3.2.8 Corn and grain plants

Publisher Summary The wheat curl mite (WCM), Aceria tulipae, is the only known vector of the economically important and widespread wheat streak mosaic rymovirus (WSMV). Aceria tulipae is known as the WCM because of the effect its feeding has on young wheat plants. These mites begin the colonization of a wheat plant by moving inside the whorl of a developing leaf. They occupy the adaxial surface, feeding among veins in the grooved sections. This area of the leaf is comprised of thin-walled epidermal tissue known as “bulliform cells.” The unrolling of growing leaves occurs when bulliform cells enlarge. Consequently, because mites feed exclusively upon these cells, they effectively prevent the actively growing leaf from uncurling. As the curled leaf continues to grow, the subsequent leaf is trapped inside causing a syndrome of curled, looped, and trapped leaves to ensue. The morphologically altered plant provides the mites with the humid conditions that are necessary for survival and continued reproduction. The most promising means of control of WSMV is through resistance to the virus and/or vector. Wide crosses using other grass species to move resistance into wheat now may be accelerated by the use of modern recombinant strategies.