关键词: 马铃薯, 南方根结线虫, 抗性评价, 抗性基因, 抗性育种

Abstract:

【Objective】The southern root-knot nematode (Meloidogyne incognita) affects potato yield and quality. Screening for resistance to this nematode can provide a foundation for discovering new resistance genes and breeding resistant potato varieties. 【Method】The root-knot nematode was identified using PCR and propagated using water spinach. Southern root-knot nematodes were inoculated into 103 wild potato introgression lines at the seedling stage. After 35 days, root fresh weight was measured, and the number of root knots and egg masses were counted. Root knot index, egg index, and reproduction factor were calculated. Using statistical data, the membership function value was computed, and resistant materials were screened based on the membership function value and reproduction factor. The expression levels of 10 candidate resistance genes in potatoes at different stages were detected. The resistance evaluation results and the expression levels of candidate resistance genes were comprehensively analyzed to screen for wild potato introgression lines resistant to southern root-knot nematode. 【Result】The tested nematode as southern root-knot nematode. Among the 103 introgression lines, the number of root knots ranged from (8.00±3.61) to (359.00±242.00); the number of egg masses ranged from (1.00±0.00) to (483.67±5.69); the root knot index ranged from (0.62±0.28) to (36.59±2.21); the egg index ranged from (0.09±0.01) to (10 610±503.61); the reproduction factor ranged from (0.06±0.00) to (29.58±1.94); and the membership function value ranged from 1.96 to 4.98. Among these, lines 232-14 and 390-19 had the lowest root knot index, number of egg masses, root knot index, egg index, and reproduction factor, with values of (8.00±3.61) and (9.00±2.65), (1.00±0.00) and (1.33±0.58), (0.67±0.27) and (0.62±0.28), (0.09±0.01) and (0.09±0.05), and (0.06±0.00) and (0.08±0.03), respectively. Their membership function values were the highest, at 4.98 and 4.77, respectively. Lines 232-14, 390-19, 271-5, and 374-7 all had fewer than 100 egg masses and root knots. Line 271-5 exhibited lower root fresh weight and hypersensitive necrosis symptoms., with a higher egg index and reproduction factor. Expression profiling of candidate resistance genes revealed distinct temporal patterns: In line 390-19, overall gene expression exhibited a biphasic response to M. incognita infection, characterized by an initial upregulation followed by gradual decline, with Invertase inhibitor showing peak expression on the 1st day post-inoculation. Line 232-14 demonstrated significant upregulation of resistance genes specifically on the 3rd and 7th days after infection. Similarly, line 374-7 displayed a comparable biphasic expression pattern, where both PIN2 and Replication factor A reached their maximum expression levels on the 7th day post-infection. Resistance gene expression levels in line 374-7 were significantly lower overall than in line 390-19 and line 232-14. The highly suscep-tible control Burbank showed the lowest expression of resistance genes. 【Conclusion】This study identified introgression lines 232-14 and 390-19, with S.blb+R4 as the donor parent, as resistant wild potato introgression lines to southern root-knot nematode. The wild species S.blb can provide gene resources for resistance to southern root-knot nematode.

Key words: potato, southern root-knot nematode, resistance evaluation, resistance gene, resistance breeding