BGN 9: Pollen lethals induced with sodium azide BARLEY GENETICS NEWSLETTER, VOL. 9, II. RESEARCH NOTES
Lehmann et al., pp. 57-58

II. 28. Pollen lethals induced with sodium azide.

L. Lehmann, P. Hagberg, and G. Hagberg, Swedish Seed Association, S-26800 Svalöv, Sweden. "R"

The term pollen lethal as used in this paper can also be termed gametic lethal or pollen sterility factor (let) as described by D. von Wettstein and K. Kristiansen (1973) and O. Nielsen (1974); C. A. Foster (1976) used "mge" as a symbol to describe his "male gamete eliminator"; "haplo-viable" as used by J. Hernandez (1975) also describes the same phenomenon.

Two populations of Fl's were treated with NaN3. One F1 population was heterozygous male sterile (Msg2 msg2) which produced pollen lethal No. 9. The second F1 population was from the cross msgl msgl x Tl-5a Msg 1 Msg 1, which produced pollen lethal No. 11. Progeny tests of the pollen lethal lines segregated approximately 1:1 (male sterile to fertile or semisterile in the case of the translocation heterozygote) in the F3M3 and F4M4 where plant counts were made. Sibling crosses were made within plant rows in the F5M5 between sterile and fertile plants. Table 1 shows the results of these crosses. It has not been determined if the fertile plants from these crosses are due to crossing-over or if this is the frequency of transmission of the pollen lethal. Studies are being continued on this aspect.

Table 1. Segregation data of sibling crosses of pollen lethal onto male sterile plants.

Both pollen lethals were checked cytologically at metaphase I and pollen was stained with lactophenol fuchsin. Pollen lethal No. 9 had only 7II (seven bivalents) and nearly all the pollen from fertile plants were stainable. Pollen lethal No. 11 plants that were fertile had 5II + lIV (five bivalents and one quadravalent) and sterile plants had 7II. Approximately 75-80% of the pollen from fertile plants of pollen lethal No. 11 were stainable. This is about normal for a translocation heterozygote. It is concluded from this that these pollen lethals are not pollen killers as such. The pollen lethal could be due to lack of competitive ability of the pollen carrying the lethal factor, or another possibility would be a malformation of the sperm or tube nuclei during microgametogenesis. The pollen lethal, therefore, could affect pollen germination. We are now trying techniques to determine the amount of pollen germination in these lines. If there is anyone who has a good method for an in vitro and/or in vivo barley pollen germination we would appreciate hearing from you.

References:

Foster, C.A. 1976. Natural and induced mutations in hybrid barley breeding. Barley Genetics III:774-784.

Hernandez-Soriano, J.M. 1975. Induction of haplo-viable mutants in barley (Hordeum vulgare L.). Dissertation, Univ. of Arizona, Tucson, Arizona.

Nielsen, O.F. 1974. Macromolecular physiology of plastids. XII. Tigrina mutants in barley: genetic, spectroscopic and structural characterization. Hereditas 76:269-304.

Wettstein, D. von and K. Kristiansen. 1973. Stock list for nuclear gene mutants affecting the chloroplast. Barley Genetics Newsletter 3:113-117.

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