II. 7. Lysine content in relation to endosperm characteristics in selected barleys from a Hiproly cross.
W. C. Burger, J. E. Carden III, and D. M. Wesenberg, U.S. Department of Agriculture, Agricultural Research Service, Barley and Malt Laboratory, Madison, WI 53705 and Aberdeen Research and Extension Center, Aberdeen, ID 83210, U.S.A.
F4 and F5 lines (or populations), each derived from single F2 plants from 61Ab4965-A/'Hiproly', were grown under irrigation at Aberdeeen, Idaho in 1971 and 1976, respectively. 61Ab4965-A, a hulled two-rowed cultivar, originated at Aberdeen as an F11 selection from 'Piroline'/Australian. (Australian is equivalent to CI 3038.) Individual kernels of 64 F4 hulless and 72 F4 hulled lines were examined and classified for apparent endosperm character - either shrunken, partially shrunken, or normal endosperm. The F4 lines examined varied widely with respect to the distribution of the shrunken vs. normal endosperm character. Analysis of individual kernels from both hulless and hulled lines for lysine content showed that, although the kernels with normal endosperm usually had a lower lysine content as a percent of protein than the kernels with shrunken endosperm, certain of the normal kernels contained relatively high levels of lysine.
Lysine content of barley protein was assayed by the ninhydrin colorimetric method of Beckwith et al. (1). High correlations (r = 0.90-0.94) were found in comparison of data by the ninhydrin colorimetric method (2) with those obtained by conventional ion-exchange chromotographic analysis (3). Lysine content determined by the ninhydrin colorimetric method is referred to here as "lysine index", which is A580/g. barley as is.
Between 7 and 28% of the kernels of 10 high-lysine, high protein hulless F4 lines were normal in endosperm appearance (Table 1). The lysine indices of such normal endosperm kernels from some lines approximated that of the partially-shrunken Hiproly kernels, e.g., lines M174, M247, M335, and M349. However, lines with relatively high kernel weight had lysine indices for the normal endosperm fraction similar to that of 61Ab4965-A, e.g., lines M213 and M284. A comparison of results obtained using 2, 4, or 6 kernels for lysine analysis indicated less than 5% variation in the mean value; the corresponding variation for kernel weight was less than 16% for F4 barley lines and less than 8% for F5 spikes.
About 200 F5 spikes were randomly harvested from nine hulless lines grown in four-row plots at Aberdeen in 1976. With the exception of M16, all F5 lines grown in 1976 are referred to in Table 1. Each line was represented by 16-26 F5 spikes with an average of 21 spikes per line. In general, the F5 material had an endosperm character distribution similar to that of the F4 material. Spikes having 50% or more kernels with normal endosperm were selected and two normal kernels from each spike were analyzed for kernel weight and lysine index. Data for the 15 spikes having the highest average lysine index are summarized in Table 2. Several of these spikes were composed entirely of normal endosperm kernels; however, only one, M126-40, approximates the lysine content of Hiproly. The kernel weight of M126-40 was, however, similar to Hiproly despite the normal endosperm. Although only intermediate between the parents in lysine content, M16-20 is also of interest because of its normal endosperm character and high kernel weight. These F5 selections are currently being increased in the greenhouse to obtain seed for more detailed agronomic and biochemical evaluations in 1977.
Table 2. Kernel characteristics of selected F5 spikes of hulless lines from 61Ab4965-A/Hiproly.
A similar approach is being used in evaluations of the 72 hulled lines from the same cross, 61Ab4965-A/Hiproly. The hulled lines have an average lysine index which is much closer to that of the low-lysine parent, 61Ab4965-A, than the hulless lines. Factors other than the physical presence of the hull may be involved, however, since the lysine content of the barley hull is relatively high (4).
References:
Beckwith, A. C., Paulis, J. W., and J. S. Wall. 1975; Direct estimation of lysine in corn meals by the ninhydrin color reaction. J. Agr. Food Chem. 23:194-196.
Robbins, G. S., and J. T. Gilbertson, unpublished results.
Robbins, G. S., Pomeranz, Y., and L. W. Briggle. 1971. Amino acid composition of oat groats. J. Agr. Food Chem. 17:536-539.
Pomeranz, Y., Robbins, G. S., and J. T. Gilbertson. 1976. Protein content and amino acid conposition of tissue components in developing barley. J. Food Sci. 41:283-285.
