Institute for Sustainable Plant Protection of The National Research Council (IPSP-CNR), Portici, Italy.
INRAE, Pathologie Végétale, Montfavet, France.
PLoS One. 2024 May 9;19(5):e0302692. doi: 10.1371/journal.pone.0302692. eCollection 2024.
Tobacco vein necrosis (TVN) is a complex phenomenon regulated by different genetic determinants mapped in the HC-Pro protein (amino acids N330, K391 and E410) and in two regions of potato virus Y (PVY) genome, corresponding to the cytoplasmic inclusion (CI) protein and the nuclear inclusion protein a-protease (NIa-Pro), respectively. A new determinant of TVN was discovered in the MK isolate of PVY which, although carried the HC-Pro determinants associated to TVN, did not induce TVN. The HC-Pro open reading frame (ORF) of the necrotic infectious clone PVY N605 was replaced with that of the non-necrotic MK isolate, which differed only by one amino acid at position 392 (T392 instead of I392). The cDNA clone N605_MKHCPro inoculated in tobacco induced only weak mosaics at the systemic level, demostrating that the amino acid at position 392 is a new determinant for TVN. No significant difference in accumulation in tobacco was observed between N605 and N605_MKHCPro. Since phylogenetic analyses showed that the loss of necrosis in tobacco has occurred several times independently during PVY evolution, these repeated evolutions strongly suggest that tobacco necrosis is a costly trait in PVY.
烟草叶脉坏死（TVN）是一种由不同遗传决定因素调控的复杂现象，这些决定因素映射在 HC-Pro 蛋白（氨基酸 N330、K391 和 E410）和马铃薯 Y 病毒（PVY）基因组的两个区域中，分别对应细胞质内含体（CI）蛋白和核内含体蛋白酶 a-蛋白酶（NIa-Pro）。在 PVY 的 MK 分离株中发现了 TVN 的一个新决定因素，尽管它携带与 TVN 相关的 HC-Pro 决定因素，但不会诱导 TVN。坏死传染性克隆 PVY N605 的 HC-Pro 开放阅读框（ORF）被非坏死 MK 分离株的 ORF 取代，仅在第 392 位氨基酸（T392 而不是 I392）处存在差异。在烟草中接种 cDNA 克隆 N605_MKHCPro 仅在系统水平上引起弱嵌合体，证明第 392 位氨基酸是 TVN 的一个新决定因素。在烟草中，N605 和 N605_MKHCPro 的积累没有明显差异。由于系统发育分析表明，在 PVY 进化过程中，烟草坏死的丧失已经独立发生了多次，这些反复的进化强烈表明烟草坏死是 PVY 的一个代价高昂的特征。
