Genetic Analysis of Bitter Principals in Momordica charantia Linn.

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Cucurbit Genetics Cooperative Report 17:129-131 (article 39) 1994

V.S. Devadas and Seemanthini Ramadas
College of Horticulture, Kerala Agricultural University, Vellanikkara, Trissur-680 645, India; Horticulture College and Research Institute, Tamil Nadu Agricultural University, Coimbatore-641 –3, India

Bitterness of bitter gourd (Momordica charantia Linn.) is due to presence of Momordicosides, which are glycosides of tetracyclic triterpinoids with a cucurbitane skeleton (1). The cucurbitane triterpenes have received attention because of their anticancer and other biological activities. Bitter form was reported to be dominant over mild bitter fruits (4), but detailed genetic studies on triterpinoid content of fruits are lacking.

The present study was conducted in the Tamil Nadu Agricultural University, Coimbatore, during 1991-92. Twelve morphologically and geographically diverse bitter gourd parents were analyzed for total triterpinoid content and the two highest (P7 and P12) and two lowest (P3 and P5) bitter parents were selected. The selected parents were MC 41 (P7), ‘White Long’ (P12), MC 13-Coimbatore Local (P3) and ‘Arka Harit’ (P5). Bitter principals of their hybrids and the parents recorded were analyzed in a 4 x 4 full diallel fashion using graphical and numerical methods (2, 3). Mean performance of the parents and hybrids for triterpinoid content are furnished in Table 1. Validity of the basic assumptions for a diallel experiment was found true in this experiment because t2 (1.16), deviation of b from zero (2.53), and that from unity (-0.51) were not statistically significant. The regression value, b, was 1.25 + 0.50.

The Vr-Wr graph for total triterpinoid content (Fig. 1) indicated over dominance gene action because the regression line intercepted the Y axis below the point of origin. Array points of three parents were located below the unit slope indicating predominance of additive gene action. Less bitter parents, P3 and P5, had maximum dominant alleles due to their position near the origin. The scattered position of the parental array points indicated the wide genetical diversity.

Numerical analysis indicated that variances due to D (additiveness) and H1 (dominance) components were statistically significant, their values being 4.06 +1.04 (at 1% level) and 7.99 + 3.09 (at 5% level). The magnitude of dominance was higher than additiveness. Variances due to F (1.81 + 2.67), H2 (-1.99 + 2.78), h2 (-O.15+ 1.89) and E (0.22 + 0.46) were not significant. Ratios of genetic parameters indicated overdominance ( √ H1/D = 1.40), unequal proportion of dominant genes over the recessive genes (KD.KR = 138), influence of one block of genes on the character (j2 /H2 = 0.08) and a high heritability (h2 n.s. = 0.97).

Graphic and numerical analyses indicated presence of overdominance, dominance and additive gene action. Hence a breeding program combining selection and hybridization (i.e., reciprocal recurrent selection) would be appropriate for the triterpinoid content of fruits.

This work is part of the Ph.D. thesis submitted by the first author to the Tamil Nadu Agricultural University, Coimbatoire, in 1993.

The first author is grateful to the Indian Council of Agricultural Research, New Delhi, for granting him a Senior Fellowship during the period of the study.

Table 1. Mean performance of the parents and hybrids for triterpinoid content of fruits (mg/g of triterpinoids on dry weight basis.

Female/Male

P3

P5

P7

P12
P3 0.9050 0.999 2.147 1.133
P5 6.333 1.262 0.929 2.314
P7 1.457 1.186 4.905 9.381
P12 3.038 4.195 2.081 4.376

SE = 0.461; CD (P = 0.05) = 1.332

Literature Cited

  1. Chandravadana, M.V.and M. Subhas Chander. 1990. Subcellular distribution of Momordicine II in Momordica charantia leaves. Indian J. Exp. Biol. 28:185-186.
  2. Hayman, B.I. 1954a. The analysis of variance of diallel crosses. Biometrics 10:235-244.
  3. Hayman, B.I. 1954b. The theory and analysis of diallel crosses. Genetics 39:789-809.
  4. Surio Babu, B. E. Reddy, and M.R. Rao. 1986. Inheritance of certain quantitative and qualitative characters in bitter gourd. South Indian Horticulture. 34(6):380-386.