1a.Objectives (from AD-416)
The primary objective of this work is to develop techniques and methods that will lead to sterile or highly infertile cultivars of invasive or potentially invasive nursery crops.
1b.Approach (from AD-416)
The general approach is to use use biotechnology or genetic engineering to create seedless plants or to develop methods that will lead to the creation of seedless plants. One area of study will be to test gene suppression using the AGAMOUS gene and dsRNA-RNAi. The AGAMOUS gene is a floral homeotic gene that, when suppressed or mutated, can result in flowers that have petals in place of pistils and stamens, and are therefore sterile. The second area of study will be to create transgenic plants using several different gene constructs that may induce male and/or female sterility.
The primary objective of this work is to develop techniques and methods that will lead to sterile or highly infertile cultivars of invasive or potentially invasive nursery crops. Transgenic sweetgum trees planted in the field three years ago continue to grow well, showing similar or greater growth than the wild-type controls that were also propagated in vitro and transplanted at the same time. Growth ranking has been highly stable from year to year. Tissue samples were collected from all transgenic plants in July 2010, and optimization of RNA extraction from the leaf tissue is underway. PCR primers for qPCR will be designed for the 26S and 18S ribosomal RNA and other genes from sweetgum. In our efforts to develop sterility genes, we constructed two gene constructs based on the poplar LEAFY gene but controlled by the native poplar promoter and the 35S constitutive promoter. Two poplar genotypes were co-transformed with two different constructs using the FT gene to speed flowering, and one of the two EAR motif genes. One construct had a kanamycin selectable marker, and the others had a basta selectable marker, and both types of antibiotic were used in the selection medium. Unfortunately, the rates of transformation were unusually low in this experiment, possibly due to the physiological stress from dual antibiotic selection. In addition, they were substantially lower for the EAR motif constructs than for the FT construct, indicating that the EAR motif genes may have lethal effects at early stages of cellular differentiation. We will be producing new transformants with these constructs during the upcoming year. We are also working on a problem analysis of approaches to reducing invasiveness by studying the state of in vitro culture, transformation and genomics of invasive and potentially invasive landscape plants.
Research activities conducted under this agreement were monitored by regular email communication, submission of reports by the cooperator, and by in-person communication at scientific and stakeholder meetings.