The investigation dealt with starch accumulation in four species of Cuscuta {CiLsciita cnmpcvtri.s, (.. indecora, C. phmiflorit and (.. refh'xn), a leafy mistletoe {Driulrophthne falcatn] and a chloropbyll-lackiog root parasite {Orobanche acgypti(fca}. The highest content of .starcti occurred In O. acgypliaca, witb a maximum of 45 per cent of dry weigbt. Starch in Cuscuta filaments and mistletoe leaves showed a maximum of about 10 per cent of dry weight. The starch content varied along the length of the Cuscula vine, with a maximum in the apical region. Orobanche hati a higher starcli content when it was still submerged than it was fully developed. Cuscuta vines did not show any marked diurnal alteration in tbe starch content. The content of etbanol-soluble carbohydrate was only a tenth of the starch in Orobancbe, but was relatively bigber in tbe other parasites. Tbe neutral sugars in Cnscuta filaments were sucrose and glucose, whereas fructose was also present in mistletoe and Orobanche. Raffinose and stachyose were absent or present only ill traces in parasite tissue. Starcli granules from Cuscuta and Orobanche bad .\l)P(i/UI)P(i-starcb synthetase activity and homogenates starch phospborylase activity. Tbe former enzyme appeared to be responsible for synthesis of starch and the latter for utilization. Tbe four different species of Cuscnta, growing on alfalfa, had more or less the same activity of starcb syntbetase and also of i)hospborylase activity. Hosts infected by Cuscuta bad significantly less starch per plant tlian tbe controls. A characteristic feature of invasion by Cuscuta and Orobanche was increased phos-|»borylase activity in the bost tissues. The protein content of the tissues of Cuscuta and Orobanche was of a lower level tban that of tbe bost shoot system or foliage, indicating that tbe parasite differed from the host in having a Iiigher carbon (of starch) to nitrogen (of protein) ratio.;i. '> Fhysiol. Plant., 21, l')'iS [525] Phyaiol. riant.. 21,1968

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