Q.58 Parthenocarpy which arises due to mutations or hybridization is known as
(1)Environmental Parthenocarpy
(2)Genetic Parthenocarpy
(3)Genetically Engineered Parthenocarpy
(4)Chemically Induced Parthenocarpy
Option (2) Genetic Parthenocarpy is correct.
Parthenocarpy due to mutations or hybridization qualifies as genetic parthenocarpy, as these are heritable genetic changes (e.g., hormone signaling mutants or polyploid hybrids) that trigger fruit development without fertilization, unlike environmentally or chemically induced forms.
Option Explanations
Parthenocarpy types distinguish inherent genetic triggers from external stimuli, relevant for seedless fruit breeding in crops like tomato, grape, and banana.
-
(1) Environmental Parthenocarpy: Incorrect. Caused by abiotic stress (low temperature, water deficit) mimicking pollination signals temporarily; not heritable or mutation/hybrid-based (e.g., cucumber under cold).
-
(2) Genetic Parthenocarpy: Correct. Arises from mutations (e.g., pat-2 tomato auxin mutants, SlAGL6 CRISPR knockouts) or hybridization (e.g., triploid bananas); seeds remain inviable, fruits develop autonomously via constitutive hormone pathways.
-
(3) Genetically Engineered Parthenocarpy: Incorrect. Specific to transgenic methods (e.g., DEFH68/DEFH9 overexpression in tomato); excludes natural mutations/hybrids.
-
(4) Chemically Induced Parthenocarpy: Incorrect. Uses exogenous auxins/gibberellins (e.g., GA3 sprays on pear); reversible, non-heritable.
Parthenocarpy mutations hybridization genetic questions test fruit development types in NEET/GATE Life Sciences, emphasizing heritable vs. induced seedless fruits.
Parthenocarpy Classification
-
Vegetative (Genetic): Spontaneous mutations/hybrids activate fruit-set genes (e.g., IAA, GA biosynthesis); stable, pollinator-independent.
-
Stimulative: External—environmental (stress), chemical (hormones), engineered (transgenes).
Genetic Examples
-
Mutations: Arabidopsis fie-1 (PRC2 defect), tomato pat mutants.
-
Hybrids: Seedless watermelon (2n×4n), grape cultivars. Fruits lack viable seeds but ripen normally.
Exam Tip
Key: “mutations or hybridization” = genetic (heritable DNA change). Exclude if “sprays” (chemical) or “temperature” (environmental).
