Disease and Insect Resistance Genes in Premium Sterile Line Funong A

Objective Disease and insect resistance genes in Funong A, a three-line indica cytoplasmic male sterile line, were analyzed for breeding applications.

Method  Genomic DNA of Funong A, Fudao B, and Huahangsimiao rice germplasms was extracted by CTAB method followed by detection of blast resistance genes with molecular markers. Resistance genes related to bacterial blight, viral diseases, and brown planthopper infestation were analyzed by high density chip detection method. Blast resistance genes of the lines were obtained by PCR and sequenced for comparison. Specimens were collected at 0, 24, 48, 72, and 96 h after a blast fungus inoculation for extraction of total RNA using Trizol method. Gene expression was determined by SYBR Green I qRT-PCR.

Result Funong A, Fudao B, and Huahangsimiao were found to contain the blast resistance genes Pib, Pia, Pid3, Pid2, bacterial blight resistance gene Xa21, and yellow mottle virus resistance gene Rymv1. Furthermore, Funong A and Huahangsimiao had the blast resistance gene Pi5 and the stripe virus resistance gene STV11, while Fudao B consisted of the blast resistance genes Pita and Pi37. However, no brown planthopper resistance genes were detected in them. The fragments of Pi5, Pia, Pib, Pid3, and Pid2 were 5 672 bp, 2 597 bp, 5 532 bp, 2 865 bp, and 3 847 bp in length, respectively. The sequences of Pi5, Pid3, and Pid2 in Funong A were similar to those in Huahangsimiao, but 2 bases differed from Pid3 and 5 from Pid2 of Fudao B. In Funong A, the expressions of rice blast resistance genes Pi5 and Pib were significantly induced by the blast fungus with a peak occurred 72 h after inoculation. The expressions of Pia and Pid3 increased gradually with time after inoculation to peak in 96 h. The expression of Pid2 rose initially to a maximum in 24 h and then declined.

Conclusion The three-line indica cytoplasmic male sterile line Funong A carried the blast resistance genes Pi5, Pib, Pia, Pid3, and Pid2, which were significantly induced by the blast fungus. The line also contained the bacterial blight resistance gene Xa21, yellow mottle virus resistance gene Rymv1, and stripe virus resistance gene STV11 but none of the insect resistance genes.