Genetically Modified mustard (GM mustard)

RELEVANCE – UPSC GS PRELIMS & GS MAINS – III

First go through the text (given after the questions) and then attempt the questions.

UPSC QUESTIONS

UPSC 2018

QUES . With reference to the Genetically Modified mustard (GM mustard) developed in India, consider the following statements :

1. GM mustard has the genes of a soil bacterium that give the plant the property of pest-resistance to a wide variety of pests.
2. GM mustard has the genes that allow the plant cross-pollination and hybridization.
3. GM mustard has been developed jointly by the IARI and Punjab Agricultural University.

Which of the statements given above is/are correct ?

(a)1 and 3 only
(b)2 only
(c)2 and 3 only
(d)1, 2 and 3

Answer. b

PRACTICE QUESTIONS

QUES 1 . Consider the following statements :

1 . Mustard flower is pre-dominantly a cross pollinated crop.

2 . Male sterile lines can be developed in mustard  through  genetic engineering using transgenes.

Which among the above statements is/are correct?

a . 1 only

b . 2 only

c . Both 1 and 2

d . Neither 1 nor 2

Answer –b

QUES 2 . Genes – barnase and barstar used for producing GM mustard can be obtained from  bacterium –

a . Bacillus thuringiensis

b . Bacillus subtilis

c . Bacillus alcalophilus

d . Bacillus amyloliquefaciens

Answer -d

ABOUT GM MUSTARD

Developer of this new technology 

Centre for Genetic Manipulation of Crop Plants (CGMCP), University of Delhi, South Campus, New
Delhi has developed this Barnase-Barstar technology

About the technology 

Mustard flowers contain both male and female organs and the crop is pre-dominantly self-pollinating. Therefore, a pollination control mechanism is required to disallow self-pollination and encourage cross-pollination for hybrid seed production.

For this, one of the two parental lines of a hybrid has to be made male sterile so that it receives pollen from the other parent to set seed. Seeds harvested from the male sterile line are hybrid seeds which can be provided to the farmers, who can reap the benefit of higher productivity of the hybrids.

Male sterile lines can be developed by using cytoplasmic male sterility (CMS) through conventional breeding or by genetic engineering using transgenes.

Cytoplasmic male sterility (CMS)

A number of CMS systems have been tested in mustard. However, CMS/ restorer systems have been found to be inadequate for large scale hybrid seed production with high purity. CMS systems are either unstable or their restoration to fertility is inadequate.

A more versatile hybrid seed production system is based on the use of transgenes – barnase and barstar as explained below.

Barnase-barstar system

A novel way to developing male sterile (MS) lines through genetic engineering was developed by
scientists in Belgium in early 1990s through the use of two genes – barnase and barstar from soil
bacterium Bacillus amyloliquefaciens. In nature, bacterium excretes a defense protein called Barnase
(a type of ribonuclease) which degrades the RNA of competing bacteria in an ecological niche. To
protect itself from Barnase, the bacterium produces another protein called Barstar which tightly binds
with Barnase and renders it ineffective.

Bacterial genes can only express in plants if these are expressed under plant promoters. Both Barnase and Barstar encoding genes were expressed under a
tapetum specific promoter. Tapetum is a layer of cells in the male organs called anthers present in the flower. Tapetum produces metabolites which are essential for the development of mature pollen.

In the barnase gene containing lines, the tapetum tissue ablates (dies),as a consequence developing pollen degenerate, providing MS lines. The other parental line, called restorer of fertility (RF) line, contains barstar gene that also expresses in the tapetum cells.

The MS line receives pollen from the RF line through wind pollination or bee pollination, resulting in the production of hybrid seed that has both the barnase and the barstar genes. When hybrids are grown by the farmer these are fully fertile.

Thus the MS/ RF system ensures that the MS line will only produce hybrid seeds by outcrossing with RF lines thereby providing an efficient system of pollination control for production of hybrid seed. The system hereafter is referred to as barnase-barstar system.

Issues of concern for the environment

Issues of concern include –

1 . Capability of the GE Plant to escape and potentially introduce the engineered genes into wild populations

2 . Persistence of the gene after the GE Plant has been harvested

3 . Susceptibility of non-target organisms (e.g. insects which are not pests) to the gene
product

4 . Stability of the gene

5 . Reduction in the spectrum of other plants including loss of biodiversity

6 . Increased use of chemicals in agriculture.

Are GM foods safe?

Different GM organisms include different genes inserted in different ways. This means that individual GM foods and their safety should be assessed on a case-by-case basis and that it is not possible to make general statements on the safety of all GM foods. GM foods currently available on the
international market have passed safety assessments and are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved.

Current status about introduction of GM mustard

The Genetic Engineering Appraisal Committee (GEAC), India’s regulator for genetically modified seeds, had on May 12,2017 cleared GM mustard for environmental release and use in fields. Though it was cleared by scientists, the Environment Ministry’s approval is still awaited. Dhara Mustard Hybrid (DMH -11) is the transgenic mustard in question.