Bakanae is now easily prevented
by treatment of seeds with fungicides prior to sowing. The first
paper on the cause of bakanae was published in 1898 by Shotaro Hori
who demonstrated that the symptoms were induced by infection with
a fungus belonging to the genus Fusarium, probably Fusarium heterosporium
Characteristic elongated rice seedling caused by bakanae
In 1912, Sawada published
a paper in the Formosan Agricultural Review entitled "The Diseases
of Crops in Taiwan" in which he suggested that the elongation
in rice seedlings infected with bakanae fungus might be due to a
stimulus derived from fungal hyphae.
Subsequently, Eiichi Kurosawa
(1926) found that culture filtrates from dried rice seedlings caused
marked elongation in rice and other sub-tropical grasses. He concluded
that bakanae fungus secretes a chemical that stimulates shoot elongation,
inhibits chlorophyll formation and suppresses root growth.
Although there has been controversy
among plant pathologists over the nomenclature of bakanae fungus,
in the 1930s, the imperfect stage of the fungus was named Fusarium
moniliforme (Sheldon) and the perfect stage, Gibberella fujikuroi
(Saw.) Wr. by H.W. Wollenweber. The terms "Fujikuroi"
and "Saw." in Gibberella fujikuroi (Saw.) Wr. were derived
from the names of two distinguished Japanese plant pathologists,
Yosaburo Fujikuro and Kenkichi Sawada.
Teijiro Yabuta initiated work
on the isolation of the active component using the fungal strains
provided by Kurosawa. In 1934, Yabuta isolated a crystalline compound
from the fungal culture filtrate that inhibited growth of rice seedlings
at all concentrations tested. The structure of the inhibitor was
shown to be 5-n-butylpicolinic acid or fusaric acid. The formation
of fusaric acid in culture filtrates was suppressed by changing
the composition of the culture medium. As a result, a non-crystalline
solid was obtained from the culture filtrate that stimulated the
growth of rice seedlings. This compound was named gibberellin by
Yabuta in 1935; the first use of the term "gibberellin"
in the scientific literature.
In 1938, Yabuta and his associate
Yusuke Sumiki finally succeeded in crystallizing a pale yellow solid
to yield gibberellin A and gibberellin B (The names were subsequently
interchanged in 1941 and the original gibberellin A was found to
be inactive.) Determination of the structure of the active gibberellin
was hampered by a shortage of pure crystalline sample. By current
standards the productivity of their fungal strain was extremely
poor and they did not know that their sample of gibberellin A was
not pure, but a mixture of structurally-related gibberellins.
In the United States, the first
research on gibberellins began after the Second World War by a research
unit at Camp Dietrick, Maryland. In 1950, John E. Mitchell reported
optimal fermentation procedures for the fungus, as well as the effects
of fungal extracts on the growth of bean (Vicia faba)seedlings(Mitchell
& Angel 1951). Work also began at the Northern USDA Regional
Research Laboratories in Peoria, Illinois in the USA using the strain
provided by Mitchell. Large scale fermentations were carried out
with the purpose of producing pure gibberellin A for agricultural
uses but initial fermentations were inactive.
In 1951, Sumiki visited the
United States and met Frank H. Stodola. After returning to Japan
he sent new cultures to the USA but these also proved inactive.
The problem was traced to the lack of magnesium in the culture medium
and good yields of gibberellin were obtained when the culture medium
was supplemented with magnesium sulphate. The physical properties
of gibberellin isolated from these fermentations were found to be
surprisingly different from those reported by the Japanese and the
new compound was named gibberellin-x. (Stodola et al., 1955).
At about the same time in the
UK, a team of researchers ( Philip Curtis, Brian Cross, John Grove,
Jake MacMillan and Paddy Mulholland) at Akers Research Laboratories
(ICI) isolated a new gibberellin which was given the name "gibberellic
acid".This compound had physical properties different from
the Japanese gibberellin A(Curtis & Cross, 1954). Samples were
exchanged between Stodola and Grove and "gibberellic acid"
and gibberellin-X were found to have identical chemical and physical
properties and the name gibberellic acid was accepted by both groups.
A structure for gibberellic acid was proposed in 1956 but later
revised see Grove 1961.
In 1955, members of Sumuki
group, (Takahashi et al.) succeeded in separating the methyl ester
of gibberellin A into three components, from which corresponding
free acids were obtained and named gibberellins A1, A2, and A3.
Gibberellin A3 was found to be identical to gibberellic acid. In
1957, Takahashi et al. isolated a new gibberellin named gibberellin
A4 as a minor component from the culture filtrate.
In the mid 1950s, evidence
that gibberellins were naturally occurring substances in higher
plants began to appear in the literature. Using techniques that
had been used to isolate gibberellins from the fungus, Margaret
Radley at ICI in the UK demonstrated the presence of gibberellin-like
substances in higher plants. In the USA, the first reports of a
gibberellin-like substance in maize came from Bernard Phinney et
al using dwarf maize mutants to assay for activity in plant extracts.
This was followed by the isolation of crystalline gibberellin A1,
A5, A6 and A8 from runner bean (Phaseolus multiflorus) (MacMillan
et al. 1958, 1959, 1960,1962). The original samples from these isolations
are now on display at Long Ashton.
In the 1960s the number of
gibberellins reported in the literature isolated from fungal and
plant origins rapidly increased. In 1968, J. MacMillan & N.
Takahashi reached an agreement that all gibberellins should be assigned
numbers as gibberellin A1-x, irrespective of their origin. Over
the past 20 years using modern analytical techniques many more gibberellins
have been identified. At the present time the current number of
gibberellins identified is 126.
For a more detailed description
of the history of gibberellins please see Phinney, B.O.(1983) and
Tamura, S. (1990)
Curtis PJ, Cross BE. 1954. Gibberellic acid. A new metabolite from
the culture filtrates of Gibberella fujikuroi. Chem. Ind. 1066.
Grove JF. 1961. The gibberellins. Quart. rev (Chem. Soc. London) 15,
Hori S. 1898. Some observations
on "Bakanae" disease of the rice plant. Mem. Agric. Res.
Sta. (Tokyo) 12 (1),110-119.
Kurosawa E. 1926.Experimental
studies on the nature of the substance secreted by the "bakanae"
fungus. Nat HistSoc Formosa. 16, 213-227.
Macmillan J, Suter PJ. 1958.
The occurence of gibberellin A1 in higher plants: Isolation from
the seed of runner bean (Phaseolus multiflorus). Naturwiss 45, 46.
Macmillan J, Seaton JC, Suter
PJ. 1959. A new plant-growth promoting acid-gibberellin A5 from
the seed of Phaseolus multiflorus. Proc. Chem. Soc. 325.
Macmillan J, Seaton JC, Suter
PJ. 1960. Isolation of gibberellin A1 and gibberellin A5 from<
i>Phaseolus multiflorus. Tetrahedron. 11, 60-66.
Macmillan J, Seaton JC, Suter
PJ. 1962. Isolation and structures of gibberellin A6 and gibberellin
A8. Tetrahedron. 18, 349-355.
MacMillan J, Takahashi N. 1968.
Proposed procedure for the allocation of trivial names to the gibberellins.
Nature. 217. 170-171.
Mitchell JE, Angel CR. 1951.The
growth-stimulating properties of a metabolic product of Fusarium
Phinney BO. 1983 The history
of gibberellins. In: The Biochemistry and Physiology of Gibberellins
(Ed. Crozier A.) vol 1. pp 19-52. Praeger Publishers USA.
Phinney BO, West CA, Ritzel
MB, Neely PM. 1957. Evidence for gibberellin-like substances from
flowering plants. Proc. Nat. Acad. Sci. (U.S.A.) 43. 398-404
Radley M. 1956. Occurrence
of substances similar to gibberellic acid in higher plants. Nature
Stodola FH, Raper KB, Fennell
DI, Conway HF, Johns VE, Langford CT, Jackson RW. 1955. The microbial
production of gibberellins A and X. Arch. Biochem. Biophys. 54,
Takahashi N, Kitamura H, Kawarada
A, Seta Y, Takai M, Tamura S, Sumiki Y. 1955. Isolation of gibberellins
and their properties. Bull Agric Chem Soc Japan. 19. 267-277.
Takahashi N, Seta Y, Kitamura
H, Sumiki Y. 1957. A new gibberellin, gibberellin A4. Bull Agric
Chem Soc Japan. 21. 396-398.
Tamura, S. 1990. Historical
aspects of gibberellins. In: Gibberellins ( Eds Takahashi N, Phinney
BO and Macmillan J) pp 1-8,Springer-Verlag New York.
Yabuta T, Sumiki Y. 1938. On the crystal of gibberellin, a substance
to promote plant growth. J Agric Chem Soc Japan. 14. 1526.