Question

Match List-I with List-II:
\includegraphics[width=0.6\linewidth]{94.png Choose the correct answer from the options given below:

• (A) - (II), (B) - (IV), (C) - (I), (D) - (III)
• (A) - (II), (B) - (IV), (C) - (I), (D) - (III) [Duplicate option in exam]
• (A) - (IV), (B) - (II), (C) - (I), (D) - (III)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

To remember major CMS sources:
Rice = Wild Abortive (WA, derived from wild rice).
Maize = Texas cytoplasm (T-cytoplasm, linked to leaf blight).
Sorghum = Combined Kafir (Milo cytoplasm).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Cytoplasmic Male Sterility (CMS) is a maternally inherited trait that prevents the production of functional pollen in plants.
CMS systems are widely used in hybrid breeding programs to eliminate the need for manual detasseling or emasculation, making commercial hybrid seed production economically viable.

Step 2: Detailed Explanation:
Let us correlate each crop with the specific source of cytoplasm used to induce male sterility:
1. Maize (A):
The most famous CMS source in maize is the Texas cytoplasm (T-cytoplasm), discovered in the late 1940s.
It was widely used until the early 1970s, when crops carrying T-cytoplasm were found to be highly susceptible to Southern Corn Leaf Blight caused by Bipolaris maydis race T.
Thus, (A) matches with (II).
2. Sorghum (B):
In grain sorghum, commercial hybrid production relies on the Milof-Kafir system.
The male-sterile lines are developed by introgressing the nuclear genome of Kafir cultivars into the cytoplasm of Milo cultivars, which is referred to as "Combined kafir" cytoplasm.
Thus, (B) matches with (IV).
3. Rice (C):
The development of hybrid rice in China was made possible by the discovery of a male-sterile wild rice plant (Oryza rufipogon) on Hainan Island.
The cytoplasm extracted from this plant is known as the "Wild abortive" (WA) cytoplasm, which is the most widely used CMS source in hybrid rice breeding globally.
Thus, (C) matches with (I).
4. Tobacco (D):
CMS in tobacco (Nicotiana tabacum) is often induced through interspecific crosses.
Placing the tobacco nuclear genome into the cytoplasm of wild relative species, such as Nicotiana microcephala (microcephalan), results in cytoplasmic male sterility.
Thus, (D) matches with (III).

Step 3: Final Answer:
The correct matching sequence is (A)-(II), (B)-(IV), (C)-(I), and (D)-(III). This corresponds to option (A).