Guard Cell Length Research Articles

Aspects of growth and morphology of seedlings of diploid and tetraploid western Wolths ryegrass

Summary The tetraploid plants had a lower relative growth rate, and were larger with larger cells. Compared with the diploids, very young tetraploid plants in particular showed a difference in tissue proportions in the leaves. Because of the increased cell sizes and changed tissue proportions, the ratio of cytoplasmic to wall material was probably greater in the tetraploids. Stomatal guard cell length which has been used to distinguish between ploidy levels is not a satisfactory definitive measurement for distinguishing between the diploid and the tetraploid, nor are any of the other characters examined.

Studies on Restoration and Substitution of Nucleus (Genome) in <i>Aegilotricum</i>

1) Abnormal stomata, which appeared in the variegated leaves of cytoplasmic male-sterile durum plants were investigated cytologically and classified in six types according to two criteria, namely; degree of differentiation of guard cells and their nuclei, and abnormality or deficiency of subsidiary cells.2) Observation on the cross-section of variegated leaves revealed that the inner air space of the abnormal stomata was smaller than that of normal stomata and that palisade cells in the variegated portion were rather round and arranged irregularly.3) The frequency of occurrence of abnormal stomata was investigated. The percentage of abnormal stomata in the variegated portion reached as high as 38%, but the mean value in the variegated leaf was 12% in longitudinal and 9% in transverse directions. Mature leaves of male-sterile plants do not have abnormal stomata any longer (only 0.2% of the stomata was abnormal).4) Alteration of stomatal distribution was observed in the variegated leaves, that is; the average number of stomata per unit length is decreased in longitudinal direction and is increased in transverse direction, as compared to the number found in normal green leaves.5) It was ascertained from the x2-test that abnormal stomata did not occur at random in the variegated leaf, but occurred serially to a certain degree and that more series were found in longitudinal than in transverse direction.6) Cell length and nuclear length of guard cells in the variegated leaf varied widely and decreased in comparison with those of the normal green leaf. On the other hand, some subsidiary cells were increased in length (although the mean value of cell length was decreased). Width of cell and nucleus did not change to the same degree.7) A correlation between cell length and nuclear length of guard cells was found expressed by a correlation coefficient as high as +0.9137.8) The data presented lead to the assumption that an unknown cytoplasmic factor induces abnormal metabolism in winter leaves, leading to abnormal development of stomata, and on the other hand, to formation of abnormal chloroplasts. The abnormal stomata seem to accelerate the chlorophyll variegation.The present author wishes to express his cordial thanks to Dr. H. G. duBuy, National Institute of Allergy and Infectious Diseases, U.S.A., who was kind enough to read over the manuscript and make some corrections in the style.

Cytogenetical studies on the amphidiploid of Quamoclit

Cytogenetical studies on the amphidiploids raised from interspecific hybrids of Quamoclit by the colchicine treatment have been carried out by the author.In amphidiploids, the length of guard cells of stomata is larger than that of the parents, and about as large as that of Q. Sloteri (Table 3).Further, the size of flowers is larger than that of the parents (Fig. 2).In F1 plants, abortive pollen grains were observed in exceedingly higher percentage than in amphidiploids (Table 5). The size of pollen grains in amphidiploids is larger than that of the F1 (Table 6), i. e., nearly equal in size to the Q. Sloteri's.F1 plants were completely sterile, but the amphidiploids were fertile, though the percentage is low (16.04%).The fruits of amphidiploids were morphologically intermediate between parents of them.The weight of 1000 seeds of Q. coccinea, Q, coccinea var. hederifolia and Q. pennata were 11.6, 14.2 and 16.5grs respectively. And that of the amphidiploids from hybrid I and II were 30.1 and 32.6grs, that is nearly equal to the seed weight of Q. Sloteri, 31.6grs.The number of somatic chromosomes were 30 in Q. pennata (Fig. 7). 28 in both Q. coccinea and Q. coccinea var. hederifolia (Figs. 5 and 6). In F1 plants of Q. coccinea×Q. pennata and Q. coccinea var. hederifolia×Q. pennata, the number of chromosomes was 2n=29 (Figs. 8 and 9) in both cases. The number of chromosomes of amphidiploids raised from hybrid I (Q. coccinea×Q. pennata) and II (Q. coccinea var. hederifolia×Q. pennata) was 2n=58 in both combinations (Fig. 10). These numbers correspond to double the somatic number of F1 of hybrids I and II, viz. equal to the number of Q. Sloteri's chromosomes 2n=58 (Fig. 11).

The tetraploid plants in <i>Quamoclit</i> raised by the colchicine method

The writer tried to raise the tetraploids of Quamoclit with large flower that are more valuable as the ornamental plant, by treating three species snd one variety, i. e., Q. pennata, Q. cocccinea, Q. coccinea var. hederifolia and Q. sloteri with colchicine. In the treatment, the following three methods were employed; 1) the immersion of seeds in the dilute aqueous solution of colchicine, 2) the dropping of the same solution on germinating plants, and 3) the mounting of lanolin emulsion of colchicine on germinating plants. In these three experiments, I failed in 1) but succeeded in the others, in raising the tetraploids (Table 1). For discriminating tetraploids from diploid the results of measurement of the length of guard cells were used (Table 2, 5 and 9).In tetraploids raised, thickening of cotyledons, leaves and stems etc., the retardation of growth, and the increase in the size of pollen grains and stomata were observed, as the same in many cases of induced tetraploids in other plants. The leaves, however, were generally smaller in size but wider in tetraploids than in diploids. The diameters of flowers in diploids to those of tetraploids were 2:3 in Q. pennata, 5:7 in Q. coccinea and Q. coccinea var. hederifolia.In tetraploids, abortive pollen grains were observed in fairly higher percentage than in diploids (Table 7).The tetraploids of Q. sloteri were completely sterile, but the tetraploids in all other species and variety were more or less fertile. In Q. pennata, 17 seeds were obtained from 19 tetraploid individuals, and 10 plants of the next generation of tetraploids yielded 46 seeds. In Q. coccinea and Q. coccinea var. hederifolia the tetraploids were more fertile. Q. coccinea gave 1000 or more seeds from per. plant of tetraploids and in Q. coccinea var. hederifolia, 200 or more seeds were raised from each individual.The seeds of tetraploids were much larger than those of diploids. The weight of 1000 seeds of tetraploids to that of diploids was 23:10 in Q. coccinea and Q. coccinea var. hederifolia showed about the same size in pollen grains, stomata and external characters compared with tetraploids.The observation of chromosomes was not made in tetraploids raised by the treatment, but the somatic chromosomes of the plants in the next generation of them were observed in root tip cells. The number of chromosomes were 60 in Q. pennata (diploid 30), 56 in Q. coccinea and Q. coccinea var. hederifolia (diploid 28).