番茄雄性株类病毒对‘TOMR0902’番茄的生物学影响研究

Study on the biological effects of tomato planta macho viroid on‘TOMR0902’tomato

0引言番茄雄性株类病毒(tomato planta macho viroid,TPMVd)属于马铃薯纺锤块茎类病毒科(Pospiviroidae)马铃薯块茎类病毒(Pospiviroid),大小约为360 nt[1-2]。最初,有研究者在结实率严重下降的番茄(Solanum lycopersicum L.)[3-4]植株中分离获得了一种具有侵染性的环状核苷酸,摩擦接种健康番茄可引起接种植株的结实率严重降低,经序列测定后命名为TPMVd。后来,有研究者也在野生马铃薯(Solanum cardiophyllum L.)中发现一种类似核酸分子,其核苷酸序列与TPMVd相似,命名为墨西哥薯类病毒(Mexican papita viroid,MPVd)[5]。

Tomato planta macho viroid(TPMVd),previously designated as Mexican papita viroid,can infect tomato(Solanum lycopersicum)and other solanaceae plants,resulting in severe losses of the infected plants.With the increase of worldwide germplasm resources exchanges,TPMVd has become a big threat to the solanaceae crops,and it should be quarantined and inspected timely.However,the biological characteristics of TPMVd remain limited since it has not been assessed on commercial tomato varieties in China,even though there has been pathogenic test on the indicator‘Rutgers'tomato.Here,TPMVd plasmids were transcribed to infectious RNAs and mechanically ground onto‘TOMR0902'tomato seedlings that are widely cultured in China,and kept in green house for 60 days.The inoculated seedlings together with the controls were subjected to detection of TPMVd by RT-PCR at 60 days post inoculation(dpi),and the resulting products with a size of 360 bp were cloned and sequenced.The results confirmed that the symptomatic seedlings were infected with TPMVd.Moreover,a digoxin-labeled RNA riboprobe of TPMVd with a detectable titer of 10^(-6)was also synthesized,and it can detect TPMVd with a titer as low as 3 ng·μL^(-1)based on sensitivity assessment using transcribed RNAs,but failed to detect TPMVd in the inoculated tomato seedlings,suggesting that the viroid remains under a detection limit in the inoculated seedlings.The symptoms were developed on the seedlings infected by TPMVd,including severe dwarf,epinasty leaves and curly shoots,which are similar to the previously described symptoms on‘Rutgers'seedlings but with some divergence.This study confirms that TPMVd possesses a severe threat to a commercial tomato variety,and develops molecular and biological detection techniques used for controlling its spread.