Prothction of disease-resistant plants by cell engineering using host-specific toxins of pathogens

已知某些真菌病原体产生宿主特异性毒素（HST），所述宿主特异性毒素决定它们的宿主范围并有助于它们的毒力或致病性。近年来，利用HST从感病植物中培育抗病基因型的技术相对流行。在许多植物中，通过培养组织或细胞的生长产生的体细胞突变释放新的抗病性状，HSTs被用于这些性状的离体选择，我们发现，芸苔链格孢、黄瓜病原型和番茄病原型的Corynespora coconicola和Stemphylococcus vesicarium产生新的HSTs，分别命名为AB-、CCC-、CCT-和SV-毒素。AB-毒素是一种蛋白质，分子量约为35 kDa，而CCT-毒素是一种分子量为2，780的环肽。黄瓜褐斑病菌番茄致病型的CCT-毒素用于生产抗病番茄。从番茄下胚轴诱导出具有高再生频率的绿色斑点的愈伤组织，并将其转移到含有CCT毒素的MS培养基上。虽然几乎所有的愈伤组织都变成褐色，但有些愈伤组织甚至在孵育3周后仍继续存活。但是，耐毒素的愈伤组织失去了再生能力。另一方面，互隔孢霉番茄致病型产生HST（AAL-毒素）。最近，从黑酵母Exophilia spinifera中克隆了代谢AAL毒素的ESP 1。因此，本研究试图通过对转ESP 1基因番茄中AAL毒素的脱毒来获得抗病番茄。利用农杆菌介导的ESP 1双元载体转化番茄。然而，尚未获得转化体。

Certain fungal pathogens are known to produce host-specific toxins (HSTs) that determine their host range and contribute to their virulence or pathogenicity. Recently, technology for breeding disease-resistant genotypes from susceptible plants by using HSTs is relatively prevalent. In many plants, somatic mutations generated through the growth of tissues or cells in culture release novel disease resistance characters, and HSTs are used to select in vitro for such characters.We found that Alternaria brassicicola, cucumber pathotype and tomato pathotype of Corynespora cassiicola, and Stemphylium vesicarium produce new HSTs named AB-, CCC-, CCT- and SV-toxins, respectively. AB-toxin was a protein and estimated to be 35 kDa, and CCT-toxin was a cyclic peptide with molecular weight of 2,780.CCT-toxin of C.cassiicola tomato pathotype was used for production of disease-resistant tomato. Tomato calli with green spots which have a high regeneration frequency were induced from hypocotyls and transferred to MS medium containing CCT-toxin. Although almost all calli became brown, some calli continued to survive even after incubation for 3 weeks. However, the toxin-tolerant calli lost ability to regenerate. On the other hand, A.alternata tomato pathotype produces a HST (AAL-toxin). Recently, the ESP1 which metabolizes AAL-toxin was cloned from black yeast Exophilia spinifera. Therefore, production of disease-resistant tomato by detoxification of AAL-toxin in ESP1-transgenic tomato was attempted. Transformation of ESP1 in tomato was performed by Agrobacterium tumefaciens containing binary vector with ESP1. However, transformants have not yet been obtained.