ASCORBIC ACID AND FUSARIUM-WILT
IN LINSEED
BY J. G. BHATT Institute of Plant Industry, Indore*
AscoRBIC ACID has been variously claimed to play a considerable role in disease resistance. The relation of yellows and mosaic resistance to high ascorbic acid content in cabbage has been reported by Walker (1944). Kalyanasundaram (1942, 1952) investigating the host parasite response to fusarium-wilt in cotton and red gram found a reduction in ascorbic acid content in leaves and an increase in reducing sugars during wilt. He also observed that the resistant cotton varieties had signifi-cantly more ascorbic acid than the susceptible varieties. Similar was the case with carbohydrate contents. lt was concluded that these high energy yielding substances are favourably utilised in the resistant plants for the formation of a labile toxic substance inhibiting the pathogen. Further work by Kalyanasundaram (1954), indicated that resistance acquired by the wilt susceptible cotton plants given zinc nutrition was probably due to their increased ascorbic acid and carbohydrate con-tents. Working on the Fusarium wilt oflinseed, Bhatt (1956) confirmed that ascorbic acid decreased with advancing wilt symptoms. Pilgrim and Futrell (1957) found no consistent correlation between ascorbic acid concentration and resistance to stem rust in different susceptible and resistant wheat varieties.
The objects of the present experiment were (1) to see if increase in internal concentration of ascorbic acid increased resistance to Fusarium wilt and (2) to examine the ascorbic acid contents of a number of linseed varieties.
MATERIAL AND METHODS
Resi$tant and susceptible varieties of linseed were obtained from U.P. Indian Agricultural Research Institute, New Delhi and West Bengal. The~ we~e grown in ea~thern po~s containing ~terilis~d fi.eld soil. Ascorbic acid was determmed by Indophenol VIsual titration method of Bessey and King (1933). When ascorbic acid was applied artificially, the highly wilt susceptible variety IPI-6 was used. Deter-minations were made in duplicate and the mean values are given in the following tables.
Five-week old, linseed plants were selected for uniformity and cut under water to remove the root system. The treatments given in
ASCORBIC ACID AND FUSARIUM-WILT IN LINSEED
61
cate were ( 1) control,
(2) A-20
mg ascorbic acid and(3) B-20
mg. ascorbic acid. Plants were transferred to conical flasks each contain-ing 20 mg. of ascorbic acid dissolved in 100 mi. of distilled water and allowed to absorb the solution for six hours. The control plants were put in the same quan1ity of distilled water. Thereafter the plants were taken out, put in flasks containing distilled water and inoculated with equal quantities of uniform suspension of the mycelial mats of Fusarium lini. The contents of 1he flasks were changed twice daily to prevent developmen1 of the contaminants.EXPERIMENTAL RESULTS
The quantity of ascorbic acid absorbed by the cut shoots was cal-cula1ed from the quan1ity left over after absorption after six hours. The mean values of ascorbic acid absorbed under the two treatments are given in Table I.
TABLE I
Quantity of Quantity of No Treatment ascorbic acid ascorbic acid
left absorbed
--~-·--- - - - ·
mg mg
A
4·50
15·50
2B
4·66
15·34
Linseed plants thus absorbed considerable quantities of ascorbic acid. Symptoms of wilt appeared
60
hours after inoculation in ascorbic acid-treated plants. No wilting occurred in the infected control plants at this stage, and it took about48
hours more for the wilt to appear. When complete drooping of the terminal portions and the leaves was noticed in the treated plants they were removed along with the infected control plants and the leaves and stem portions analysed for their ascorbic acid content.TABLE II
Ascorbic acid in mg per
100
gm fresh weightTreatment Leaf Stem Total
Infected control
55·50
36·07
91· 57
A
111·00
36·07
147·07
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BHATTThe application of ascorbic acid hastened the appearance of wilt and an appreciable amount of ascorbic acid remained in the treated plants after wilting occurred. A higher ascorbic acid content apparently increased the susceptibility of the plants to disease. The ascorbic acid content of several wilt susceptible and wilt-resistant linseed varieties was also determined.
TABLE III
Ascorbic acid in mg per
100
gm fresh weightNo. Variety Leaf Stem Root Total
Resistant Varieties
NP-495
91· 840
32·480
3·360
127·680
2
NP-500
94·080
38·080
3·920
136·080
3
H-81
78·400
39·200
2·240
119;840
4
H-437
85. 120
39·200
2·240
126·560
5
WB-31
73·595
45·920
2·240
121·755
6
WB-37
61· 305
42·560
3·360
107·225
Mean
80·723
39·573
2·893
123· 190
S uscepti bl e Varieties
I
NP-498
LOS·280
43·680
2·240
151·200
2
NP-489
89·800
31· 360
2·240
123·400
3
H-421
76·160
45·920
3 ·360
125·440
4
H-425
99·240
42·311
3·360
144·911
5
WB-95
87· 360
39·200
2·240
128·800
6
WB-96
123·200
47·040
3·360
173·600
Mean
96· 840
41·585
2·800
141·225
The data in Table III show that there was no significant difference between the ascorbic acid contents of the resistant and susceptible varieties. On an average susceptible varieties contained slightly more ascorbic acid than the resistant varieties. The wilt-susceptible variety
ASCORBIC ACID AND FUSARIUM-WiLT IN LINSEED
63
DISCUSSION
It appeared that the part played by ascorbic acid in wilt resistance was rather uncertain. Results obtained by different workers on different plants do not-present a consistent picture of its metabolic activity. Kalyanasundaram's (1955) observation that wilt resistant cotton varieties contained more ascorbic acid than the wilt-susceptible varieties does not hold good in the case of linseed varieties. In this connection it should be noted that working on the physiological aspects of tetraploidy in cabbage, Barr and Newcomer (1943), found that tetraploid plants contained more ascorbic acid than the diploid ones. Similarly Sullivan and Myers (1939) reported higher reducing sugar and carbohydrate contents in tetraploid Lolium than the diploid. Thus high ascorbic acid and carbohydrate content found by Kalyana-sundaram (I 955) in wilt-resistant hirsutum cotton varieties as against wilt-susceptible arboreum cotton varieties appears to be more of a varietal difference in the two different species of cotton, which is perhaps not related to resistance to wilt.
That high ascorbic acid content is not a criterion for disease resis-tance can be seen from the work of Pilgrim and Futrell (1957) on several varieties of wheat. They noticed that rusted plants of Wisconsin-245 and Hope contained more ascorbic acid than did non-rusted ones, whereas the almost resistant variety Nugget contained less. Therefore even if ascorbic acid is increased by growing plants on trace element amended soils its role in disease resistance is doubtful.
SUMMARY
No relation was found between ascorbic acid content and fusarium-. wilt in linseed. The susceptible variety did not show increased resis-tance to wilt when artificially supplied with ascorbic acid, and on the contrary became more susceptible. There were no significant differ-ences between the ascorbic acid contents of several wilt-susceptible and wilt-resistant linseed varieties obtained from different parts of India.
ACKNOWLEDGEMENT
Grateful thanks of the author are due to the late Prof. R. H. Dastur for kindly going through the manuscript.
REFERENCES
1. BA~R, C. G. AND NEWC:OMER, E. H. (1943). Physiological aspects of tetra 'loidy
m cabbage. J. Agnc. Res., 61, 329-36. ·
2. BESSEY, O._A. A~D KING,
c:;.
G. (193~). _The distribution of vitamin C in plant and ammal tissues and rts determmatron. J. Bioi. Chem., 103, 687.3. BHATT, J. G. (1956). The relation of ascorbic acid to Fusarium-wilt in linseed.
64
4. KALYANASUNDARAM, R. (1952). Ascorbic acid and Fusarium-wilted plants. Proc. Indian Acad. Sci., 36 B, 102-04.
5. - - - - (1954). Soil conditions and root diseases-XU. The role of zinc and manganese in altering host metabolism. J. Indian Bot. Soc., 33, 197-202.
6. - - - - (1955). Soil conditions and root diseases-XIV. Host-parasite res-ponse to Fusarium-wilt. Proc. Indian Acad. Sci., 42 B, 145-53.
7. PILGRIM, A. J. AND FUTRELL, M. C. (1957). The ascorbic acid content at different stages of growth of stem rust susceptible and resistant wheat grown under different conditions. Phytopath., 47, 193-96.
8. SuLLIVAN, J. T. AND MYERS, W. M. (1939). Chemical composition of diploid and tetraploid Lolium perenne L. J. Amer. Soc. Agron., 31, 869-71.