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Title: FLORAL BUD AND MEAN PETAL LENGTH AS MORPHOLOGICAL PREDICTORS OF MICROSPORE CYTOLOGICAL STAGE IN LESQUERELLA.

Author
item TOMASI, P - UNIV OF AZ, TUCSON, AZ
item BACKHAUS, R - ASU, PHOENIX, ARIZONA
item Dierig, David
item PIGG, K - ASU, PHOENIX, ARIZONA

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Traditional means of improving beneficial crop traits are a time-consuming process. The use of pollen culture, which is the growth of plants from pollen grains, could possibly alleviate some of the labor-intensive problems associated with traditional breeding techniques. A developed pollen culture process could lead to beneficial traits appearing in a farmer's crop earlier than would be possible by traditional methods. The alternative procedure of pollen culture has not been established for the promising new oilseed crop, Lesquerella fendleri. Lesquerella produces a distinct seed oil with elevated levels of an unsaturated hydroxy fatty acid similar to castor oil. Such oils are currently being imported into the U.S.; whereas, domestically produced lesquerella oil could be used similarly to manufacture industrial products. Evaluation of existing pollen culture techniques developed for several other plant species led to a system that reliably predicts pollen developmental stage in lesquerella. However, the attempted variations on existing protocols proved ineffective at promoting lesquerella pollen growth in culture. These results indicate that pollen culture techniques for lesquerella will require further refinement before this alternative method of crop improvement can be utilized. Scientists pursuing future lesquerella breeding trials will benefit from these findings.

Technical Abstract: Obtaining homozygous lines from highly out-crossing, self-incompatible species requires multiple generations of time-consuming and frequently failed self crosses. The utilization of microspore embryogenesis can generate purely homozygous lines rapidly and efficiently, thus allowing for mutational breeding and selection of beneficial crop traits. The present study was initiated to determine if an effective androgenic culture protocol could be established for a new oilseed crop in the Brassicaceae family, Lesquerella fendleri (Gray) Wats. Anthers and isolated microspores of lesquerella were cultured in vitro using modifications of existing androgenic culture protocols developed for Brassica species. Modifications included the sampling of floral buds varying in size from 1.77 to 5.59 mm in length, using liquid #-NLN and Gamborg B5 media, varying sucrose concentrations of 3, 6, 9, 10, 12, 13 or 14% w/v, using colchicine concentrations of 0, 10, 25, 31, 50 or 63 #M,6-benzyladenine (BA) concentrations of 0.2, 1.1, 1.3, 2.2, 4.4 or 5.6 #M,1-naphthaleneacetic acid (NAA) concentrations of 0.5, 1.1, 1.6, 2.1 or 2.7 #M and using plate incubation temperatures of 28, 30, 32 or 35 C. A system that reliably predicts microspore developmental stage based on floral bud morphometrics, specifically floral bud and mean petal length was developed. Existing anther culture protocols for Brassicaceae and their variations proved ineffective at producing haploid lesquerella embryos. Likewise, isolated microspores cultured from 12 greenhouse grown lesquerella lines in 1997 and 1998 yielded undesirable diploid calli and no microspore-derived embryos. These results indicated that microspore culture techniques for lesquerella require further refinement before androgenic progenies can be obtained.