ARS | Publication request: Beta vulgaris L. serine proteinase inhibitor gene expression correlates to insect pest resistance in sugar beet

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2012
Publication Date: April 7, 2012
Citation: Savic, J., Smigocki, A.C. 2012. Beta vulgaris L. serine proteinase inhibitor gene expression correlates to insect pest resistance in sugar beet. Euphytica. 186:1-12.

Interpretive Summary: Disease and pest problems are responsible for decreases in production of sugar from sugar beet. Over 26 million tons of sugar beet valued at over 1.2 billion dollars are produced each year in the U.S. One of the most devastating insect pests of sugar beet is the sugar beet root maggot that is currently found in more than half of all U.S. sugar beet fields. To gain a better understanding of how plants protect themselves from insect attack, in our past studies we identified sugar beet genes that respond to sugar beet root maggot infestation in root maggot-susceptible and moderately resistant sugar beet varieties. One of the genes (BvSTI) was selected for further analysis in several varieties of sugar beet that are known to be partially resistant to the sugar beet root maggot as compared to a susceptible breeding line (F1010). The gene was found to be more active in the resistant as compared to the susceptible variety. Both mechanical damage and insect feeding induced the activity of the BvSTI gene. We conclude that the BvSTI gene can be used in a biotechnological approach or breeding programs selecting for improved insect resistance. Scientists will use this information to develop safer approaches of insect control in plants and this will lead to an increase in yields and reduction of chemical pesticide usage.

Technical Abstract: Analyzing genes that can be used for improving sugar beet resistance to the sugar beet root maggot (SBRM, Tetanops myopaeformis Roder), one of the most destructive insect pests of sugar beet in North America, was a major goal in our investigation. We report on the expression patterns of a sugar beet trypsin proteinase inhibitor gene, BvSTI, in F1016, F1015 and UT-8 sugar beet germplasm with moderate levels of SBRM resistance as compared to a susceptible F1010 breeding line. Expression in roots and leaves was analyzed at the mRNA and protein level in response to mechanical wounding or fall armyworm (FAW, Helicoverpa spodoptera Hübner) feeding. In general, higher base line and wound induced levels of BvSTI gene transcript accumulation were observed in all of the analyzed resistant lines as compared to the susceptible line. Accumulation of BvSTI transcripts in tissues attacked by FAW was delayed in comparison to the response observed following mechanical wounding. Using in gel assays, numerous trypsin inhibitor activities were detected in F1016 and F1010 mechanically wounded tissues. BvSTI specific antibodies cross-reacted with 30 kDa proteins in leaves but not roots of either line. We conclude that the BvSTI gene could prove to be useful in a biotechnological approach or molecular breeding programs selecting for improved insect resistance.