| Effects of the nuclear-cytoplasmic interaction on grain
protein in wheat M. SASAKI, Y. YASUMURO and N. NAKATA Faculty of Agriculture, Tottori University, Tottori 680, Japan In order to elucidate whether or not so called "cytoplasmic heterosis" (KIHARA 1963) can be utilized for improvement of wheat protein (SASAKI et al. 1977, 1978), 4 alloplasmic ditelocentric (DT) line groups of Chinese Spring (CS) were analysed for grain protein and amino acid composition together with a number of plant characters. In this report the results obtained in 1979-1981 will be summerized on percentage grain protein (%P) and lysine content per protein (%L) of 95 DT and 5 euploid lines of CS each with one of the T. aestivum (original), Ae. speltoides, Ae. ovata, Ae. variabilis, Ae. squarrosa cytoplasms. Alloplasmic CSDT lines were developed in the Laboratory by crossing between alloplasmic CS and respective CSDT lines, which were developed by E.R. SEARS ( 1954). A single-plant randomization design was used with three replications having 2 plants within each replicate block. Nitrogen was determined by the Carlo Erba Model 1300 Automatic Nitrogen Analyser. Total nitrogen x 5.83 was used to convert nitrogens to protein values. For each line 6 ground wheat samples were analysed 3 times within each sample. Amino acid composition was analysed by the Shimazu HPLC Model LA3 Amino Acid Analyser using 3 samples for each line, with 2 determinations within each sample. Appropriate statistical adjustments were made to analyse the combined data of three different years. The %P means of CSDT lines examined varied from 11.1% for DT7BL with speltoides cytoplasm to 23.8% for DT2AS with speltoides, and most of them were higher than that of the CS euploid with aestivum cytoplasm. However, since the %P were correlated negatively with yield component characters, the %P were adjusted by the regression based on the seed fertility. A relative genetical effect of each line on %P was estimated by the difference between each line and the CS euploid in its own cytoplasm (Table 1). The genetical effect of 5.1% for DT6AS was significantly larger than that of 1.6 % for the control CS euploid by the Tukey' test. This indicates that the long arm of CS chromosome 6A may carry the inhibiting gene or genes for protein content. That the cytoplasm means of ovata and variabilis were significantly lower than that of the control aestivum suggest that both cytoplasms may decrease %P of CSDT lines though that of the CS euploid with these cytoplasms was not low comparing with the euplasmic euploid. The interaction effects between CSDT lines and cytoplasms were also found in some lines such as DT6AS with aestivum, 6AS and 7DS with speltoides, 5AL with squarrosa cytoplasm. In a similar way the genetical effect of each line on %L was calculated (Table 1). As for %L only cytoplasmic effects were significant of variabilis and squarrosa, but neither nuclear or nuclear-cytoplasmic interaction effects. However, by the Duncan's Multiple Rang test, which is not severe as the Tukey's test, genetical effects of some lines became significant in either or both %P and %L. These results indicate that several genes and interactions with smaller effects than those already mentioned may also be involved. Further studies in detail are necessary to clarify the above mentioned points including the role of squarrosa cytoplasm which seems to increase both %P and %L of certain genotypes of CS, in wheat protein improvement. We are grateful to Dr. K. NISHIKAWA and Drs. H. FUKASAWA, K. TSUNEWAKI for providing us with the source seeds of CSDT lines and with the cytoplasm source line seeds, respectively. A part of this work was supported by a Grant-in-Aid from the Ministry of Education, Science and Culture. Japan and from the International Atomic Energy Agency, Vienna. |