Besides resistance to pests, what are the other prospects for which plants have been genetically engineered ? 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 :

Correct — C, (c) 1, 2 and 4 only.

The stem sets aside pest resistance, which is the best-known application, and asks which of the four remaining purposes are genuine PROSPECTS for genetic engineering in plants. Three of the four are established lines of work with named products; the fourth is not.

STATEMENT 1 — 'To enable them to withstand drought.' A GENUINE PROSPECT. Abiotic stress tolerance — drought, salinity, heat, cold — is one of the largest targets in plant biotechnology, because it addresses the yield losses that no amount of pest control can prevent. Drought-tolerant transgenic maize has been commercialised, and drought tolerance is a stated objective of transgenic and gene-edited programmes in cereals worldwide. It is a harder trait than pest resistance because it is controlled by many genes rather than by one, which is why progress has been slower than in insect resistance.

STATEMENT 2 — 'To increase the nutritive value of the produce.' A GENUINE PROSPECT, and the best-known example in the whole field. Golden Rice was engineered to accumulate beta-carotene, a precursor of vitamin A, in the endosperm — the part of the grain that is eaten — in order to address vitamin A deficiency in populations whose staple is polished rice. Work of the same kind targets iron and zinc content, protein quality and the fatty-acid composition of oilseeds. This general objective is called biofortification.

STATEMENT 3 — 'To enable them to grow and do photosynthesis in spaceships and space stations.' NOT a prospect for which plants have been genetically engineered. Plants have certainly been GROWN in space — plant growth chambers have been flown for decades — but that is a matter of engineering the ENVIRONMENT, not the plant. Photosynthesis requires light, carbon dioxide and water, all of which a spacecraft supplies; nothing about photosynthesis itself has to be redesigned for the plant to work in orbit. The real difficulties of growing plants in space are microgravity, radiation, water delivery without convection and constrained volume, and they are addressed by the design of the growth chamber. This statement is the fabricated one in the set, and it is fabricated in a way that sounds like frontier science.

STATEMENT 4 — 'To increase their shelf life.' A GENUINE PROSPECT, and historically the first. The Flavr Savr tomato, cleared for sale in the United States in 1994, was the first genetically engineered whole food brought to market, and its modification did exactly this: it suppressed the enzyme responsible for softening so that the fruit could ripen on the plant and still survive transport. Delayed ripening and reduced browning remain active objectives, since post-harvest loss is one of the largest sources of waste in food systems.

Statements 1, 2 and 4 stand and statement 3 does not, so the answer is option (c). None of the four numbered statements ends in a full stop in the booklet, unlike those of the preceding question.

Why the others are wrong

• (a)1, 2 and 3 only — This admits the space-photosynthesis statement and drops shelf life — which is the reverse of the truth in both places. Extended shelf life is not merely a prospect but the objective of the first genetically engineered whole food ever sold, the Flavr Savr tomato of 1994. Statement 3, by contrast, confuses growing plants in a spacecraft with engineering plants for a spacecraft; the first has been done for decades using ordinary plants in purpose-built growth chambers, and the second is not a research objective because photosynthesis does not need to be redesigned for orbit.
• (b)3 and 4 only — This keeps the one false statement and one true one, while discarding the two most substantial applications in the field. Drought tolerance is among the largest objectives in agricultural biotechnology, because abiotic stress causes yield losses that pest control cannot touch; and nutritional enhancement gave the field its most famous single product in Golden Rice. An option that excludes both of those while retaining a spaceflight application has the subject almost exactly upside down.
• (d)1, 2, 3 and 4 — The all-inclusive option, and the one a candidate reaches for when every statement sounds futuristic and therefore plausible. Three of the four are correct, which is exactly why this option is tempting: the item turns on identifying the single statement that does not belong. The discipline is to ask of each statement not 'could this be done ?' but 'is this something plants are actually engineered FOR ?' Growing plants in space is a genuine activity; genetically engineering them so that they can photosynthesise there is not the way that activity is pursued, because the constraints of spaceflight are physical rather than biochemical.

Genetic engineering in plants means introducing, removing or altering specific genes to give the plant a trait it did not have. The objectives fall into a small number of families, and knowing the families with one named example each answers most questions in this area.

BIOTIC STRESS RESISTANCE — resistance to insects, viruses and fungi. The Bt crops, which carry a gene from the soil bacterium Bacillus thuringiensis coding for a protein toxic to specific insect larvae, are the largest group. This is what the stem sets aside. HERBICIDE TOLERANCE — allowing a broad-spectrum herbicide to be applied over the crop. Commercially the largest single trait by area planted. ABIOTIC STRESS TOLERANCE — drought, salinity, heat, cold, flooding. Harder, because these traits are polygenic. QUALITY AND NUTRITION — biofortification. Golden Rice for provitamin A is the standard example; iron and zinc enhancement and altered oil composition are others. POST-HARVEST TRAITS — delayed ripening, reduced browning, longer shelf life. The Flavr Savr tomato of 1994 was the first such product to market. MOLECULAR FARMING — using plants as production systems for pharmaceuticals, vaccines and industrial materials.

INDIA'S POSITION is worth carrying alongside. Bt cotton is the only genetically modified crop approved for commercial cultivation in India. Bt brinjal received a regulatory recommendation but was placed under a moratorium in 2010 and has not been released. The regulator is the Genetic Engineering Appraisal Committee, which functions under the Ministry of Environment, Forest and Climate Change under rules made in 1989 under the Environment (Protection) Act, 1986.

The technique to carry away from this item is how a false statement is built in this subject. It is not built by stating something impossible; it is built by taking a real activity — growing plants in space — and attributing it to the wrong mechanism. The test is always whether the STATED PURPOSE matches what genetic engineering is actually used for, not whether the sentence describes something that happens.

Key facts

• Drought and other abiotic stress tolerance is a major objective of plant genetic engineering, and harder than pest resistance because such traits are controlled by many genes.
• Golden Rice was engineered to accumulate beta-carotene, a precursor of vitamin A, in the rice endosperm, to address vitamin A deficiency — the standard example of biofortification.
• The Flavr Savr tomato, cleared for sale in the United States in 1994, was the first genetically engineered whole food brought to market, and its modification delayed softening to extend shelf life.
• Plants have been grown in space for decades in purpose-built growth chambers; the difficulties are microgravity, radiation, water delivery and volume, and they are solved by engineering the environment rather than the plant.
• Photosynthesis requires light, carbon dioxide and water, all of which a spacecraft supplies, so it does not need to be redesigned for orbit.
• Bt crops carry a gene from Bacillus thuringiensis coding for a protein toxic to specific insect larvae; herbicide tolerance is the largest single engineered trait by area planted.
• Bt cotton is the only genetically modified crop approved for commercial cultivation in India; the regulator is the Genetic Engineering Appraisal Committee under the Ministry of Environment, Forest and Climate Change.

Common traps

• Accepting a statement because it sounds like advanced research. In a science list the most spectacular statement is more often the planted error than the reward.
• Confusing growing plants in space with engineering plants for space. The first is routine; the second is not how the problem is approached.
• Overlooking shelf life as an application. It produced the first genetically engineered whole food ever sold.
• Missing the stem's exclusion of pest resistance, which is the one application most candidates can name and the one the question deliberately removes.

• practice — not a real PYQ

  Golden Rice was genetically engineered principally to

  • (a)resist attack by the rice stem borer
  • (b)tolerate submergence during floods
  • (c)accumulate a precursor of vitamin A in the grain
  • (d)tolerate application of a broad-spectrum herbicide

  Answer(c) accumulate a precursor of vitamin A in the grain — beta-carotene was engineered into the endosperm, the part of the grain that remains after polishing, to address vitamin A deficiency in populations dependent on rice. It is the standard example of biofortification through genetic engineering.

• practice — not a real PYQ

  The gene used in Bt crops to confer insect resistance is derived from

  • (a)a soil bacterium
  • (b)a virus infecting the crop
  • (c)a wild relative of the crop plant
  • (d)a marine alga

  Answer(a) a soil bacterium — Bacillus thuringiensis, which produces crystal proteins toxic to the larvae of particular insect groups. Transferring the gene for such a protein into the crop makes the plant itself express the toxin. Bt cotton is the only genetically modified crop approved for commercial cultivation in India.