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Crystal macropatterns in Fagaceae and Nothofagaceae were examined from cleared herbarium leaves (eight genera, 122 spp.) by polarizing microscopy. Prisms and druses dominate, but previously undescribed intermediate forms occur in 25 species of Fagaceae. Sixty-two species had only prisms associated with vein orders 1–4, but smallest orders 5 and 6 had few or no crystals. In mesophyll, 98 species had small druses in spongy parenchyma and larger but fewer druses in palisade parenchyma. Subfamily Fagoideae conformed closely to this macropattern, Castaneoideae less so. Six Castaneoideae species lacked vein crystals. Two Fagoideae species and seven Nothofagus species lacked mesophyll crystals. Druses with prominent cores occur throughout Fagaceae but none were seen in Nothofagaceae. Tabular presentation of results shows significant although overlapping trends from Fagoideae to Castaneoideae to Nothofagaceae, with the latter taxon deviating most from Fagaceae. [ABSTRACT FROM AUTHOR]

Different sets of metastable states can be reached in glassy systems below some transition temperature depending on initial conditions and details of the dynamics. This is investigated for the Sherrington-Kirkpatrick spin glass model with long ranged interactions. In particular, the time dependent local field distribution and energy are calculated for zero temperature. This is done for a system quenched to zero temperature, slow cooling or simulated annealing, a greedy algorithm and repeated tapping. Results are obtained from Monte-Carlo simulations and a Master-Fokker-Planck approach. A comparison with replica symmetry broken theory, evaluated in high orders, shows that the energies obtained via dynamics are higher than the ground state energy of replica theory. Tapping and simulated annealing yield on the other hand results which are very close to the ground state energy. The local field distribution tends to zero for small fields. This is in contrast to the Edwards flat measure hypothesis. The distribution of energies obtained for different tapping strengths does again not follow the canonical form proposed by Edwards. [ABSTRACT FROM AUTHOR]

Tobacco floral nectaries undergo changes in form and function. As nectaries change from green to orange, a new pigment is expressed. Analysis demonstrated that it is β-carotene. Plastids undergo dramatic changes. Early in nectary development, they divide and by stage 9 (S9) they are engorged with starch. About S9, nectaries shift from quiescent anabolism to active catabolism resulting in starch breakdown and production of nectar sugars. Starch is replaced by osmiophilic bodies, which contain needle-like carotenoid crystals. Between S9 and S 12, amyloplasts are converted to chromoplasts. Changes in carotenoids and ascorbate were assayed and are expressed at low levels early in development; however, following S9 metabolic shift, syntheses of β-carotene and ascorbate greatly increase in advance of expression of nectar redox cycle. Transcript analysis for carotenoid and ascorbate biosynthetic pathways showed that these genes are significantly expressed at S6, prior to the S9 metabolic shift. Thus, formation of antioxidants β-carotene and ascorbate after the metabolic shift is independent of transcriptional regulation. We propose that biosynthesis of these antioxidants is governed by availability of substrate molecules that arise from starch breakdown. These processes and events may be amenable to molecular manipulation to provide a better system for insect attraction, cross pollination, and hybridization. [ABSTRACT FROM AUTHOR]

The first requirement to establish a successful hybrid soybean program is the availability of a stable male-sterile, female-fertile system. Male sterility has been an important tool in soybean breeding programs to improve traits such as yield, seed-protein and seed-oil content, and seed size. However, improvement of seed-set per se on male-sterile plants has not been an important breeding objective. The evaluation of the out-crossing potential of the available male-sterile, female-fertile soybean lines is crucial to determine the future of hybrid soybean. The objective of this study was to evaluate seed-set among 21 soybean lines segregating for male sterility at 10 different loci using Megachile rotundata as insect pollinator. Seed-set was evaluated in field conditions in 2001, 2002, and 2003 near Ames, Iowa. Our results indicated significant differences in seed-set among male-sterile lines. The effects of maturity group, pubescence color, the locus and/or the allele, and the genetic background of the lines segregating for male sterility were significant. Differences for seed-set among lines with independent mutational events at the same locus, (i.e. different alleles), also were significant. These results imply that interaction effects with the genetic background of the lines for traits related to fertility/sterility and insect-pollinator attraction and reward are important. Flower color had little effect on seed-set in the evaluated lines. The effect of year was very important on the performance of the lines for seed-set. This suggested that environmental conditions that favor plant–pollinator relationships need to be determined in order to increase insect-mediated cross-pollination to develop an efficient hybrid soybean program. [ABSTRACT FROM AUTHOR]

Presents a study which described the genetics and cytology of the genic male-sterile and female-sterile mutant. Materials and methods; Results; Discussion.

Focuses on the phenotypic expression of cells cultured from different regions of the intervertebral disc. Effects of culture methods on cells; Distinction between cells from different regions of the disc; Correlation between cells and articular cartilage.

Multicellular glandular trichomes form on gynoecia of wild annual Glycine species, annual soybean cultivars, and wild perennial Glycine species. These trichomes occur from the ovary base to the style base and, in perennial species, along the style as well. Trichomes form at least 2 d before anthesis, and new trichomes develop throughout flowering and also on young seed pods. Trichome structure is similar in all taxa examined, usually five to seven linearly arranged cells. Stalk cells with callose walls become highly vacuolate, and their cytoplasms have reduced numbers of Golgi bodies and endoplasmic reticulum. During secretion, two to four distal cells develop dense cytoplasms containing both prominent Golgi bodies with large vesicles and endoplasmic reticulum with enlarged lumens. Both organelles are involved in forming carbohydrate/protein secretory products. Internal secretion begins with products exuding between the plasmalemma and the primary wall of each distal cell. Secretion progresses between the primary wall and the outermost cuticle that entirely covers the trichome, which is thicker and more highly modified than a normal cuticle. This cuticle separates from cell walls in secretion regions. Products are exuded outside, occur on the inner surface of trichome and gynoecium, and are more obvious in perennial than in annual taxa. The composition and function of products are unknown. [ABSTRACT FROM AUTHOR]

We have characterized the major nectar protein (Nectarin I) from ornamental tobacco as a superoxide dismutase that functions to generate high levels of hydrogen peroxide in nectar. Other nectar functions include an anti-polygalacturonase activity that may be due to a polygalacturonase inhibiting protein (PGIP). We also examined the expression of defense related genes in the nectary gland by two independent methods. We isolated a sample of nectary-expressed cDNAs and found that 21% of these cDNAs were defense related clones. Finally, we examined the expression of a number of specific defense-related genes by hybridization to specific cDNAs. These results demonstrated that a number of specific defense genes were more strongly expressed in the floral nectary than in the foliage. Taken together these results indicate that the floral nectary gland can have specific functions in plant defense. [ABSTRACT FROM AUTHOR]