Plant Growth Regulators Produced by Microorganisms

Several plant growth regulators were isolated from the culture broths of microorganisms, mainly phytopathogenic fungi, and their structures were determined. Helminthosporol ( 1 ) isolated from Helminthosporium sativum markedly promoted stem elongation of rice seedlings. From Exobasidium symplocijaponica was obtained L-s-phenyllactic acid ( 7 ) as a root growth promoter. Pestalotin ( 8 ) was isolated from Pestalotia cryptomeriaecola . The compound 8 enhanced the growth-stimulative effect of GA when applied in combination with the hormone. 2-Pyruvoylaminobenzamide ( 9 ) was isolated from Colletotrichum lagenarium as an antiauxin-like substance. From Cylindrocladium scoparium was obtained Cyl-2 as a growth inhibitor. Some Phytotoxins that cause disease in tobacco plants were isolated from Colletotrichum nicotianae : colletopyrone ( 11 ), colletotrichin ( 12 ). colletotrichin B ( l3 ) and colletotrichin C ( 14 ).