Tetraose steroidal glycoalkaloids from potato provide resistance against Alternaria solani and Colorado potato beetle oleh Pieter J Wolters, Doret Wouters, Yury M Tikunov, Shimlal Ayilalath, Linda P Kodde, Miriam F Strijker, Lotte Caarls, Richard GF Visser, Vivianne GAA Vleeshouwers