II. 2. Further results on the suppression of shrunken endosperm in high lysine mutants.
H. Ahokas, Department of Genetics, University of Helsinki, P. Rautatiekatu 13, 00100 Helsinki 10, Finland. "R"
The distorting effect of Crypt CI 1090 on the F2 segregation of the high lysine mutant sex3c (Risø 1508) has recently been described (Ahokas, 1978a). Additional segregation data on the distortion in F2 kernels are presented in Table 1. Reciprocal hybrids with two sources of Risø 1508 and three single plant selections of CI 1090 all departed from the 1:3 segregation. However, three of the four results fit the 1:63 ratio, the four crosses showing no significant heterogeneity. The segregation of the non-allelic mutants sexla and sex4f (Ullrich and Eslick, 1978) are not distorted in F2 kernels of crosses with CI 1090 (Table 1).
Table 1. Segregation of F(2) kernels in F1 hybrids with Crypt, CI 1090 as one of the parents.
Two alien cytoplasms have been tested for a hypothetical suppressive action by the cytoplasmic factor. These are male sterile maternal 1, msml (Ahokas, 1978b) and the Hordeum bulbosum cytoplasm in HA-Hb-1-Karri (Ahokas, 1978c). The latter cytoplasm slightly normalized the appearance of Hiproly CI 3947 in BC3 material. The other mutants did not visibly differ from the control (Table 2). HA-Hb-l-Karri's starchy endosperm has an appearance different from that of normal Karri under SEM (unpublished), while msml was not found to change the SEM appearance (Ahokas, 1978b).
A number of distal kernel halves were analyzed with the micro-DBC analyzer system for the FP-9 Analyzer (Labsystems Oy). This FP-9 Analyzer system works in sets of 4 x 9 samples, with four sample places occupied by control flour tablets. The procedure is rapid. The results are printed directly in DBC mg/mg. The work was carried out according to the instructions (Anonymous, 1978), except that before weighing a pulverization in the FP-9 Mill, the kernel halves were crushed with pliers as described in Ahokas (1978d). Though it is recommended for single kernel determinations, the analyzer can distinguish between high and low DBC stocks even from distal kernel halves.
The results on Risø 1508, CI 1090, and three types of F2 kernel halves are presented in Figure 1. Risø 1508 has significantly higher DBC values than CI 1090. Since Bomi has a lower protein and a lower lysine content than CI 1090 (Ahokas, 1978a), heterosis of DBC protein in the F2 kernels of the cross Bomi-CI 1090 is evident. This heterosis may be due partly to a decrease in the kernel number per plant and a considerable tiller mass resulting from a two-rowed/six-rowed cross (see Ahokas, 1979). The shrunken Risø 1508/CI 1090-F kernels have a DBC similar to that of the kernels of Risø 1508. The plump Risø 1508/CI 1090-F2 kernels have a mean DBC significantly higher than that of Bomi/CI 1090-F2 kernels (t = 3.329, P < 0.001). The distribution probably displays some positive skewness. The last two features suggest that the plump F2 kernels include a fraction of high lysine kernels. Two maxima appear in the distribution of Risø 1508/CI 1090-F2 plump and perhaps in that of Bomi/CI 1090-F2. 2
Acknowledgments:
I am grateful to Dr. Osmo Suovaniemi (Labsystems Oy, Pulttitie 0, 00810 Helsinki 81, Finland) for providing facilities in the laboratory of Labsystems Oy for the analyses. The work was done under the auspices of the Academy of Finland.
References:
Ahokas, H. 1978a. Genetic suppression of shrunken endosperm in Risø Mutant 1508. Barley Newsletter 21:62-64.
Ahokas, H. 1978b. Cytoplasmic male sterility in barley. II. Physiology and anther cytology of msml. Hereditas 89:7-21.
Ahokas, H. 1978c. Male sterile mutants of barley. VI. Tests of restoration by the cytoplasm of Hordeum bulbosum, and reports of new mutants. BGN 8:12-15.
Ahokas, H. 1978d. A simple and rapid screening method for the determination of protein and tryptophan in kernel halves and small samples of barley meal. J. Sci. Food Agric. 29:47-52.
Ahokas, H. 1979. Cytoplasmic male sterility in barley. IV. Effect of msml cytoplasm and partial fertility on kernel protein and lysine. Submitted.
Anonymous 1978. Micro DBC method for single cereal seeds. Application for FP-9 Analyzer. 1 page (available from Labsystems Oy, Pulttitie 9, 00810 Helsinki 81, Finland).
Ullrich, S.E. and R.F. Eslick. 1978. Chromosome location evidence for Risø induced high lysine shrunken endosperm mutants of barley. BGN 8:114-125.
