Seed treatments with the plant symbionts Trichoderma harzianum strain T22 results in root colonization and about a 5 bushel per acre yield increase over several hundred field trials. However, results have been quite variable, with yield changes ranging from about 50 bu/acre to actual yield decreases. We have demonstrated that the yield change is determined by unknown maize genetic factors. We expect (a) to identify inbred and hybrid lines that respond strongly positively to T22 and to recommend use of products based upon it only on these positive responding lines, (b) to identify rapid predictive tests for the response and model the relationship between field results and the rapid test, and (c) in related and Phase II R&D to identify the actual genetic factors that give rise to the response. T22 also increases plant resistance to disease and the inheritance; the prediction of results and the genetic nature of this response also will be determined. The purpose of this study is to determine the predictability of maize yields and enhanced diseases resistance in maize genotypes treated with T-22. OBJECTIVES: To determine that predictability and nature (straight line or other) of changes in maize growth at two weeks relative to yield of maize in field trials of 20 hybrids and the inbreds from whence they came; (2) to determine whether changes in the growth response is simply inherited, and, if so, whether the positive response is genetically dominant over neutral or negative responses, (3) to determine whether the increased growth response is genetically linked to the induced resistance response and (4) to determine the effects of induced systemic resistance in field grown maize and (5) to begin production of inbred recombinant lines of Mo17 x A661, two publicly available inbreds, for genetic analysis in phase II. APPROACH: Seed treatments with the plant symbionts Trichoderma harzianum strain T22 has been demonstrated to increase growth and yield of maize and to increase resistance to diseases. However, there are genetic differences in the response of maize lines to T22. It is the purpose of phase I of this proposal to compare a rapid two-week growth assay of different lines of maize and yield differences in the field. A comparison of these two data sets across the same lines will indicate the nature of the predictive test and to model its relationship to actual field results. By comparing both inbreds and hybrids in these tests we will discover the nature of the inheritance of the response. In ongoing and expected phase II research the actual genes and specific inheritance that condition the T22 are expected to be discovered
