A Case of Mass-Occurrence of Non-Inherited Chlorophyll Defects in Wheat.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 63, 1934, Page 142

A Case of Mass-Occurrence of Non-Inherited Chlorophyll Defects in Wheat. By Dr. O. H. Frankel, N.Z. Wheat Research Institute. [Received by Editor, 12th August, 1932; issued separately, 28th February, 1933.] In contrast to the other cereals, chlorophyll defects in wheat are exceedingly rare. The only case, to the writer's knowledge, communicated so far showed a trifactorially inherited albino (Smith and Harrington, 1929). Stadler (1930) remarked upon the difficulty of tracing recessive mutants in polyploid species, owing to their gene reduplication. Plasmatic inheritance of chlorophyll defects, as found in barley and rice, has not been reported in wheat. In consequence some interest attached to the appearance of a comparatively large number of variegated wheat plants in the early spring of 1930. The affected plants were found in a collection of foreign varieties from various parts of the world. All except three variants were found in single-plant progenies, one (or, in two cases, two) variegated plants appearing in plots of 25 plants each. The seed of most of the lines containing defectives was obtained in 1929 and grown in the same year, the 1930 crop therefore being derived from seed raised in New Zealand. The varieties Marquis 10B and Victor, however, had been imported several years previously. Sowing took place from May 28 to June 4. The chlorophyll defects consisted in a distinct striping of the leaves, showing all gradations between a single narrow white line with the rest of the leaf green, and the opposite distribution. The stripes were clearly distinct, similar to those described for maize and barley, and were visible up to the dying off of the leaves. Two plants, which died at an early stage, were completely white. In some of the striped plants only the bottom leaves of the three primary tillers were affected, the younger leaves being completely green. The majority, however, showed striping up the third or fourth leaves, but two plants up to the fifth leaf, although with a decreasing amount of white lines in the younger leaves. One plant, ex C. No. 108 (Victor), was found only shortly before heading. Both its tillers had distinct yellowish stripes on all their leaves* In a violent storm shortly before harvest both ears were broken off the straws, having been tied to a stick. Ears in the vicinity of the plant were collected from the ground, but no chlorophyll defects appeared in the progeny.. In all plants the amount of striping varied considerably in the various tillers of the same plant. The affected lines included forms of the Spelta and Emmer Series (see table), both including varieties of varied origin. Since all variants were found by chance during field observation and cultivation, not in the course of a systematic search, it is more than likely that the actual number of variants present was a multiple of those identified. It is remarkable that not one variant was found in any of the older New Zealand varieties, although large plots of these were searched for the occurrence of defective plants.

Cons. No., 1930. Coll. No. Name and Origin. Number of Variegated Plants. Progeny Raised. Triticum vulgare. S 1237 Marquis 10B (Canada) 1 V 1 108 279 Victor (England) 1 1412 4 and 5 Serajevo 2 (Jugoslavia) 1 1543 267 Svalof's Riddar (Sweden) 1 V 12 1622 1282 Szekacs 17 (Hungary) 1 V 10 1534 287 Marster's New White Ideal (England) 1 V 13 1627 1287 Mindszenti 403 (Hungary) 2 V 11 1709 89 Belgrade 1 (Jugoslavia) 1 2086 622 Portugal 22 1 2572 1173 Duri (Australia) 1 3626 1358 Feldsberger Grannen Weizen (Czechoslov.) 1 1271 Kanred × Marquis (U.S.A.) 1 V 2 184 Dioseg No. 2 (Czechoslov.) 1 V 3 3289 1485 Persia 86 1 V 9 Triticum turgidum. 2738 E 56 Greece 24 1 (white) 2979 351 Egypt 18 1 V 4 3037 406 Egypt 69 2 3199 601 Iraq 19 1 3167 553 Cyprus 12 1 V 8 Triticum durum. 2801 E 129 Valencia 3 (Spain) 1 V 5 2817 146 Portugal 1 1 V 6 2818 147 Portugal 1 1 V 7 2838 169 Portugal 29 1 (white) Total: 25, in 23 lines. All seeds from 13 variants, including all the more pronounced cases of striping, were sown in 1931, and a systematic search for defective plants was conducted also in the Collection, consisting of over 2000 lines. However, no chlorophyll defects were found in the variant-progenies, nor in the Collection. The exceptionally hard winter of 1930 can hardly be adduced for causing these somatic variations, since the following winter, in the course of which no defects arose, was even harder. It is equally unlikely that the high temperatures probably encountered by the seed in the course of the transport to New Zealand may have caused these variations—in analogy to the heat-induced, apparently non-inheritable chlorophyll defects in maize (Hull and Grossman, 1932)—since the defects occurred in the second progeny from imported seed, and none had been found in the first generation. It seems more than likely that a plasmatic disturbance in the early embryonic stages caused the defects described. There appears to be a similarity to the heat-induced chlorophyll defects in maize (Hull and Grossman, 1932). However, no explanation can be offered as to the factor causing the defects in the former case. Literature Cited. Hull, F. H., and Grossman, E. F., 1932. Heat-induced Chlorophyll Mutations in Maize. Jour. Her. 23: 123–127. Smith, W. K., and Harrington, J. B., 1929. Wheat Albinos. Jour. Her. 20: 19–22. Stadler, L. J., 1930. Some Genetic Effects of X-Rays in Plants. Jour. Her. 21: 3–19.