Short answers, pulled from the story.
The Vavilov center refers to specific geographic areas where cultivated plants were first domesticated with high genetic diversity. Nikolai Vavilov initially identified seven distinct regions as these birthplaces of essential crops in his 1924 scheme.
Nikolai Vavilov started with three centers in 1924 and expanded the list to five by 1926 before reaching seven in 1931. He finalized eight primary centers in 1935 but reduced the total back to seven in 1940 based on new data.
China stands alone as the largest independent center with one hundred thirty-six endemic plants including rice, soybeans, buckwheat, and peaches. The Indian Center follows closely with one hundred seventeen plants such as rice bean, eggplant, mango, and sugar cane.
The Fertile Crescent saw agriculture develop eleven thousand years before present during the Neolithic Revolution. This timeline predates the Yangtze and Yellow River basins which began cultivating crops nine thousand years ago and New Guinea Highlands which started between 9,000 and 6,000 BP.
Preventing genetic erosion requires active gene banks and habitat conservation efforts within identified centers of diversity to preserve wild relatives. Loss of germplasm due to disappearing ecotypes threatens humanity's ability to find disease-resistant genes needed for food security.