Yeh bacterium naturally sporulation ke dauran ek protein banata hai, jo crystals ki tarah store hota hai — isliye gene ka naam cry hai (crystal protein), aur toxin ko Cry protein (ek δ-endotoxin) kehte hain. Yeh bacterium ka chemical weapon hai soil mein compete karne wale insects ke against.
Toxin kaise active hota hai (mechanism, step by step):
Insect larva plant khaata hai → inactive protoxin crystals nigal leta hai.
Insect ka gut strongly alkaline hota hai (high pH). Alkaline pH crystal ko dissolve karta hai aur protoxin ko release karta hai.
Gut ki proteases protoxin ko cleave karke active toxin banati hain.
Active toxin specific receptors on the midgut epithelium se bind karta hai.
Yeh gut cell membranes mein pores banata hai → cells swell aur burst ho jaate hain (osmotic lysis) → gut lining collapse ho jaati hai → insect khaana band kar deta hai aur mar jaata hai.
Glyphosate plant enzyme EPSP synthase ko inhibit karta hai, jo shikimate pathway ka hissa hai jisme aromatic amino acids bante hain. Blocked pathway ⇒ plant starve hota hai ⇒ mar jaata hai.
Engineered crops mein enzyme ka ek glyphosate-insensitive version hota hai (aksar bacterium se liya cp4 EPSPS gene). Herbicide usse bind nahi kar sakta, isliye crop amino acids banata rehta hai aur zinda rehta hai.
Farmer ko kya faayda hota hai: ek spray weeds hata deta hai → kam manual weeding, kam soil disturbance (kam tillage) → lekin over-reliance aur resistant "superweeds" ka risk bhi note karo.
Toxin bacterium mein harmless kyun hota hai? → inactive crystal (protoxin) ki tarah stored hota hai
Insect gut mein toxin activate karne ke liye do conditions? → alkaline pH + specific midgut receptor
Cotton bollworm ko kaun sa gene protect karta hai? → cryIAc / cryIIAb
Glyphosate weeds ko kaise maarta hai? → EPSP synthase (shikimate pathway) ko inhibit karta hai
Crop ko glyphosate-tolerant kaise banate hain? → glyphosate-insensitive EPSPS gene insert karte hain
Recall Feynman: ek 12-saal ke bacche ko explain karo
Socho ek gobhi jisme ek chhoti si "bad-taste bomb" copy ki gayi hai ek soil germ se. Bomb ek locked box ke andar band hai aur kuch nahi karta — jab tak koi caterpillar patti nahi kaatta. Caterpillar ka pet saabun wale paani jaisa hota hai (alkaline); woh box dissolve kar deta hai, bomb khul jaata hai, aur caterpillar ke pet mein holes ho jaate hain, isliye woh khaana band kar deta hai aur mar jaata hai. Tumhara pet nimbu ke juice jaisa hota hai (acidic), isliye box kabhi khulta hi nahi — tum bilkul theek ho. Yahi ek Bt crop hai. Weeds ke liye, hum ulta trick karte hain: hum crop ko ek secret handshake sikhaate hain taaki weed-killer spray use pakad na sake. Field spray karo — weeds maarte hain, crop survive karta hai. Yahi herbicide resistance hai.
Tissue culture and totipotency — poore plants regenerate karna
Pest resistant plants (RNAi) — ek alternative anti-pest strategy
GEAC and biosafety — GM crops ki regulation
Bt crops mein "Bt" abbreviation ka matlab kya hai?
Bacillus thuringiensis, woh soil bacterium jo toxin gene deta hai.
Bt toxin code karne wali gene family ka naam kya hai, aur kyun?
cry genes — kyunki toxin crystal (Cry) protein ki tarah stored hota hai.
Bt toxin kis form mein produce hota hai, active ya inactive?
Inactive protoxin (crystalline), sirf insect gut mein activate hota hai.
Bt protoxin activate karne ke liye do conditions kaun si hain?
Alkaline gut pH (crystal dissolve karta hai) + ek specific midgut receptor (binding ke liye).
Active Bt toxin insect ko kaise maarta hai?
Midgut epithelial receptors se bind karta hai aur pores banata hai → cells swell aur lyse ho jaate hain → insect khaana band kar deta hai aur mar jaata hai.
Bt humans aur cattle ke liye safe kyun hai?
Acidic stomach crystal ko solubilise nahi kar sakta, aur hamare gut cells mein specific receptor nahi hota.
Cotton ko bollworm se kaun se cry genes protect karte hain?
cryIAc aur cryIIAb.
Corn ko corn borer se kaun sa cry gene protect karta hai?
cryIAb.
Herbicide-resistant crop define karo.
Ek aisa crop jo broad-spectrum herbicide spray survive karne ke liye engineer kiya gaya hai, jisse farmer weeds ko maare bina crop ko nuksaan pahunchaye.
