Mobilization of Nitrogen and Phosphorus from Endosperm

Proteinase activities in quiescent and germinating seeds of xHaynaldoticum sardoum

“…Similar results were found in germinating maize (Harvey and Oaks 1974a) and in various organs of wheat during ontogenesis (Waters et al 1980), In xH, sardoum extracts higher ratios were obtained with pool III and pool II acting on gliadin than with hemoglobin as substrate. These results suggest that both hemoglobin and gliadin were mainly hydrolyzed by endopeptidases (Dalling and Bhalla 1984).…”

“…Low proteinase activities have been detected in quies-although they may reasonably function as initiator procent seeds of several plants, Doi et al, (1980) described teinases (Mikola 1983), However, before definite conthe presence of an aspartic proteinase inhibited by pep-elusions can be drawn in this regard more information is statin A in rice endosperms. Scots pine seeds showed a required about their localization and regulation in vivo moderate amount of a proteinase activity, which was (Dalling and Bhalla 1984), inhibited by pepstatin A (90%) and p-hydroxymercuri-During germination the proteinase activity rapidly benzoate (10%); lower activities in the hydrolysis of increases; this is usually associated with the mobilicasein (pH 5,4 and 7.0) were also detected (Salmia zation of protein reserves and may indicate the partici-1981b), Kidney beans contain at least 2 proteinases, one pation of the proteinases in the degradation process, active against casein at pH 7,0 and 5,4, the other acting These enzymes are not present in dry seeds, appear on hemoglobin at pH 3,7 and sensitive to inhibition by after 2 or more days of germination and are cysteine pepstatin A (Mikkonen 1986), However, the low activ-proteinases (Shutov and Vaintraub 1987), They have been found in germinating seeds of dicotyledons, monocotyledons and gymnosperms and. therefore, seem to be characteristic of all Spermatophyta (Shutov and Vaintraub 1987), Despite the great number of studies on reserve protein mobilization, knowledge about the specificity of proteinases present in quiescent and germinating seeds is limited (Mikola 1983); and some confusion has been caused by the use of exogenous proteins in vitro only, which may not reflect proteolytic activity of relevance in vivo (Rastogi andOaks 1986.…”

Histochemical aspects of reserves mobilization of Caesalpinia peltophoroides (Leguminosae) seeds during germination and seedlings early growth

“…The presence of globular inclusion characteristic in the protein bodies corresponds to phytate, the main phosphorous reserve in addition to other possible inclusions (DALLING and BHALLA, 1984). Histochemical results reported by Irving (1984) and Otegui et al (1998) characterized the presence of inclusions of the phytin complex in protein bodies.…”

“…These XP positive corpuscles were vacuolated structures that accumulated reserve protein in the seeds and are called protein bodies by various authors (TROMBS, 1967;DALLING and BHALLA, 1984;VIDAL and PIMENTEL, 1985;SILVA et al, 1997;MÜNTZ et al, 2001;BUCKERIDGE et al, 2004).…”

Natural variation in iron use efficiency and mineral remobilization in cucumber (Cucumis sativus)

“…Other mineral elements can also be remobilized from vegetative or seed covering tissues (Garnett and Graham 2005;Gregersen et al 2008;MasclauxDaubresse et al 2010;Naeve and Shibles 2005;Suna-rpi and Anderson 1996;Waters and Sankaran 2011). Likewise, cotyledons and endosperm tissues can be important sources of remobilized minerals for developing seedling growth, such as S (Sunarpi and Anderson 1995), Zn (Sudia and Green 1972), Fe (Ambler and Brown 1974;Tiffin et al 1973), N and P (Bewley and Black 1985;Dalling and Bhalla 1984;Mayer and Poljakoff-Mayber 1982). An increased understanding of genes involved in remobilization from seed reserves or vegetative tissues could lead to strategies to increase internal Fe use efficiency.…”