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Plant Breeding Approaches in Developing Stress Tolerance

6.5.3.1.1 Transgenic Approaches for Insect Pest Resistance

The insects and pests are the most diverse form of biotic stress in yield

destruction and increment in their number throughout their life cycle.

They are the major factor of the yield reduction of the food crops and are

leading to cause severe issues in the provision of food to the increasing

world population day by day (Douglas, 2018). The major two groups of

the damages in crops of insect pests are direct and indirect damages. Direct

damages caused by insect pests are plant cell and tissues death owing to

disgustingly dirty filled, accidental death of floral tissues and organ and the

whole process lead to the flourishment of the plant pathogen reproduction

as well as distribution. But the indirect damages are the fruits’ bruising

which causes an increase in expenses of management and reduction in

yield (Pappas et al., 2017). Recently reported that the yield loss of about

20% of horticultural crops globally. Research show that about 0.5% of

insect pest is responsible for major issue to human beings so that they

are called pest and belong to the Lepidoptera class (Zaidi et al., 2017).

Therefore, transgenic approaches are the best way to tackle the pest of

class Lepidoptera.

Transgenic approaches are the most appropriate and effective method to

tackle the insect pest with a high degree of success and in hand sum cost

(Majeed et al., 2018). In 1987 the 1^st transgenic insect-resistant tomato plant

was developed by utilizing the Cry gene from bacterium Bacillus thuringi­

ensis, which showed tolerance against Heliothis virescens and Spodoptera

litura. Mostly vegetables crops such as Bringle and chili are affected by

the class Lepidoptera (de Castro et al., 2017). Bt eggplant showing cry1Ab

and cry1Ac has produced and shows tolerance to the members of class

Lepidoptera (Biswas et al., 2018). Transgenic cabbage line DTC 507 trans­

formed having cry1Ab, and cry1B expressed tolerance to Plutella xylostella

(Parmar et al., 2017). The okra cry1Ac gene is introduced, showing toler­

ance against the Earias vittella (fruit borer) (Jan et al., 2015). Transgenic

strawberries show tolerance against vine weevil and aphids due to the

cowpea trypsin inhibitor (CpTi) gene (Singh et al., 2018). Transgenic crop

plants showing proteinase inhibitor genes are the most effective to tackle

root-knot nematode (Meloidogyne incognita) by checking their metabolism

(Zhang et al., 2015a, b, c). Effective resistance has been developed against

root-knot nematode in many crop plants like tomato, eggplant, and potato

(Seow-Neng et al., 2017).