Rice Genetics IV - IRRI books - International Rice Research Institute

(KIKEKLPG) in the carboxyl terminus. These proteins have been predicted to functionas chaperones (Dure 1992). Levels of the group 1 and 2 LEA proteins were significantlyhigher in vegetative tissues (such as roots) of salt- and drought-tolerantnontransgenic wheat, rice, and fingermillet genotypes than in those of sensitive genotypesunder salt- or drought-stress conditions or after the application of ABA on plants(Morris et al 1995, Moons et al 1995). Thus, the physiological characteristics of group1 and 2 LEA proteins support their function for providing cellular tolerance for conditionssuch as drought and salt.Two wheat genes, PMA80 and PMA1959, have been demonstrated to be responsiveto ABA and environmental stress. These two genes were cloned (Morris et al1995). To test the function of a group 2 and a group 1 LEA protein gene in transgenicrice, we constructed two plasmids. One plasmid, pJPM44, contains a wheat LEAgroup 2 protein (PMA80). The other, pJPM45, contains a wheat LEA group 1 protein(PMA1959). The structures of the two plasmids are shown in Figure 1. Both plasmidswere transferred into rice and fertile transgenic plants were obtained. Second-generationtransgenic plants were subjected to dehydration or salt stress. The results showedthat accumulation of either PMA80 or PMA1959 significantly increased the toleranceof transgenic rice plants for both dehydration stress and salinity stress (Table 1),as reflected by higher fresh and dry weight compared with NT (nontransformed) controlplants.Proline level and dehydration toleranceOverproduction of proline in transgenic rice plants was found to improve tolerancefor dehydration stress. Proline accumulation has been shown to be correlated withpJPM44Pst H, E B Pst Sma Pst Kpn Spe NotMAR1.0Act1(p)1.3PMA801.5Pin 3’1.035S/Bar/nos1.6MAR1.0 kbpJPM45Pst E B H Sma Pst Kpn Spe NotMAR1.0Act1(p)1.3PMA19590.8Pin 3’1.035S/Bar/nos1.6MAR1.0 kbFig. 1. Schematic diagram of plasmids pJPM44 and pJPM45. Act1(p) =rice actin1 promoter with actin1 first intron; PMA80 = a wheat cDNAcoding an LEA group 2 protein; PMA1959 = a wheat cDNA coding an LEAgroup 1 protein; Pin3’ = potato proteinase inhibitor II 3’ noncoding sequence;35S(p) = cauliflower mosaic virus 35S promoter; nos = 3’ terminatorfrom the nos gene; MAR = the tobacco Rb7 matrix attachmentregion. B = BamHI, E = EcoRI, H = HindIII.426 Cheng et al