02864naa a2200277 a 450000100080000000500110000800800410001910000230006024502260008326000090030930000090031852019350032765000120226265000220227465000130229665000220230965000250233165300210235665300380237770000190241570000230243470000180245770000250247570000160250077300700251621745722025-04-07       2025    bl uuuu     u00u1 u    #d1 aCARVALHO, I. C. B.  aResistance classification to bacterial blight (Xanthomonas phaseoli pv. manihotis) in Brazilian cassava (Manihot esculenta) cultivars, clones, and accessions using a novel qualitative ordinal scale.h[electronic resource]  c2025  a8 p.  aCassava (Manihot esculenta Crantz) is a staple food for over 800 million people worldwide. However, its production is severely impacted by diseases caused by viruses, fungi, and bacteria. Among these, cassava bacterial blight (CBB), caused by Xanthomonas phaseoli pv. manihotis (Xpm), is particularly damaging. This study aimed to classify the resistance of 11 cassava genotypes, including cultivars, clones, and accessions, using a novel ordinal qualitative scale. Isolate UnB 17 of Xpm, a highly virulent strain from Pará State, Brazil, was cultivated and inoculated into plants by spraying a bacterial suspension of 10⁸ CFU mL⁻1 . Inoculated and mock-inoculated plants were kept in a moist chamber for three days, then transferred to greenhouse conditions for the remainder of the experiment. Evaluations were conducted at 5-day intervals after inoculation. Visual symptomatology was pssessed based on a nine-point scale: 0 (no symptoms); 1 (water-soaked angular spots on ≤1/3 of the leaves); 2 (water-soaked angular spots on &gt1/3 of the leaves); 3 (necrotic spots/scorch symptoms on ≤1/3 of the leaves); 4 (necrotic spots/scorch symptoms on &gt1/3 of the leaves); 5 (necrotic lesions on the stem or petiole); 6 (necrotic lesions on the stem or petiole with exudation); 7 (wilting with exudation or death of ≤1/3 of the plant); and 8 (wilting with exudation or death of &gt1/3 of the plant). The data obtained from this rating scale were used to calculate the Area Under the Disease Progress Curve (AUDPC). Hierarchical clustering and the Elbow method identified three resistance groups: moderately resistant, moderately susceptible, and susceptible. No genotype exhibited complete resistance, as all showed typical symptoms of CBB. This study emphasizes the need for repeated trials across different periods and environmental conditions to better understand the resistance and susceptibility of cassava genotypes.  aCassava  aMancha Bacteriana  aMandioca  aManihot Esculenta  aVariedade Resistente  aBacterial blight  aXanthomonas phaseoli pv manihotis1 aLIMA, H. P. R.1 aCARVALHO, A. M. S.1 aVIEIRA, E. A.1 aLOURENÇO JUNIOR, V.1 aROSSATO, M.  tTropical Plant Pathologygv. 50, Feb. 2025. Número do artigo 27.