Dedicated to Prof. Eviatar Nevo on the occasion of his 70th birthday. (See Wasser 1999.)

While studying the nuclear gene frequency of fertility restorers for cytoplasmic male sterility, a number of wild barley (Hordeum vulgare ssp. spontaneum) accessions was also crossed with domesticated barley as the pollen donor, in which cv. Adorra usually served as the pollen parent. The F₁s were monitored for the presence of spike fertility and were usually backcrossed with domesticated barley. Some F₁s showed partial fertility, backcrossed F₁s (BC-F₁s) segregated completely fertile and partially fertile plants. A total of 248 accessions were tested, showing 4.8% partially fertile F₁s with cv. Adorra (Ahokas 1981). Additional crosses have been performed and several previous crosses replicated with other domesticated barleys including Bomi, Bomi mut. 1508, Camir, HA 146-04-1, Koral, Kustaa, and Triumph. These domesticated barleys showed fertility results no different from those with cv. Adorra. The classification is presented in Table 1, showing the distribution in geobotanical territories in Israel and Jordan and including 12 accessions from the same region without information on the territory.

The 278 accessions showed 16 (5.8%) F₁s with partial fertility. One of the F₁s showed floret sterility more frequently toward the tip of the spikes; this accession 79BS14-3 later proved to be the carrier of the male-sterilizing cytoplasm msm2 with partial nuclear restorers of fertility (Ahokas 1982). PI 391107 showed completely fertile F₁s but segregated 9 fertile and 1 partially fertile BC-F₁s and was classified as fertile in Table 1. Likewise, several occurrences of partial sterility in later generations were found in several accessions; these may have been caused by minor rearrangements in the genome leading to aberrant recombinants. PI 282577 showed male sterility of a putatively genic nature. Mutation events in the recombinants upon selfing were common. The partial sterilities classified in Table 1 appeared at levels of about 25-35% and were most probably caused by translocation heterozygosity. The figures are similar to those described for barley translocation heterozygotes (Burnham et al. 1954). Those accessions exhibiting chromosomal interchange when compared with cv. Adorra are as follows: PI 296932, PI 296933, PI 296934, PI 296945, PI 354926, PI 405144, PI 405177, PI 405204, PI 405205, PI 405206, PI 405321, PI 405323, PI 405324, PI 405325, PI 405345, and 79BS28-A.

The distributions of territories having more than 10 observations (items 3, 8 - 10, 13, 15, 16) were tested in a 7 x 2 table: X² = 15.555, df = 6, P = 0.016. Although the sample is small in the partially sterile column, the test can be regarded as indicative of territorial differences in the occurrences of such interchanges. The northern coastal territories and Lower Galilee (items 3, 4, 10, 18) evidently show chromosomal interchanges most frequently; the southern Negev samples (item 13) contained none among the 38 accessions crossed. Occurrence of the chromosomal interchanges may be associated with environmental factors, especially with the availability of water. Nonrandom distributions of translocations were likewise found in the Israeli wild tetraploid wheat (Triticum turgidum ssp. dicoccoides) studied by Joppa et al. (1995). The present distribution of 262:16 is not significantly different from that of 113:7 demonstrated by Konishi ? Linde-Laursen (1987) for wild barley: P = 0.976. The origin of their material was not described in detail.

Acknowledgements

The PI accessions were obtained from the US Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA. Other material of wild barley was obtained from Prof. Moshe Feldman, Weizmann Institute of Science, Rehovot, Israel and from Prof. Eviatar Nevo, Institute of Evolution, Haifa University, Haifa, Israel.

References

Table 1. Fertility in crossed ssp. spontaneum accessions classified in F₁ and usually confirmed in BC-F₁ with domesticated barley