Dendrobium orchids carrying antisense ACC oxidase: small changes in flower morphology and a delay of bud abortion,flower senescence,and abscission of flowers

Transgenic Research - Four Dendrobium Sonia ‘Earsakul’ lines were generated by insertion of one, two or three antisense copies of a Carica papaya gene encoding...     

New microsatellite markers isolated from mungbean (Vigna radiata (L.) Wilczek)

In this study, we reported the isolation and analysis of new polymorphic microsatellites in mungbean (Vigna radiata (L.) Wilczek). Twelve out of 210 primer pairs screened in 30 mungbean accessions gave polymorphism. The polymorphic markers detected two to three alleles per locus with an average of 2.08. Observed heterozygosity varied from 0 to 0.133, while expected heterozygosity ranged from 0.095 to 0.498. Tests for Hardy-Weinberg equilibrium (HWE) and pairwise linkage disequilibrium of the polymorphic loci revealed that all loci except MB-SSR14 significantly departed from HWE and four pairwise combinations, viz. MB-SSR14 vs. MB-SSR42, MB-SSR42 vs. MB-SSR87, MB-SSR114 vs. MB-SSR121, and MB-SSR175 vs. MB-SSR231 significantly deviated from linkage disequilibrium. The markers are being used to study genetic diversity and genome mapping of mungbean.     

Soluble carbohydrate content of soybean [Glycine max (L.) merr.] somatic and zygotic embryos during development

Summary Somatic and zygotic embryos of soybean cv. Jack were analyzed for soluble carbohydrate, total lipids, and protein during development. Zygotic embryos accumulated trace amounts of fructose, galactose, and galactinol., whereas somatic embryos contained only trace amounts of galactose. Somatic embryos accumulated much higher glucose levels than zygotic embryos. Both somatic and zygotic embryos contain low levels of sucrose, myoinositol, and pinitol. Raffinose and stachyose accumulated in the late developmental stages of zygotic embryos, but only stachyose was found to accumulate in the late stage somatic embryos. Zygotic embryos contained low total lipid levels up to 50 d after flowering (DAF) and then the levels increased to 16% by 55 DAF and 21% at 65 DAF. Somatic embryos had low levels of total lipids throughout development with the maximum of only 4.7%. Soybean zygotic embryos contained about 40% protein throughout development, while the protein concentration of somatic embryos decreased from 44% to 25% as maturation approached. These studies demonstrate that the composition of Jack zygotic embryos is similar to that described for other cultivars during development while the somatic embryo composition and size is markedly different. The low somatic embryo germination often noted might be due to the abnormal development as shown by a composition different from that of mature zygotic embryos. The low concentration of the raffinose series sugars might be especially important factors.     

Inheritance of resistance to iron deficiency and identification of AFLP markers associated with the resistance in mungbean (Vigna radiata (L.) Wilczek)

Iron deficiency chlorosis (IDC) is a major problem reducing yield of mungbean in many countries. In this study, we crossed “KPS1”, the most popular Thai mungbean cultivar susceptible to IDC with “NM10-12”, a mungbean line from Pakistan resistant to IDC. Segregation analysis of the F₂ population revealed that the resistance is controlled by a major gene (IR) with dominant effect. Two AFLP markers, E-ACT/M-CTA and E-ACC/M-CTG were identified closely linking with the IR gene. The frequencies of these markers were assessed in 241 mungbean accessions from several countries. The accessions could be divided, in relative to total chlorophyll content of the resistant check (NM10-12) and the susceptible check (KPS1), into the resistant group with 125 accessions and the susceptible group with 116 accessions. Among 125 resistant accessions, E-ACT/M-CTA and E-ACC/M-CTG were present in 119 (95%) and 109 (87%) accessions, respectively. Both markers can identify all resistant accessions from England, Indonesia and Pakistan, but only E-ACT/M-CTA linked to all resistant accessions from Australia, India, Iraq, Taiwan and Thailand. Understanding the inheritance and identifying molecular markers linking to the IR gene can help plant breeders to improve this crop for growing in iron-deficient soils.     

EMS-induced mutation followed by quizalofop-screening increased lipid productivity in Chlorella sp.

Bioprocess and Biosystems Engineering - The objective of this study was to enhance biomass and lipid productivity in Chlorella sp. isolate 6-4 by inducing mutagenesis with two growth inhibitors:...     

Prevention of pink-pigmented methylotrophic bacteria (Methylohacterium mesophilicum) contamination of plant tissue cultures

Pink-pigmented facultative methylotrophic bacteria (PPFMs) have been found on the surfaces of leaves of most plants tested. We found PPFMs on the leaf surfaces of all 40 plants (38 species) tested and on soybean pods by pressing onto AMS medium with methanol as the sole carbon source. The abundance ranged from 0.5 colony forming unit (cfu) /cm² to 69.4 cfu/cm² on the leaf surfaces. PPFMs were found in homogenized leaf tissues of only 4 of the species after surface disinfestation with 1.05% sodium hypochlorite and were rarely found in cultures initiated from surface disinfested Datura innoxia leaves or inside surface disinfested soybean pods. Of 20 antibiotics tested for PPFM growth inhibition, rifampicin was the most effective and of seven others which also inhibited PPFM growth, cefotaxime should be the most useful due to the expected low plant cell toxicity. These antibiotics could be used in concert with common surface sterilization procedures to prevent the introduction or to eliminate PPFM bacteria in tissue cultures. Thus, while PPFMs are present on the surfaces of most plant tissues, surface disinfestation alone can effectively remove them so that uncontaminated tissue cultures can be initiated in most cases.