Spatially regulated genes expressed during seed germination and postgerminative development are activated during embryogeny

Harada, John J.; Baden, Catherine S.; Comai, Lucio

doi:10.1007/bf00330851

Cited by 78 publications

(70 citation statements)

References 28 publications

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“…For example, Crouch and co-workers (8,(11)(12)(13) demonstrated that the levels of ABA and cruciferin mRNA peaked just before the onset of desiccation. Harada and coworkers similarly demonstrated increases in LEA.76 transcripts throughout the desiccation phase (16), and increases in ICL mRNA during the latter stages of desiccation (15). In the present study, seed in both the 70 and 55% moisture range contained little ABA and lacked LEA.76 and ICL transcripts.…”

Section: Germination Potentialsupporting

confidence: 64%

“…Previous studies (22,23) suggested that freezing may transiently predispose the seed to precocious germination, which is then inhibited by rapid desiccation. This was explored further in the present study by examining both ICL transcript levels and activity, because these have been shown to increase markedly during germination (6,10,15). The increase in transcript level may provide further proof of a transient alteration of developmental direction to germination, which is then inhibited by elevated ABA levels and rapid desiccation.…”

Section: Germination Potentialmentioning

confidence: 99%

“…This suggests that freezeinduced dehydration would also signal a switch and, as a consequence, normal seed development would be hastened. Harada and coworkers (6,15) have studied gene expression during embryogeny and germination in Brassica and have shown that transcripts such as those for ICL and malate synthase accumulate during the latter stages of embryogeny and could be used as defined markers of seed development.…”

mentioning

confidence: 99%

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Frost, Abscisic Acid, and Desiccation Hasten Embryo Development in Brassica napus

Johnson‐Flanagan

Huiwen²,

Geng³

et al. 1992

Plant Physiol.

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Seed development in canola (Brassica napus) following a mild nonlethal freeze was examined with respect to abscisic acid (ABA) levels, desiccation, and expression of LEA.76 and isocitrate lyase (ICL) transcripts. Plants with seed of 70 and 55% moisture contents were frozen to -50C for 3 hours, and seed development followed after thawing. In addition, similar processes were compared during induction of extreme desiccation tolerance by application of ABA in Brassica microspore-derived haploid embryos in culture. A mild freeze/thaw caused a premature switch in seed developmental direction from predesiccation to desiccation as indicated by an immediate and accelerated loss of seed moisture to levels similar to the mature seed in 7 instead of 35 days, and by elevated ABA levels and induction of low levels of LEA.76 and ICL transcripts. Similarly, addition of ABA to haploid embryos in culture resulted in the induction of desiccation tolerance and low levels of late embryogenesis-abundant (LEA) but not ICL transcripts. In contrast, normal seed development and desiccation of ABA-treated (desiccation-tolerant) embryos resulted in the induction of ICL and very high levels of LEA.76 transcripts. Similarly, desiccation of control (desiccation-sensitive) embryos resulted in very high levels of LEA.76 transcripts. These results indicate that although LEA-type proteins have been implicated in the development of desiccation tolerance, high transcript levels of LEA.76 were not observed in the induction of desiccation tolerance either by a hastening of the maturation process in the developing Brassica seed, or by the exogenous application of ABA to Brassica haploid embryos in culture.

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Section: Germination Potentialsupporting

confidence: 64%

Section: Germination Potentialmentioning

confidence: 99%

mentioning

confidence: 99%

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Frost, Abscisic Acid, and Desiccation Hasten Embryo Development in Brassica napus

Johnson‐Flanagan

Huiwen²,

Geng³

et al. 1992

Plant Physiol.

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“…Brassica napus L. (rapid-cycling base population, CrGC5) was grown as described previously (Harada et al, 1988). Tobacco (Nicotiana tabacum L. cv Samsun) was used for the plant transformation experiments.…”

Section: Plant Materiaismentioning

confidence: 99%

Isocitrate Lyase and Malate Synthase Genes from Brassica napus L. Are Active in Pollen

Zhang

Laudencia‐Chingcuanco

Comai

et al. 1994

Plant Physiol.

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To investigate if pollen possesses glyoxysomal function, we analyzed the activities of isocitrate lyase and malate synthase genes. Because the activities of these enzymes were exceedingly low in pollen extracts, we constructed fusion genes encoding j3-glucuronidase (CUS) that are regulated by isocitrate lyase or malate synthase promoters from Brassica napus L. to increase the sensitivity of our assays. Expression of the fusion genes in transgenic tobacco was qualitatively similar to that of the endogenous genes; CUS activity was low in dry seeds, maximal in seedlings, and very low or undetectable in leaves, indicating that the promoters are regulated correctly. We showed that isocitrate lyase and malate synthase genes are active at specific stages of pollen development and that their activities are not enhanced during pollen germination in transgenic tobacco. We also confirmed that the endogenous genes are active by showing that the corresponding mRNAs could be detected in pollen at specific stages of development. The activation of the isocitrate lyase and malate synthase genes suggests that glyoxysomal function is induced during pollen development.Glyoxysomes are specialized peroxisomes that play a pivotal role in the postgerminative growth of oilseed plants (Beevers, 1979;Huang et al., 1983;Trelease and Doman, 1984). These organelles contain the glyoxylate cycle and /3-oxidation enzymes that catalyze the net conversion of fatty acids into succinate and, thus, account for the ability of plants to utilize lipids as a carbon source for carbohydrate synthesis. The carbohydrates generated as a result of these reactions serve as nutrients for seedlings until they become photosynthetically active.Glyoxysomal function is induced at several stages of the plant life cycle when peroxisomes with different metabolic roles are converted into glyoxysomes. The induction of glyoxysomal function is generally monitored using two key glyoxylate cycle enzymes, isocitrate lyase and malate synthase, which are required for glyoxysomal function and are associated exclusively with glyoxysomes (reviewed by Olsen and

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“…Lipid and protein reserves are mobilized in the germinating seed to provide carbon and nitrogen for the seedling prior to the initiation of photosynthesis. Distinct mRNA populations are expressed in seedlings as compared to embryos and mature plants, but a number of genes expressed at high levels in seedlings are also represented in developing seeds (Harada et al, 1988;Hughes and Galau, 1988). Four genes, those encoding isocitrate lyase (IL) and malate synthase (MS) as well as two genes whose functions are unknown, are exemplary of germination and postgerminative gene expression programs.…”

Section: Germination Gene Expression Programsmentioning

confidence: 99%

Gene expression during plant embryogenesis and germination: an overview.

Thomas

1993

Plant Cell

229

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INTRODUCTIONSeed development represents a unique transition state in the life cycle of higher plants, providing the physical link between parenta1 and progeny sporophytic generations. During embrye genesis, the root and shoot apical meristems are specified, thus establishing the basic architecture of the seedling, and differentiation of vegetative tissue and organ systems occurs. Maturation events prepare the seed for germination and subsequent development of the mature plant. During maturation, the developing seed increases dramatically in volume and mass due to significant cell expansion and the concomitant accumulation and storage of protein and lipid to be used as nitrogen and carbon sources during germination. Early during the maturation phase, abscisic acid (ABA) levels reach a maximum, suppressing precocious germination and modulating gene expression. Desiccation ensures seed dormancy even in the absence of ABA and serves as the boundary between seed maturation and germination. Following imbibition, germination and seedling growth ensue, driven metabolically by the hydrolysis of protein and lipid stored during maturation.This review will provide an eclectic overview of gene expression in angiosperm embryogenesis and germination. I will focus primarily on dicot plants and will address only a small number of the more than 3 x 104 different genes expressed in embryos and seedlings. First, gene expression in early embryogenesis will be reviewed, focusing on selected results obtained with carrot somatic embryos. Control of gene expression during seed maturation will then be discussed, with an emphasis on cis-and tfans-acting factors involved in regulating maturation phase genes. A brief description of gene expression during germination and the relationship of embryonic and vegetative gene expression programs will follow. The review will conclude with a prospectus for the study of global gene expression patterns in early embryos. GENE EXPRESSION IN EARLY EMBRYOSAlthough most of the major discernible morphogenetic events in plants occur after germination, the overall architectural pattern of the mature plant is established during embryogenesis (see West and Harada, 1993, this issue). Following fertilization, an asymmetric division of the zygote of many dicots yields a basal cell that will produce the suspensor and an apical cellthe first embryonic cell. Ensuing cleavages of the apical cell yield a radially symmetric globular embryo with a differentiated protoderm, or dermatogen. Further cell divisions and subsequent morphogenesis break radial symmetry, yielding the bilaterally symmetric, heart stage embryo with root and shoot apices, incipient cotyledons, and provascular tissue (for recent reviews, se8 Meinke, 1991;Van Engelen and De Vries, 1992;De Jong et al., 1993a;West and Harada, 1993, this issue). So far, few genes have been identified that are expressed specifically during early embryogenesis, primarily because of technical difficulties associated with the mass ratios of the embryo and the surrounding mate...

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Spatially regulated genes expressed during seed germination and postgerminative development are activated during embryogeny

Cited by 78 publications

References 28 publications

Frost, Abscisic Acid, and Desiccation Hasten Embryo Development in Brassica napus

Frost, Abscisic Acid, and Desiccation Hasten Embryo Development in Brassica napus

Isocitrate Lyase and Malate Synthase Genes from Brassica napus L. Are Active in Pollen

Gene expression during plant embryogenesis and germination: an overview.

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