II. 3. A mutant of barley: Awned palea.
H. Ahokas. Department of Genetics, University of Helsinki, P. Rautatiekatu 13, 00100 Helsinki 10, Finland. "R"
A female sterile mutant was observed in an inbred strain. The heads were abnormal, bearing additional awns. This turned out to be a true breeding characteristic, determined by a recessive factor (Table 1).
Table 1. F2 segregation results.
The observations have taken place in Finnish conditions. The palea tips are usually elongated into two long awns. The pistils are variably transformed into a leafy bud. Due to this transformation female fertility is low. The few caryopses are sometimes deformed. Usually, there are two good anthers, and a third one deformed to some extent. The mutant can readily be used as pollen parent in crosses. The named awned palea (adp) is suggested, since this is perhaps the most conspicuous characteristic.
Secondary shoots are usually more affected. The genetic background interferes: plants homozygous for e (elongated glume) set significantly more seed than plants with normal glume. In extreme cases, the mutant gives an appearance of vivipary. Natural viviparous variants are found in several grass species.
The segregation results are presented in Table 1. The female stocks of the crosses were: AHOR 226 cv. Svalofs Guldkorn 91 (e), AHOR 4405 cv. Triple Awned Lemma (tr or a similar mutant), and Takahashi's LT.26 (B, K, trd). The e mutant in AHOR 226 is allelic to that of Takahashi's linkage tester v-e-sk (BGN 2: 170-171). The stocks were obtained from Dr. Chr. O. Lehmann, and Dr. R. Takahashi.
The segregation results with LT. 26 are very limited. A linkage between the loci adp and b can be inferred from the low number of F2 plants. The loci e, k, and s are independent of the locus adp. The relationship of adp to tr and trd is not clear (Table 1). The following alternatives should be considered for the apparent absence of the double homozygous combinations adp, tr/adp, tr and adp, trd/adp, trd:
1. The combination is inviable or its viability is low (9:3:3:0).
2. The genes are allelic, however, resulting in a barely distinguishable mutant phenotype, which passed unnoticed in the F1 generation and was erroneously classified in F2 (9:3:4)
3. The genes are complementary, nullifying each other's effect and accomplishing the non-mutant phenotype (10:3:3).
Further work is needed to clarify.
Small amounts of seed of stock segregating the mutant are available upon request for those interested in allocating the locus. The mutant was also sent to Barley Genetic Stock Center (Fort Collins).
