Knowledge Nugget | India’s mustard crop is facing a serious ‘hidden threat’. What is it?

3. It is generally sown from mid- to late-October and harvested after 130-150 days. The mustard crop’s growing susceptibility to Orobanche and other pathogens – pests (especially aphids) and fungal diseases (white rust, leaf blight, stem rot and powdery mildew) – is, hence, a matter of concern.

Orobanche

1. Orobanche aegyptiaca is a parasitic weed that attaches to the roots of mustard plants and extracts nutrients, carbon and water from them. By depriving the host crop of these, it causes wilting, yellowing and stunted growth of the plants and, thereby, lower mustard seed yields.

Orobanche weed plant from a mustard field in Haryana’s Sirsa district. (Image: Special arrangement)

2. According to Bhagirath Choudhary, director of the Jodhpur (Rajasthan)-based South Asia Biotechnology Centre (SABC), Orobanche has become the “No. 1 hidden threat” in the major mustard-growing areas of Haryana and Rajasthan.

3. The “hidden” threat is due to the weed’s underground location and its establishing connection with the host plant’s roots to steal nutrients and water. By the time the parasite’s shoots appear above the ground and become visible, the damage to the crop from diversion and undernourishment would have already occurred.

4. A single Orobanche shoot produces 40-45 purple-coloured flowers, each further containing 4,000-5,000 very minute seeds. These remain viable in the soil for up to 20 years and disperse by wind and water to other fields. Once a strong seed bank is built, it creates conditions for rapid infestation. Farmers usually give the first irrigation for mustard 25-30 days after sowing. The soil moisture from that is, however, also conducive for the germination of the Orobanche seeds, followed immediately by their underground establishment and attachment to the mustard plant roots.

BEYOND THE NUGGET: Mustard hybrid DMH-11

Given mustard’s importance as an oilseed and the growing threat from weeds, India’s policymakers would have take a considered decision on allowing GM breeding and crop cultivation. And it will have to be based more on science and farm economics than ideology. Thus, let’s know about the GM Mustard. 

1. The transgenic mustard hybrid DMH-11 has been developed by the Centre for Genetic Manipulation of Crop Plants (CGMCP) at Delhi University.

2. Hybridisation involves crossing two genetically dissimilar plant varieties that can even be from the same species. The first-generation (F1) offspring from such crosses tend to have higher yields than what either parent can individually give.

3. Such hybridisation isn’t easy in mustard, as its flowers have both female (pistil) and male (stamen) reproductive organs, making the plants largely self-pollinating. Since the eggs of one plant cannot be fertilised by the pollen grains from another, it limits the scope for developing hybrids — unlike in cotton, maize or tomato, where this can be done through simple emasculation or physical removal of anthers.

4. By genetic modification (GM). Scientists at Delhi University’s Centre for Genetic Manipulation of Crop Plants (CGMCP) have developed the hybrid mustard DMH-11 containing two alien genes isolated from a soil bacterium called Bacillus amyloliquefaciens.

5. The first gene (‘barnase’) codes for a protein that impairs pollen production and renders the plant into which it is incorporated male-sterile. This plant is then crossed with a fertile parental line containing, in turn, the second ‘barstar’ gene that blocks the action of the barnase gene. The resultant F1 progeny is both high-yielding and also capable of producing seed/ grain, thanks to the barstar gene in the second fertile line.

6. The CGMCP scientists have deployed the barnase-barstar GM technology to create what they say is a robust and viable hybridisation system in mustard. This system was used to develop DMH-11 by crossing a popular Indian mustard variety ‘Varuna’ (the barnase line) with an East European ‘Early Heera-2’ mutant (barstar). DMH-11 is claimed to have shown an average 28% yield increase over Varuna in contained field trials carried out by the Indian Council of Agricultural Research (ICAR).

Post Read Questions

(1) Consider the following statements:

1. Mustard is India’s biggest edible oil-yielding crop.

2. Mustard flowers have both female (pistil) and male (stamen) reproductive organs.

3. The Genetic Engineering Appraisal Committee is the regulator for introduction of any GM material. 

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

(2) Other than resistance to pests, what are the prospects for which genetically engineered plants have been created? (UPSC CSE 2012)

1. To enable them to withstand drought

2. To increase the nutritive value of the produce

3. To enable them to grow and do photosynthesis in spaceships and space stations

4. To increase their shelf life

Select the correct answer using the codes given below:

(a) 1 and 2 only

(b) 3 and 4 only

(c) 1, 2 and 4 only

(d) 1, 2, 3 and 4

(Sources: The weed threat to mustard, and the need to counter it with innovative solutions, How GM mustard was developed, why the question of its approval has now reached Supreme Court)

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