The first gene-sequenced crop is :

The correct option is Rice.

To understand why rice was the first crop to have its genome sequenced, let us break down the scientific reasoning and historical context:

1. Small Genome Size:
Among the major cultivated cereal crops, rice (Oryza sativa) has a relatively small and compact genome. Its genome consists of approximately 430 million base pairs (Mb) across 12 chromosomes. In comparison, other major crops have vastly larger and more complex genomes. For example, the genome of wheat is hexaploid and extremely large (roughly 17,000 Mb), which made it impossible to sequence using early sequencing technologies.

2. The Reference Model for Cereal Crops:
Because of its small genome size and its close evolutionary relationship to other key cereal crops (like corn, wheat, and barley), rice was selected as the ideal model organism for grass and crop genomics. Sequencing rice provided a foundational map to help understand the genetics of other, more complex crops.

3. Timeline of Sequencing:
The International Rice Genome Sequencing Project (IRGSP), a joint effort involving laboratories worldwide, began sequencing the rice genome in the late 1990s. Draft versions of the genome were published in 2002, and the high-quality, finished sequence was published in 2005. This established rice as the very first crop genome to be fully sequenced, predating the sequencing of wheat, tobacco, and cotton.