0.39%

 


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