Symptoms Of An Infected Onion Plant Case Study

Fig. ( 1 ): Symptoms of an infected onion plants with IYSV in a commercial onion field and greenhouse . Fig. ( 1 -A,B,C,D ) : IYSV Symptoms development in the field showing chlorotic, elongate ringed lesions on leaves and tip dieback (A) , Straw-colored, lenticular or spindle -shaped lesions (B ), chlorotic, spindle-shaped lesions on onion leaf and spindle to diamond shaped lesions on the flower scapes (C,D) . symptoms of IYSV in the greenhouse transmitted with virulifierous Thrips tabaci showing the typical symptoms of infected plants.

Fig.( 2 ): Showing symptoms on different diagnostic hosts; ( A): Chenopodium quinoa showing chlorotic local lesion, (B): Chenopodium murale showing chlorotic local lesions, (C) : D. stramonium
Their values decreased in different treatments with antiviral compounds (Fig.4). The decreasing values of MDA in treatment with jojoba seeds extract was lower than treatment with riboflavin, the decreasing values of TBARS at 100, 500, and 1000 µg/ml jojoba seeds extract were 30.22, 24.44 and 18.19 µmol and in riboflavin treatment at 0.5 ,1 and 2.5 mM the decreasing values were 31.53, 27.79 and 35.11 µ mol, respectively compared to infected plants (positive control ). At the same time under viral infection glutathione content was increased compared with healthy plants which their values were (3.64 and 2.41 µmol ) respectively. These values increased in different treatments with jojoba seeds extract and riboflavin which recorded (6.29 and 5.83 µmol) in jojoba seeds extract at 1000 µg/ml and riboflavin at 1mM respectively. To counteract the toxicity of ROS in response to the variety of stress antioxidant defiance system will be activated in plants. Thus the antioxidant and resistance enzymes peroxidase (POD), superoxide dismutase (SOD), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were extracted from onion leaves assayed as specific activities. Data in (Fig.4) indicated that infection with IYSV increase
(B,C,D,E ,F ) Electron micrographs representing the effect of IYSV-infection on onion cell organelles compared with those of healthy cells. (B): Mesophyll cell of healthy onion leaf with normal shape nucleus(Nu),Nucleolus (NO) and number of chloroplasts (arrow), (C): Cell of IYSV -infected leaf showing large size of the nucleus (Nu),dense aggregation and segmented chromatin (Ch) ; (D): Lyses of rough endoplasmic reticulum(rER) and nuclear membrane(NM ) producing many small vacuoles(V) ; (E): Elongated nucleus and lyses of mitochondria(M) and chloroplast (C) of infected cell and ( f ): Showing virus like particles (VLP) in cytoplasm adjacent plasma membrane (PM)