Search Results
An in vitro method for obtaining bamboo mosaic virus (BaMV)-free plantlets of Bambusa oldhamii Munro was developed. BaMV-free meristems were incubated on MS basal medium supplemented with 0.45 μm thidiazuron (TDZ) to induce the development of multiple shoots. Multiple shoot proliferation was higher in stationary liquid culture than on semisolid medium. Cytokinin was the key component for inducing proliferation, and TDZ was the stable and effective cytokinin for proliferation in long-term subcultures. Multiple shoots rooted after 1 month in MS basal medium containing 10.74 to 26.85 μm α-naphthaleneacetic acid with a rooting efficiency of 83%. Healthy, well-developed plantlets were transferred to soil in pots and raised in a greenhouse. Those plants derived from tissue culture were more vigorous than the ones derived from the traditional in vivo vegetative propagation method, air layering. The tissue culture-derived plants could produce the culms after 15 months. Fifteen of 38 plants flowered 2 years after being transplanted to the field.
Understanding the irregular yield pattern of greenhouse-grown sweet peppers (Capsicum annuum L.) has been a challenge to researchers and greenhouse producers. Experimental data from 4 years, each consisting of 26 production weeks, were used in a time series analysis, neural network (NN) modeling, and regression analysis. Time series analysis revealed that weekly yield was influenced by yields from the preceding 2 weeks (Yd_1 and Yd_2), cumulative light 2 and 4 weeks prior (L_2 and L_4), and average 24-h air temperature 5 weeks prior (T_5). Cumulative light (L) data were transformed into kL by dividing by 1000 for subsequent NN modeling and regression analysis. These five inputs were used to establish a NN model, which illustrated the positive influence of Yd_1, kL_4, and kL_2 and negative influence of Yd_2 and T_5. Again, these five inputs were used in a regression analysis illustrating the positive influence of Yd_1 and the negative influence of Yd_2. Each input was further modified to include its squared value before entering the regression, which resulted in significant inputs of Yd_1, Yd_1 squared, and Yd_2 squared. Among these three analyses, the most consistent parameters were Yd_1 and Yd_2, confirming that the irregular yield pattern of greenhouse-grown peppers is of a biological nature. Environmental factors kL_2, kL_4, and T_5 did not show a consistent effect on yield in all three analyses, indicating yield pattern is less influenced by growing environment.
A xylem mutant (vse) was isolated from a Bambusa edulis (Odashima) Keng plantlet following vegetative micropropagation and subculture for 7 consecutive years and induced to proliferate in medium supplemented with 0.1 mg·L-1 (0.5 μm) thidiazuron (TDZ) and to develop roots in medium supplemented with 5 mg·L-1 (26.9 μm) α-naphthaleneacetic acid (NAA). Subsequent investigations comparing the growth habits of mutant plantlets with those of the wild type indicated that the growth of the former was retarded in a greenhouse. Several morphological abnormalities were observed in the vse mutant: it had thinner stems with fewer trichromes on the surface; the xylem vessels were smaller in diameter and contained crystal-like structures in the pith; the leaves were shorter and narrower with a sharp leaf blade angle; the roots were thinner and contained fewer xylem cells. The cation concentrations of both the mutant and wild type were similar in the in vitro analysis, except for those of iron and potassium, which were lower in mutant leaves in vivo. In 2-month-old mutant plants, iron chlorosis was observed on young leaves and a potassium deficiency was observed on older leaves. After 1 year of growth in the greenhouse, all of the wild-type plants had survived, but only 27% (16/60) of the mutant vse plants were alive.
Stem anatomy and modulus of elasticity (MOE) were compared between upright and trailing cultivars of periwinkle [Catharanthus roseus (G.) Don.]. The inheritance of growth habit and flower form was also studied. Internode cross sections revealed that phloem fiber was distributed at the inner cortex in upright cultivars but not in trailing cultivars. Except the youngest internode, the upright ‘Vitesse Pink’ had the highest MOE throughout the 1st–13th internodes above the cotyledon. The more trailing ‘Cora Cascade Strawberry’ had consistently lower MOE than a less trailing ‘Cora Cascade Polka Dot’. All F1 plants between upright and trailing cultivars were upright, and the F2 generation derived from self-pollinating F1 fit a 3 upright : 1 trailing segregation ratio. All F1 plants between upright/double-flower and trailing/single-flower exhibited upright and single-flowers, whereas plants in the F2 generation fitted a 9 upright/single-flower : 3 trailing/single-flower : 3 upright/double-flower : 1 trailing/double-flower ratio. New double-flowered periwinkle selections with trailing growth habit were successfully developed from the F2 population.
The chloroplast genome of an albino mutant isolated from tissue culture of the bamboo Bambusa edulis Munro was examined to identify aberrations. A number of the chloroplast genes encoding ATP synthases, photosystem II subunits, NADH dehydrogenase, and ribosomal proteins had been deleted, at least partially, in the albino mutant. Comparison of the two-dimensional electrophoresis profiles of albino and green bamboos revealed three spots of reduced intensity, indicating repression of these proteins in the albino mutants. Mass spectroscopic analysis subsequently revealed that two of these proteins are 33-kDa subunits of the photosystem II oxygen-evolving protein complex (PsbO) and one is a 23-kDa subunit of photosystem II oxygen-evolving protein complex (PsbP). The genes encoding these two proteins were cloned from B. edulis, and were denoted BePsbO (accession no. EF669513) and BePsbP (accession no. EF669512). Reverse transcription polymerase chain reaction and two-dimensional gel analyses of BePsbO and BePsbP in green and albino bamboos grown in the light or dark revealed that the albino mutant, similar to its green counterpart, sensed the light signal, resulting in the induction of BePsbO and BePsbP transcription, but it did not accumulate the protein products. We conclude that the repression of protein-expressing BePsbO and BePsbP is because of a defect in post-transcriptional regulation in the albino mutant.