RELATIONSHIP BETWEEN BIOCHEMICAL AND AGRONOMICAL CHARACTERISTICS AND THE CORN STUNT IN MAIZE

Abstract

Biochemical characteristics were evaluated in maize seedlings, as possible markers for selection of resistant genotypes to the corn stunt disease caused by Spiroplasma kunkelii, as well as the effect of this disease over the growth and grain production of maize genotypes. Spiroplasma was inoculated in the seedlings of the parental inbred lines P1, susceptible, and P2, resistant, and of the generations F1, F2 and F3. These inbred lines, also used in the intercrosses to obtain the other generations, were from the breeding program of the Brazilian Maize and Sorghum Corporation. The Plant Height (AP), ear height (AE) and grain production (PG) were affected by the spiroplasma with mean reductions of, respectively, 9.60%, 12.83% and 42.00% in these parameters. High values, above 0,80 were obtained in phenotypic and genotypic correlation between ear grade (NE) x corn stunt disease severity (SEV), between SEV x PG and between NE x PG, showing that these characteristics can be used as criteria for the selection of resistant genotypes to corn stunt. Among the biochemical characteristics evaluated, a tendency of the resistant plants to show higher values for soluble protein content and lower values for peroxidase specific activity (PODesp) was observed. The phenotypic correlation among the ferulic (FA) and 5,5’-di-ferulic (DFA) acids and SEV was not significant and the peroxidase zimograms did not present any isoforms that were associated specifically with resistance or susceptibility to corn stunt.

Keywords

• Zea mays
• peroxidase
• ferulic and 5
• 5’-di-ferulic acids
• spiroplasma
• Spiroplasma kunkelii