diploids. That approach is time-consuming and technically difficult, especially for some woody species. Endosperm in angiosperms is naturally triploid and in vitro culture of endosperm explants has been used as a method for producing triploid plants
Chandra Thammina, Mingyang He, Litang Lu, Kaishuang Cao, Hao Yu, Yongqin Chen, Liangtao Tian, Junmei Chen, Richard McAvoy, Donna Ellis, Degang Zhao, Yuejin Wang, Xian Zhang, and Yi Li
Shujun Zhou, Guixue Zhou, and Kehu Li
endosperm or embryos were visible, so embryo sacs or embryos could be isolated ( Table 2 ). Thirty-eight seedlings were obtained from 23 fruits of 3 x × 2 x crosses and 96 seedlings from 20 fruits of 3 x × 4 x crosses ( Table 2 ). Only 090047 was not
Yuliya A. Salanenka, Martin C. Goffinet, and Alan G. Taylor
Cucumber is a species whose seeds have a semipermeable barrier restricting transport of solutes. A thin membrane beneath the testa, the perisperm–endosperm (PE) envelope, acts as a barrier to apoplastic permeability of cucumber and other
Douglas C. Doehlert, Tsung Min Kuo, John A. Juvik, Eric P. Beers, and Stanley H. Duke
Metabolic characteristics of developing sugary-l maize (Zea mays L.) endosperms were investigated. In the later stages of development (>30 days postpollination), sugary-1 kernels maintained higher levels of many enzyme activities and retained more moisture than normal kernels. Higher enzyme activities were attributed to moisture retention and were not associated with any increase in dry weight accumulation. Of enzyme activities measured at 20 days postpollination, that of ADP-glucose pyrophosphorylase was higher in sugary-1 kernels than in normal, whereas total amylase, a-amylase, and pullulanase activities were lower. Experiments testing the effects of zero, one, two, and three doses of the sugary-1 gene in OH43 endosperms indicated that the sugary-1 phenotype was not expressed until three doses of the sugary-1 gene were present. Decreased activities of amylases, but not of pullulanase, were attributed to an interference in detection by phytoglycogen. Increased ADP-glucose pyrophosphorylase activity is attributed to a response by the maize endosperm cells to increased sucrose concentrations.
Michael Olszewski, Wallace Pill, Thompson D. Pizzolato, and John Pesek
Germination studies indicated that increasing priming duration (-1.0 MPa at 20 °C for 7, 14, or 21 days) increased `Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex A.W. Hill] germination rate quadratically and seed moisture content linearly. A histological and anatomical study was conducted to identify and/or quantify principle mericarp organ or tissue volume changes influenced by priming duration. Embryo volume increased as priming duration increased from 7 to 21 days (0.014 to 0.034 mm3), and this was due more to radicle (0.007 to 0.022 mm3) than to cotyledon (0.006 to 0.011 mm3) growth. Concomitant with increased embryo volume was increased volume of the depleted layer (space formation, surrounding the embryo), from 0.038 after 7 days to 0.071 mm3 after 21 days, and increased hydrolysis of central endosperm (a thick-walled endosperm type). In nonprimed mericarps, central endosperm cells constituted 97% of the endosperm volume. The remaining 3% was comprised of 1% depleted layer and 2% distal endosperm (small, thin-walled, and irregularly shaped endosperm cells). During 7 or 21 days of priming, ≈10% or 40%, respectively, of central endosperm cells were hydrolyzed centrifugally around the embryo with a corresponding decrease in volume of central endosperm with thick cell walls. In addition, distal endosperm cells adjacent to the depleted layer, containing reserve materials, were digested of contents following 21 days priming, and sometimes, following 7 days priming. A long priming duration resulted in degradation of pericarp tissues, as indicated visually and by a decline in pericarp volume. We hypothesize that priming duration of parsley primarily influences radicle growth and centrifugal digestion and utilization of central and distal endosperm, resulting in a larger depleted layer required for embryo volume increases. Secondary events influenced by priming duration include cotyledon growth and degradation of pericarp tissues.
Marla K. Faver, Janice M. Coons, and John A. Juvik
Supersweet corn has problems establishing a stand, a problem that is related to a damaged pericarp that allows leakage from seeds during imbibition. This study compared seed vigor and sugar leakage of sweet corn isolines with different endosperms. Isoline pairs (C68, IaS125, Ia453, Il442a, and Oh43) of sweet corn (Zea mays L. var. rugosa) with two endosperms (sul or sh2) were used. Seeds were germinated at 10, 15, or 20C. Seeds also were planted in Urbana, Ill., where seedling growth was measured. Seeds also were soaked in water for 24 h, and then leachate was analyzed for sugars (anthrone method) and for sucrose, fructose, and glucose (HPLC). No seeds germinated at 10C. At 15 and 20C, more sul seeds germinated than sh2 seeds in most cases. In fields, sul plants were more vigorous than sh2 plants based on emergence, plant height, leaf number, weight, and leaf area. More sugars leaked from sh2 than sul seeds. More sucrose leaked from sh2 than sul seeds in all but two isolines, where none leaked. More fructose leaked from sh2 than sul seeds in all but two isolines, where no differences occurred. More glucose leaked from sh2 than sul seeds only in Oh43.
Tommy E. Thompson
Variability in soluble solids concentration (SSC, °Brix) in liquid endosperm (LE) among individual pecan [Carya illinoinensis (Wangenh.) K. Koch] fruits and among fruits from different trees and cultivars using a sugar refractometer was determined at College Station, Texas, in 1997. Repeatability of readings from LE from the same fruit was excellent. Fruits from the same tree did not vary for SSC, but significant differences among clones were common. Soluble solids concentration appears to decrease as the fruit matures. The SSC values for two full-sib clones (one susceptible to water split and one resistant to water split) were similar. This information discounts the possibility that high osmotic water potential gradients alone induce the water split phenomenon. A wide range of SSC percents was recorded. A low of 0.5% was recorded for LE from a `Houma' fruit, while 6.1% was recorded for LE from a fruit from a drought-stressed `Burkett' tree.
Anne C. Kurilich, Shyh-Shyan Wang, and John A. Juvik
Sucrose content at 21 DAP (typical maturity for harvesting) was observed to increase in the IL451b and IL678a backgrounds from zero to three doses of se1 by 65% and 18% respectively, indicating that this mutation varies in its expression in different genetic backgrounds. Associations between kernel phytoglycogen and starch content and se1 gene dosage are presented. The biochemical lesion associated with the se1 gene product is discussed.
Bernardo Ordás, Rosa A. Malvar, Amando Ordás, and Pedro Revilla
Baggett, 1977 ; Tracy, 1990 ). The maize kernel includes the pericarp, a maternal tissue, and the embryo, which are diploid, and the endosperm, which is triploid, having two doses of each gene coming from the female and one from the male ( Darrah et al
I.E. Yates and Darrell Sparks
Anatomy of normal and abortive fruit was compared at each of the three postpollination fruit drops characteristic of pecan [Carya illinoensis (Wangenh.) C. Koch]. Size differences between normal and abortive fruit decreased during the growing season, but differences in ovule size between normal and abortive fruit increased. During Drop II, normal and abortive fruit had an integument enclosing a massive nucellus in which an embryo sac was embedded, but embryo sac shape and constituents differed. Embryo sacs were distended in normal fruit and contained a definitive zygote as evidence of fertilization, i.e., union of egg and sperm. In contrast, embryo sacs in abortive fruit were shriveled and contained an egg apparatus as in unfertilized distillate flowers. During Drop III, normal and abortive fruit had a similar multicellular embryo. The nucellus in normal fruit was reduced to a cap at the micropyle region and cellular endosperm was evident. In contrast, the nucellus in abortive fruit was abundant and cellular endosperm was not evident. During Drop IV, embryo development in abortive fruit lagged behind that of normal fruit. Thus, we present the first direct evidence that aborted pecans deviate from normal fruit by an absence of a zygote at Drop II, a deficiency in cellular endosperm at Drop III, and a delay in embryo development at Drop IV.