RESUMEN
In the North Eastern Himalayan region (NEHR) of India, maize is an important food crop. The local people cultivate the maize landraces and consume them as food. However, these landraces are deficient in ß-carotene content. Thus, we aimed to incorporate the crtRB1 gene from UMI285ß+ into the genetic background of the NEHR maize landrace, Yairipok Chujak (CAUM66), and thereby enhance the ß-carotene content through marker-assisted backcrossing (MABC). In this regard, we backcrossed and screened BC1F1 and BC2F1 plants possessing the heterozygous allele for crtRB1 and then screened with 106 polymorphic simple sequence repeat (SSR) markers. The plants having maximum recurrent parent genome recovery (RPGR) were selected in each generation and selfed to produce BC2F2 seeds. In the BC2F2 generation, four plants (CAUM66-54-9-12-2, CAUM66-54-9-12-11, CAUM66-54-9-12-13, and CAUM66-54-9-12-24) having homozygous crtRB1-favorable allele with maximum RPGR (86.74-90.16%) were selected and advanced to BC2F3. The four selected plants were selfed to produce BC2F3 and then evaluated for agronomic traits and ß-carotene content. The agronomic performance of the four lines was similar (78.83-99.44%) to that of the recurrent parent, and ß-carotene content (7.541-8.711 µg/g) was on par with the donor parent. Our study is the first to improve the ß-carotene content in NEHR maize landrace through MABC. The newly developed lines could serve as potential resources to further develop nutrition-rich maize lines and could provide genetic stock for use in breeding programs.
