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The low molecular weight fraction of compounds released from immature wheat pistils supports barley pollen embryogenesis.

Lippmann R, Friedel S, Mock HP, Kumlehn J - Front Plant Sci (2015)

Bottom Line: Here, a micro-culture system was established to enable the culturing of populations of barley pollen at a density too low to allow unaided embryogenesis to occur, and this was then exploited to assess the effect of using various parts of the pistil as nurse tissue.The differential effect of various size classes of compounds present in the pistil-conditioned medium showed that the relevant molecule(s) was of molecular weight below 3 kDa.This work narrows down possible feeder molecules to lower molecular weight compounds and showed that the cellular origin of the active compound(s) is not specific to any tested part of the pistil.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Germany.

ABSTRACT
Pollen embryogenesis provides a useful means of generating haploid plants for plant breeding and basic research. Although it is well-established that the efficacy of the process can be enhanced by the provision of immature pistils as a nurse tissue, the origin and compound class of the signal molecule(s) involved is still elusive. Here, a micro-culture system was established to enable the culturing of populations of barley pollen at a density too low to allow unaided embryogenesis to occur, and this was then exploited to assess the effect of using various parts of the pistil as nurse tissue. A five-fold increase in the number of embryogenic calli formed was obtained by simply cutting the pistils in half. The effectiveness of the pistil-conditioned medium was transitory, since it needed replacement at least every 4 days to measurably ensure embryogenic development. The differential effect of various size classes of compounds present in the pistil-conditioned medium showed that the relevant molecule(s) was of molecular weight below 3 kDa. This work narrows down possible feeder molecules to lower molecular weight compounds and showed that the cellular origin of the active compound(s) is not specific to any tested part of the pistil. Furthermore, the increased recovery of calli during treatment with cut pistils may provide a useful tool for plant breeders and researchers using haploid technology in barley and other plant species.

No MeSH data available.


Related in: MedlinePlus

Reduction of possible feeder compounds using size exclusion. Embryogenic callus formation from populations of ca.150 immature pollen grains of cv. “Igri” supplemented at various intervals by (A) fresh pistil-preconditioned medium (intervals of medium exchange are given on the individual photographs recorded after 4 weeks of culture), (B) various size fractions of an extract of pistil-conditioned medium. A 4 day interval was sufficient to stimulate embryogenic development. The feeder effect is shown to be due to a compound(s) of size below the molecular weight cut-off of <3 kDa. MWCO: Molecular weight cut-off.
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Figure 5: Reduction of possible feeder compounds using size exclusion. Embryogenic callus formation from populations of ca.150 immature pollen grains of cv. “Igri” supplemented at various intervals by (A) fresh pistil-preconditioned medium (intervals of medium exchange are given on the individual photographs recorded after 4 weeks of culture), (B) various size fractions of an extract of pistil-conditioned medium. A 4 day interval was sufficient to stimulate embryogenic development. The feeder effect is shown to be due to a compound(s) of size below the molecular weight cut-off of <3 kDa. MWCO: Molecular weight cut-off.

Mentions: Pistil-preconditioned nutrient medium was only able to promote barley pollen embryogenesis when regularly refreshed. When an inductive medium was replaced only every 7 days, embryogenic development was not supported, whereas replacement every 4 days was effective (Figure 5A). As expected, however, embryogenic pollen development was much reduced as compared to continuous co-cultivation of bisected pistils. The composition of inductive medium was fractionated into two molecular size fractions, which were then added one by one to a non-inductive (low density, no nurse tissue) pollen culture. Stimulation of pollen embryogenesis was only induced by the presence of the smaller sized fraction which passed the molecular weight cut-off of ≤10 kDa. Further fractionation showed that the effect was due to a compound(s) of size below the molecular weight cut-off of ≤3 kDa (Figure 5B). The stimulatory effect of adding this size-fraction was lower than that directly provided by the cut pistils, conditioned medium or the ≤10 kDa fraction, which can be attributed to the expected loss of a substantial proportion of the effective signal molecules owing to the fractionation procedure.


The low molecular weight fraction of compounds released from immature wheat pistils supports barley pollen embryogenesis.

Lippmann R, Friedel S, Mock HP, Kumlehn J - Front Plant Sci (2015)

Reduction of possible feeder compounds using size exclusion. Embryogenic callus formation from populations of ca.150 immature pollen grains of cv. “Igri” supplemented at various intervals by (A) fresh pistil-preconditioned medium (intervals of medium exchange are given on the individual photographs recorded after 4 weeks of culture), (B) various size fractions of an extract of pistil-conditioned medium. A 4 day interval was sufficient to stimulate embryogenic development. The feeder effect is shown to be due to a compound(s) of size below the molecular weight cut-off of <3 kDa. MWCO: Molecular weight cut-off.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493395&req=5

Figure 5: Reduction of possible feeder compounds using size exclusion. Embryogenic callus formation from populations of ca.150 immature pollen grains of cv. “Igri” supplemented at various intervals by (A) fresh pistil-preconditioned medium (intervals of medium exchange are given on the individual photographs recorded after 4 weeks of culture), (B) various size fractions of an extract of pistil-conditioned medium. A 4 day interval was sufficient to stimulate embryogenic development. The feeder effect is shown to be due to a compound(s) of size below the molecular weight cut-off of <3 kDa. MWCO: Molecular weight cut-off.
Mentions: Pistil-preconditioned nutrient medium was only able to promote barley pollen embryogenesis when regularly refreshed. When an inductive medium was replaced only every 7 days, embryogenic development was not supported, whereas replacement every 4 days was effective (Figure 5A). As expected, however, embryogenic pollen development was much reduced as compared to continuous co-cultivation of bisected pistils. The composition of inductive medium was fractionated into two molecular size fractions, which were then added one by one to a non-inductive (low density, no nurse tissue) pollen culture. Stimulation of pollen embryogenesis was only induced by the presence of the smaller sized fraction which passed the molecular weight cut-off of ≤10 kDa. Further fractionation showed that the effect was due to a compound(s) of size below the molecular weight cut-off of ≤3 kDa (Figure 5B). The stimulatory effect of adding this size-fraction was lower than that directly provided by the cut pistils, conditioned medium or the ≤10 kDa fraction, which can be attributed to the expected loss of a substantial proportion of the effective signal molecules owing to the fractionation procedure.

Bottom Line: Here, a micro-culture system was established to enable the culturing of populations of barley pollen at a density too low to allow unaided embryogenesis to occur, and this was then exploited to assess the effect of using various parts of the pistil as nurse tissue.The differential effect of various size classes of compounds present in the pistil-conditioned medium showed that the relevant molecule(s) was of molecular weight below 3 kDa.This work narrows down possible feeder molecules to lower molecular weight compounds and showed that the cellular origin of the active compound(s) is not specific to any tested part of the pistil.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Germany.

ABSTRACT
Pollen embryogenesis provides a useful means of generating haploid plants for plant breeding and basic research. Although it is well-established that the efficacy of the process can be enhanced by the provision of immature pistils as a nurse tissue, the origin and compound class of the signal molecule(s) involved is still elusive. Here, a micro-culture system was established to enable the culturing of populations of barley pollen at a density too low to allow unaided embryogenesis to occur, and this was then exploited to assess the effect of using various parts of the pistil as nurse tissue. A five-fold increase in the number of embryogenic calli formed was obtained by simply cutting the pistils in half. The effectiveness of the pistil-conditioned medium was transitory, since it needed replacement at least every 4 days to measurably ensure embryogenic development. The differential effect of various size classes of compounds present in the pistil-conditioned medium showed that the relevant molecule(s) was of molecular weight below 3 kDa. This work narrows down possible feeder molecules to lower molecular weight compounds and showed that the cellular origin of the active compound(s) is not specific to any tested part of the pistil. Furthermore, the increased recovery of calli during treatment with cut pistils may provide a useful tool for plant breeders and researchers using haploid technology in barley and other plant species.

No MeSH data available.


Related in: MedlinePlus