Photosynthetic performance of Jatropha curcas fruits

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<ul><li><p>cy Vnica</p><p>Chlorophyll a uorescenceJatropha curcasFruit photosynthesisSeed respirationVapour pressure decit (VPD)</p><p>ndeer (serin</p><p>Fig. 1n Centsubtro</p><p>perform photosynthetic CO2 assimilation. Fruit photosynthesis,either manifested as net photosynthesis or internal CO2 rexationis regarded as an important strategy of additional carbon-acquisition. Chlorophyllous reproductive structures could derive</p><p>increases assimilate partitioning towards lipids. Thus, A in fruitsoccurs under a specic microenvironment never encountered byleaves. Moreover, the metabolic status of fruits is quite different toleaves, as fruits are sinks for both carbon and chemical energy [15].Lytovchenko et al. [17] suggest that fruit photosynthesis is notnecessary for fruit energy metabolism or development, but isessential for properly timed seed development and may thereforeconfer an advantage under conditions of stress.</p><p>* Corresponding author. Tel.: 91 522 2297928; fax: 91 522 2205847.</p><p>Contents lists available at</p><p>Plant Physiology a</p><p>els</p><p>Plant Physiology and Biochemistry 52 (2012) 66e76E-mail address: pashirke@nbri.res.in (P.A. Shirke).The seed oil of J. curcas has long been used around the world asa source of lamp oil. Recently, it has attracted global attention, sinceJ. curcas is considered to be one of the most prominent species forbiofuel production the world over. It has been claimed that thatJ. curcas has few pests and diseases and grows under a wide rangeof environmental conditions [21,23].</p><p>In addition to the green leaves, commonly considered as theprimary sources of photosynthate production, higher plants canpotentially use almost all vegetative and reproductive structures to</p><p>extremely high CO2 concentration, and alleviate the adverse effectsof hypoxia due to a very low partial pressure of O2 because themovement of oxygen through the fruit tissues cannot keep pacewith the rate of oxygen consumption [5,10,15,22]. Rolletschek et al.[25] have also shown in developing soybean seeds that illuminationof seeds causes photosynthetic release of signicant amounts of O2.Under internal hypoxia occurring due to high respiration rates ofthe seeds, this O2 is instantly used for respiration which, in turn,elevates the energy supply. Finally, this affects metabolic uxes and1. Introduction</p><p>Jatropha curcas (SupplementaryEuphorbiaceae family, originated ithrives in many parts of tropics and0981-9428/$ e see front matter 2011 Elsevier Masdoi:10.1016/j.plaphy.2011.11.008photosynthetic performance of jatropha fruits. Immature fruits showed high light saturating point ofaround 2000 mmol m2 s1. High VPD did not show an adverse effect on the fruit A. Stomatalconductance (gs) showed an inverse behaviour to increasing VPD, however, transpiration (E) was notrestricted by the increasing VPD in both seasons. During winter in absence of leaves on the jatrophatree the fruits along with the bark contributes maximum towards photoassimilation. Dark respirationrates (Rd) monitored in fruit coat and seeds independently, showed maximum Rd in seeds of maturefruit and these were about ve times more than its fruit coat, reecting the higher energy requirementof the developing fruit during maximum oil synthesis stage. Photosynthesis and uorescenceparameters studied indicate that young jatropha fruits are photosynthetically as efcient as its leavesand play a paramount role in scavenging the high concentration of CO2 generated by the fruit duringrespiration.</p><p> 2011 Elsevier Masson SAS. All rights reserved.</p><p>A), a member of theral America, but nowpics of Asia and Africa.</p><p>up to 60% of their total carbon requirement from own CO2 xation[1]. In non-foliar plant parts such as fruits and stem, A is believed toassist in the assimilation of respiratory CO2, thus compensating forcarbon loss [3,7,22]. Another plausible function is related to the factthat, A may additionally help to avoid acidication because ofKeywords:Bark photosynthesismade in both winter and summer fruits in response to light, temperature and vapour pressure decit(VPD) under controlled conditions to assess the inuence of these environmental factors on thepha fruits was studied at three developmental stages, immature, mature and ripe fruits. Studies wereResearch article</p><p>Photosynthetic performance of Jatropha</p><p>Sanjay Ranjan, Ruchi Singh, Devendra K. Soni, UdaPlant Physiology Division, Council of Scientic and Industrial Research e National Bota</p><p>a r t i c l e i n f o</p><p>Article history:Received 15 September 2011Accepted 19 November 2011Available online 28 November 2011</p><p>a b s t r a c t</p><p>Jatropha curcas (L.) trees uonce during autumnewintand already shedding. Thethe leaves have formed du</p><p>journal homepage: www.son SAS. All rights reserved.urcas fruits</p><p>. Pathre, Pramod A. Shirke*</p><p>l Research Institute, Rana Pratap Marg, Lucknow 226 001, India</p><p>r north Indian conditions (Lucknow) produce fruits in two major ushes,OctobereDecember). The leaves at this time are at the senescence stagescond ush of fruit setting occurs during the summer (AprileJune) afterg spring (MarcheApril). Photosynthetic performance of detached jatro-</p><p>SciVerse ScienceDirect</p><p>nd Biochemistry</p><p>evier .com/locate/plaphy</p></li><li><p>Table 1Characteristics of various parameters in J. curcas fruits: Themean fruit weight and surface area in J. curcas fruits produced inwinter and summer. The dark respiration rates (Rd)measured in the fruit coat and the seeds at 25 C. The chlorophyll (Chl) content, intrinsic photosynthetic efciency of PS II, (Fv/Fm) in dark adapted fruits and the stomatacharacteristics of J. curcas fruits produced in summer during different developmental stages. Data represent the means SD of 8e10 samples. T-tests were performed for pairsof corresponding values between (meanwinter fruit weight andmean summer fruit weight, meanwinter fruit area andmean summer fruit area) and for rest of the parametersbetween (immature fruit and mature fruit, ripe fruit); signicantly different values are indicated with asterisks (P 0.001) and not signicant as n.s (P&gt;0.001).</p><p>Parameters Immature fruit (mean SD) Mature fruit (mean SD) Ripe fruit (mean SD)Mean winter fruit weight (g) 3.88 0.59 16.38 2.14 12.48 1.53Mean winter fruit area (cm2) 13.22 1.44 31.85 4.43 26.23 2.43Mean summer fruit weight (g) 2.69 0.35* 7.63 0.71* 5.3 1.26*Mean summer fruit area (cm2) 11.63 0.61n.s. 20.40 0.86n.s. 16.49 1.91*Fruit Coat Rd (nmol s1 g1 FW) 3.0 0.48 2.10 0.20n.s. 1.26 0.30n.s.Seed Rd (nmol s1 g1 FW) 4.37 1.33 10.5 2.20n.s. 1.2 0.05n.s.Chl (mg g1 FW) 84.5 8.2 72.4 6.2* 45.15 3.2*Chl a/b ratio 2.93 0.14 3.24 0.18* 3.0 0.41n.s.Fv/Fm 0.79 0.019 0.77 0.042n.s. 0.63 0.06*Stomata density (mm2) 72.22 10.93 66.79 6.39n.s. 65.0 5.92n.s.Guard cell length (mm) 15.03 0.76 18.03 0.70* 16.08 0.41n.s.Guard cell width (mm) 4.17 0.28 4.60 0.20n.s. 4.17 0.17n.s.</p><p>S. Ranjan et al. / Plant Physiology and Biochemistry 52 (2012) 66e76 67Under north Indian climatic conditions (Lucknow), J. curcasshows major fruit setting during its two ushes in a year. Duringspring in early March new leaves ush followed by ower initiationand subsequently fruit setting during AprileJune, which are thesummer months. The second ush of fruiting sets in October andfruiting occurs until December. During this winter period the leavessenesce and leaf fall occurs in J. curcas trees. The major photosyn-thetic tissues in J. curcas during this period are the fruits and thebark.</p><p>In leaves under the natural conditions the major environmentalfactors that inuence the gas-exchange parameters are light,temperature and vapour pressure decit (VPD) [28]. It has beenshown in several plants that there is a reduction in steady-statestomatal conductance with an increase in VPD [20,6]. This isinterpreted as a means by which plants can minimize water loss[28,30]. Hence, we were interested to understand as to do theseenvironmental factors also inuence gas exchange in the jatrophafruits? We have studied the response of temperature and VPD onthe gas-exchange characteristics of jatropha fruits in winter andsummer during their developmental stages. The light responsestudies and net photosynthesis rate versus internal CO2 concen-tration (ACi) curves in developing jatropha fruits were carried out inthewinter fruits. The leaf photosynthetic characteristic was studiedin summer and the contribution of bark photosynthesis wasstudied in the winter.Fig. 1. J. curcas fruits studied at different developmental stages. Immature stage fruits wer17days (B) and ripe stage fruits were collected between 30 and 32 days (C) after anthesis.2. Results and discussion</p><p>2.1. Fruit development, stomata and chlorophyll content in J. curcasfruit</p><p>The jatropha fruits (Supplementary Fig. 1C) were studied fortheir developmental size during the two major fruiting periods ofwinter and summer (Table 1). The fully developed mature fruitsformed in winter were more than 1.5 folds in surface area and 2times more inweight than the fruits produced in summer (Table 1).The stomatal density, length and width of guard cells wereobserved in the peels of immature, mature and the ripe fruits(Fig. 1), which were collected on 8e10 days, 15e17 days and 30e32days after anthesis in case of immature, mature and ripe stagesrespectively. The density was higher in the immature fruits at 72stomata mm2 as compared to the mature and ripe fruits where itwas 67 and 65 stomata mm2 respectively however, these differ-ences were not statistically signicant. The size of stomata wassmaller in immature fruits than in the mature fruits (Table 1). Thenumber of stomata is set at anthesis and remains constant, whilethe stomatal frequency decreases as the fruit surface expands [3].</p><p>Chlorophyll content was maximum in the immature fruits and itwas just around 50% in ripe fruits due to the degradation of chlo-rophyll (Table 1). The fruit chlorophyll amounted only about 17% ofthe leaf chlorophyll content (Table 2). However, the chl a/b ratioe collected between 8 and 10 days (A), mature fruits were collected between 15 and</p></li><li><p>16 mmol m s in ripe fruit. Maximum assimilation rate (Amax)2 1</p><p>A (</p><p>m</p><p>-2</p><p>0</p><p>2</p><p>E (m</p><p>mo</p><p>l m</p><p>-2</p><p> s</p><p>-1</p><p>)</p><p>0.0</p><p>0.3</p><p>0.6</p><p>0.9</p><p>1.2</p><p>1.5</p><p>1.8</p><p>gs (m</p><p>mo</p><p>l m</p><p>-2</p><p> s</p><p>-1</p><p>)</p><p>0</p><p>20</p><p>40</p><p>60</p><p>80</p><p>100</p><p>mo</p><p>l m</p><p>ol-</p><p>1</p><p>)</p><p>400</p><p>600</p><p>800</p><p>C</p><p>B</p><p>D</p><p>andwas 9.8 (1.55), 5.0 (0.84) and 0.64 (0.13) mmol m s inimmature, mature and ripe fruits respectively. The apparentquantum use efciency (AQE) was 0.007 mol CO2 mol1 incidentphotosynthetic photon ux density (PPFD) in all three stages ofwas around 3.0 in fruits of all three stages and was comparable toleaf chl a/b ratio of 3.35 (Tables 1 and 2). Similar chlorophyll chl a/b ratio has been observed in other fruits [2,17].</p><p>2.2. Gas-exchange and uorescence in response to light</p><p>Detached jatropha fruits during the different developmentalstages (Fig.1) showed a vast variation in their light response (Fig. 2).The immature stage fruit showed a light saturation point (ALSP) of2155 (340) mmol m2 s1, while the mature and ripe showed 1108(185) and 144 (30) mmol m2 s1 respectively. The lightcompensation point (ALCP) was 4.0 (0.65) mmol mmol m2 s1 inimmature and 64 (10.7) mmol m2 s1 in mature fruits and was</p><p>2 1</p><p>Table 2Gas exchange characteristics (net photosynthesis, A; transpiration, E and stomatalconductance, gs), Chl uorescence characteristics (electron transport rates, ETR;effective quantum yield of PSII, FPSII; photochemical quenching, qP; non-photochemical quenching, qN and intrinsic photosynthetic efciency of PS II, Fv/Fm) and chlorophyll (Chl) content of young mature leaves of J. curcas under ambientconditions of photosynthetic photon ux density (PPFD), leaf temperature (LT) andvapour pressure decit (VPD) in summer. Data represent the means SD of veindependent experiments.</p><p>Parameters Leaf, in summer (mean SD)PPFD (mmol m2 s1) 1075 85LT (C) 34.9 0.68VPD (KPa) 2.05 0.2Maximal A (mmol m2 s1) 21.62 1.52E (mmol m2 s1) 5.5 0.48gs (mmol m2 s1) 270 28Maximal ETR (mmol m2 s1) 165 3.5FPSII 0.361 0.054qP 0.641 0.055qN 0.71 0.029Fv/Fm (dark adapted) 0.828 0.022Chlorophyll (mg g1 FW) 488 71Chlorophyll a/b ratio 3.35 0.14</p><p>S. Ranjan et al. / Plant Physiology68fruits (Fig. 2A), fruits in general have a very low AQE as compared toleaf [2]. The developing immature fruit showed a light compensa-tion point of 4.0 mmol m2 s1 indicating a capacity to utilize evenextremely low light for its A. Immature fruits also showed a veryhigh light saturation point (ALSP) of 2155 mmol m2 s1 and the ALSPin mature fruit was above 1100 mmol m2 s1, these were very highin comparison to ALSP in leaves of most of the C3 plants [16] or infruits of Cinnamomum camphora, which showed ALCP of around100e400 mmol m2 s1 [14]. The high ALSP is due to the high CO2availability for photosynthesis produced due to the high respirationin jatropha fruits. A similar high photosynthesis at high lightintensity is also observed in tomato fruits [17].</p><p>The rate of transpiration (E) showed an increasing trend withincrease in PPFD in immature fruits even at 2000 mmol m2 s1</p><p>PPFD (Fig.1B). E and the gs weremore or less constant at all the lightlevels in the mature and ripe stages of fruits studied (Fig. 2B, C). Theinternal CO2 concentration (Ci) showed a decreasing trend withincrease in PPFD and A in immature and mature fruits (Fig. 2D). Inripe fruits where the A was very low at around 0.5 mmol m2 s1</p><p>(Fig. 2A) the Ci did not show much variation and was around600 mmol mol1 (Fig. 2D).</p><p>The effective quantum yield of PSII (FPSII) indicates the energyutilisation by the photosynthetic tissue, as it measures theproportion of the photos absorbed by chlorophyll associated withol m</p><p>-2</p><p> s</p><p>-1</p><p>)</p><p>4</p><p>6</p><p>8</p><p>10A</p><p>Biochemistry 52 (2012) 66e76PSII that is used in the photochemistry and thus indicates overallphotosynthesis [11]. The FPSII values observed at zero PPFD wasabove 0.8 in immature and mature fruits, while it was 0.66 in ripefruit (Fig. 3A). FPSII decreased with increase in PPFD in all threestages of fruits however, the decrease was drastic in ripe fruitsfollowed by mature and immature fruits respectively (Fig. 3A). Theelectron transport rates (ETR) in immature fruits (Fig. 3B) werecomparative to the rates of maximal ETR in leaves of jatropha</p><p>PPFD (mol m-2 </p><p>s-1</p><p>)</p><p>0 400 800 1200 1600 2000</p><p>Ci (</p><p>0</p><p>200</p><p>Fig. 2. Photosynthetic light response curve in fruits of jatropha, (A). The concurrenttranspiration rates, E (B), stomatal conductance, gs (C) and internal CO2 concentration,Ci (D), in immature (C), mature (-) and ripe (:) fruits. Measurements were madebetween 8:00 and 11:00 h at a fruit surface temperature of 28e29 C and VPD wasmaintained below 2.0 kPa. Data represent the means SD of ve independentexperiments. The linear and quadratic terms for the polynomial regressions for A underincreasing photosynthetic photon ux density (PPFD) was signicant at P &lt; 0. 0001and r2 values were 0.99 for immature and mature and 0.98 for ripe fruits.</p></li><li><p>antu(:)</p><p>andA</p><p>C</p><p>Fig. 3. Fluorescence parameters in response to light in fruits of jatropha. The effective qu(C) and non-photochemical quenching, q (D), in immatur...</p></li></ul>