Photosynthetic inorganic carbon utilization strategies and their ecological adaptability in aquatic plants
-
摘要:
水生维管植物经历了从陆生向水生的“回归”演化,这个过程伴随着周围环境的一系列巨大变化,尤其是水体中无机碳环境与陆生生境的差异赋予了水生植物光合无机碳利用策略与陆生植物截然不同的生态学意义。本文综述了以光合作用为核心的水生植物无机碳利用策略的特殊性和多样性,以及研究水生植物无机碳利用策略的意义,并展望了基于水生植物尤其是水鳖科的无机碳利用策略为核心的植物适应机制研究的优势,旨在为水生植物适应机制和适应性进化研究提供新的思考方向。
Abstract:Aquatic vascular plants have undergone an evolutionary transition from terrestrial to aquatic habitats, necessitating substantial adaptations to their surrounding environments. In particular, the different inorganic carbon environments between underwater and terrestrial habitats confer distinct ecological significance to the photosynthetic inorganic carbon utilization strategies of both plant types. This paper elucidates the particularity and diversity of inorganic carbon utilization strategies in aquatic plants and the significance of these studies. In addition, the potential advantages in studying plant adaptation mechanisms based on inorganic carbon utilization strategies in aquatic plants (especially Hydrocharitaceae) is analyzed. Overall, this paper aims to provide a novel perspective for studying the adaptative mechanisms and evolutionary processes of aquatic plants, as well as new directions for research in this field.
-
猕猴桃(Actinidia) 以其独特的风味,富含维生素 C (VC)、膳食纤维、多种矿物营养和清肠健胃等功效而得到消费者喜爱,已成为国内外重要水果种类之一[1]。猕猴桃为猕猴桃科猕猴桃属多年生落叶藤本植物,雌雄异株,于20世纪初才开始人工驯化,至今仅有 100余年历史。目前在栽培上,主要种植的品种为中华猕猴桃原变种(A. chinensis Planch. var. chinensis)和美味猕猴桃变种(A. chinensis Planch. var. deliciosa),兼有少量软枣猕猴桃(A. arguta (Sieb. & Zucc.) Planch. ex Miq.)和毛花猕猴桃(A. eriantha Benth.)[2]。依据果肉颜色不同,猕猴桃又被分为绿肉、黄肉、红肉(红心)3种类型,截至2020年底,三者种植面积分别约占总面积的50%、16%和32.5%,其中‘金艳’为黄肉型猕猴桃中种植面积最大的品种[2]。‘金艳’作为第一个商业种植的种间杂交黄肉品种,因其突出的果实综合商品性和丰产、稳产性,一经推出便得到迅速发展,截至2020年底,‘金艳’国内种植面积高达1.4 × 104 hm2[2, 3]。‘金艳’属于晚熟品种,在武汉地区10月下旬到11月初成熟,但为了满足市场多元化需求,需要成熟期更早的优质黄肉品种。 ‘金圆’是以‘金艳’为母本、中华猕猴桃为父本,从回交 F1代群体中选育出的中熟黄肉猕猴桃新品种,其果实成熟期比母本‘金艳’提早 3~4 周, 同时在果实风味品质及果形上有进一步提高[4]。
猕猴桃品种众多,国内主栽品种就高达10余种,如‘红阳’、‘东红’、‘徐香’、‘翠香’、‘金艳’等[2]。不同品种之间对配套栽培技术要求不同,不能盲目套用参照,必须根据每个品种各自的果实生长发育规律定制配套生产技术策略。目前,国内外已有大量关于猕猴桃果实生长发育规律的研究报道,如绿肉品种‘Hayward’[5, 6]、‘贵长’[7]和‘徐香’[8];黄肉品种‘Hort16A’[9]、‘金艳’[10, 11]、‘璞玉’[12]和‘金实1号’[13];红肉品种‘红阳’[14, 15]和‘红实2号’[16]等。研究发现,不同品种之间果实发育动态变化趋势虽有相似之处,但果实发育的快慢、时间长短等表现出一定的品种差异性。所以,应针对不同猕猴桃品种,在不同产区开展果实生长发育规律的研究,为制定适合特定新品种和产区的配套栽培技术提供理论依据。
目前,针对‘金圆’猕猴桃的研究仅有零星报道,涉及品种选育[4]和低温贮藏[17]等方面,有关其果实生长发育规律的研究尚未见报道。本文以丹江口和武汉两地生产的‘金圆’猕猴桃为研究对象,对果实生长发育过程中的品质指标进行动态监测,旨在探明‘金圆’果实的生长发育规律,并为‘金圆’新品种商业推广提供指导依据。
1. 材料与方法
1.1 植物材料
猕猴桃品种‘金圆’实验果实分别来自于湖北省丹江口市习家店镇猕猴桃示范基地(32°48′N,111°12′E)和国家猕猴桃种质资源圃(武汉)内(30°32′N,114°25′E)的成年果树。丹江口采样点年均气温7.7 ℃ ~ 16.0 ℃,年降水量750 ~ 900 mm;果园按照正常商业果园管理,疏花疏果,每年施基肥、促花肥、壮果肥3次。武汉果园海拔30 m,年均气温15.8 ℃ ~ 17.5 ℃,年均降水量1 269 mm;果园管理较为粗放,每年仅冬季修剪1次,并施基肥1次。两地‘金圆’株行距为2 m × 4 m,均为东西行向,大棚架式;园区均有自动喷灌设施。两地种植的‘金圆’果实均未套袋,均未使用膨大剂。选择生长健康且长势一致的‘金圆’果树10株(丹江口,2017年嫁接)或20株(武汉,2016年嫁接)用于果实生长发育监测实验。
1.2 实验方法
丹江口地区的‘金圆’生长发育调查从2021年5月22日(盛花期后16 d)开始,持续到2021年11月11日(盛花期后189 d);武汉地区的‘金圆’从2021年5月10日起,持续到2021年10月4日结束,即盛花期后15 ~ 162 d。实验分为树上固定果实生长监测和下树果实生长发育监测两个部分,前者选择30个固定的果实并编号,每周测量1次果实的纵、横、侧径以反映真实的果实生长趋势,这些果实一直挂在树上,并不采摘下来;后者则是每2周(生长初期)或每1周(生长中后期)采样并测试1次,每次随机采摘20个大小基本一致的健康果实用于生长发育指标检测,包括单果重、果实纵横侧径、硬度、果肉颜色、可溶性固形物、干物质、可溶性总糖和总酸(可滴定酸)等,其中前6个指标每个果实样本单独检测,测完之后每6 ~ 7个果实按1/4取样法取大致等量果肉混为1个样本,即每个时间点有3份样本,经液氮速冻后保存于−80 ℃,供后续的可溶性总糖和总酸含量测定。
1.3 指标测定
果重使用电子分析天平称重,数显游标卡尺测定果实纵横侧径(mm),果实体积大小按照(纵径 × 横径 × 侧径)/1 000公式进行计算[18](cm3)。果实生长速率为相邻两个检测时间点内果实纵横侧径的日变化。‘金圆’果实的预测单果重基于果实体积的线性回归进行计算,公式为:预测单果重 = 0.657 × 果实体积 − 1.804(丹江口)或预测单果重 = 0.635 × 果实体积 − 1.325(武汉),单位为g。硬度采用GS-15质地分析仪测定(GUSS,South Africa),在果实赤道位置削掉厚1 mm的果皮,采用7.9 mm直径探头测定,参考新西兰猕猴桃硬度测定标准设置仪器参数[19],触动临界值 50 g,前进速度 20 mm/s,后退速度 30 mm/s,测量速度5 mm/s,测量距离(插入深度)7.9 mm。仪器自动记录受到的最大力作为硬度值。每个果实测定两次,测定部位互为90°,取两者的平均值作为果实硬度,单位为牛顿力(N)。果肉颜色采用CR400色差计(Konica Minolta,Japan)测定,每个果实赤道位置削掉厚2 mm的果皮和果肉后测定,每个果实测量两次,测定部位互为90°,取两者色度角的平均值作为果肉颜色值,单位用°hue表示,其值范围为 0 ~ 180°,0°代表紫红色,90°代表黄色,180°代表绿色,当色度角 > 100°时,值越大越偏向于绿色。可溶性固形物含量采用折射仪测定(PAL-1,Atago),每个果实两端切下厚约1.5 ~ 2 cm的果片,各挤出果汁混合于折射仪样本凹槽内测定。干物质测定采用称重法,取果实赤道部位厚2 ~ 3 mm的横切片,经65 ℃烘干24 h后,称量烘干之后和之前的切片重量,两者比值的百分比即为干物质。果实中可溶性总糖的测定按照行标NY/T 2742-2015《水果及制品可溶性糖的测定3,5-二硝基水杨酸比色法》执行,以葡萄糖折算可溶性总糖含量,单位为%。果实中总酸(可滴定酸)含量的测定按照国标GB/T 12456-2008《食品中总酸的测定》执行并略作修改,采用自动滴定仪(HI931, Hanna Instrument)和0.1 mol/L 氢氧化钠(NaOH)滴定液将样本溶液pH值滴定到8.2为止,以柠檬酸折算总酸含量,单位为%。
1.4 数据分析
采用Origin 2021软件进行数据分析和绘图,结果以平均值 ± 标准误表示。相关性分析采用Pearson检验,相关系数为Pearson 相关系数。
2. 结果与分析
2.1 果实生长趋势
本研究根据丹江口和武汉两地‘金圆’树上固定果实的纵、横、侧径定期测量结果,反映果实真实客观的生长变化趋势。结果表明,两地产的‘金圆’果实的纵、横、侧径均表现出先快后慢然后趋于平稳的生长趋势,其中丹江口果实的纵横侧径明显大于武汉果实(图1:A)。可反映果实“高矮”的果形指数(纵径 / 横径比值)在生长早期即盛花期后 30 d内均轻微增加,然后分别稳定在1.1(丹江口)和1.0(武汉)水平上,而可以反映果实横切面是圆是扁的果形指数(横径 / 侧径比值)在整个发育监测时期内均稳定在1.0水平左右(图1:B)。说明‘金圆’果实在生长早期内纵向生长速度大于横向生长速度,果实生长后期两者生长速度相似,趋于稳定;同时也说明‘金圆’果实横切面始终都保持圆形。两地生产的‘金圆’果实在生长监测期内均有一个生长高峰和2 ~ 3个小高峰,表明果实生长最快的阶段发生在盛花期后35 d内,主要生长阶段在盛花期后60 d内,且在生长中后期(盛花期后110 d附近)存在一个明显的小高峰(图1:C)。两地的果实体积变化趋势和纵横侧径变化趋势高度相似,其中丹江口果实明显大于武汉果实,且在盛花期后60 d时均接近于最终体积的75% ~ 80%(图1:D)。另外,从下树后果实的生长趋势来看,两地产的‘金圆’果实单果重和果实体积均随生长时间的推移而先快速增加,后大致趋于平稳;其中丹江口果实重量和体积明显大于武汉果实(图1:E、F);在盛花期后70 d内,果实重量和体积增加最快;在盛花期100 d后丹江口果实重量基本稳定在95 ~ 115 g,武汉则稳定在70 ~ 80 g(图1:E、F)。
图 1 丹江口和武汉生长的‘金圆’果实生长趋势A ~ D为树上固定果实的生长趋势。A:果实纵横侧径;B:果形指数;C:纵横侧径的生长速率;D:果实体积;E、F:下树后果实的生长趋势(E为单果重,F为果实体积)。Figure 1. Growth trends of ‘Jinyuan’ fruit on and off vine grown in Danjiangkou (DJK) and Wuhan (WH) orchardsA–D indicate growth of fruit fixed on vine during whole period. A: Length of fruit vertical diameter (VD), horizontal diameter (HD), and lateral diameter (LD); B: Fruit shape index based on ratio of VD/HD and HD/LD; C: Growth rates of VD, HD, and LD; D: Fruit size based on VD, HD, and LD data. E and F indicate growth of fruit detached from vine during monitoring period (E, fresh weight of single fruit; F, fruit volume calculated from VD, HD, and LD data).2.2 果实重量与体积的相关性分析
通过定期对采摘下来的‘金圆’果实进行单果重和体积(基于果实纵横侧径)测定,发现丹江口和武汉产的果实单果重与体积高度正相关,呈线性关系,皮尔逊(Pearson)R2值分别高达0.989和0.988(图2:A、B)。利用其线性回归方程,对两地生长的固定果实进行了单果重预测分析。结果表明,两地产的果实的预测单果重与果实体积变化趋势高度相似,均表现出先快后慢然后趋于平稳的生长趋势,其中丹江口果实的预测单果重稳定在近100 g的最终水平上,武汉果实的预测单果重则维持在最大值75 g左右,且盛花期后70 d时果实预测单果重达到最终稳定水平的近80%(图2:C、D)。
图 2 ‘金圆’果实重量与果实体积的相关性分析及预测单果重变化A、B:丹江口(A)和武汉(B)生产的‘金圆’果实重量与体积的相关性分析; C、D:丹江口(C)和武汉(D)生产的‘金圆’在生长期内的预测单果重变化。单果重的预测基于图1中固定在树上的果实体积数据。Figure 2. Correlation analysis of fruit weight and volume and change in predicted weight of ‘Jinyuan’ fruitA, B: Correlation analysis of fruit weight and volume of ‘Jinyuan’ produced in Danjiangkou (A) and Wuhan orchards (B); C, D: Change in predicted weight of ‘Jinyuan’ fruit on vines during growth period in Danjiangkou (C) and Wuhan (D) orchards. Volume data of fruit fixed on vines in Fig. 1 were used to predict fruit weight.2.3 果实成熟度变化
对丹江口和武汉两地产的‘金圆’果实定期采收,并测量果实成熟度指标,包括干物质、硬度、果肉颜色和可溶性固形物等。总的来说,这4个指标在丹江口和武汉产的‘金圆’生长期内均表现出高度相似的变化趋势,尤其是干物质、果肉颜色和可溶性固形物,不仅变化趋势相似,且其值在同一时间点上也相近,但是硬度在同一时间点上有较大的差异(图3)。丹江口和武汉产的果实干物质含量均呈先小幅下降然后逐渐上升的趋势,至盛花期后135 d时分别达到17.0%和15.7%,进入稳定平台期;经过3周后又小幅提升,至盛花期后189 d时,丹江口果实干物质提升至18.1%(图3:A)。果实硬度均表现出逐渐下降的趋势,盛花期后168 d时丹江口果实硬度急剧下降;另外,在整个生长监测期内,武汉产果实硬度高于丹江口(图3:B)。果肉颜色从盛花期后120 d时的110 °hue逐渐下降至盛花期后155 d时的103 °hue附近,达到黄肉猕猴桃品种对果肉颜色的采收要求,至盛花期后175 d时继续下降至97 °hue附近,然后稳定在这一水平上(图3:C)。可溶性固形物含量从盛花期后127 d开始快速上升,至盛花期后148 d时达到8%,然后继续上升至15.5%(盛花期后189 d时)(图3:D)。
利用在果实采收前近1个月到生长监测结束时内的每个果实的成熟度指标数据,分析了它们之间的相关性(图4)。果肉颜色与可溶性固形物之间存在较高的负相关性(丹江口和武汉Pearson r值分别为−0.93和−0.89),但与干物质或与硬度之间的相关性较低(r均在−0.52以下),并且干物质、硬度和可溶性固形物之间并没有较强的相关性存在。另外,果重与干物质之间也没有发现较好的相关性存在(数据未显示)。然而,如果单果重和干物质含量数据扩展到整个生长发育时期,那么它们之间的相关系数可以提高到0.83(丹江口)或0.71(武汉)(数据未显示)。
图 4 丹江口和武汉产的‘金圆’果实成熟度指标之间的相关性系数供相关性分析的各成熟度指标数据来源于果实近成熟期内的数据,丹江口为盛花期后127 ~ 189 d内(n = 209),武汉为盛花期后120 ~ 162 d内(n = 140)。Figure 4. Correlation coefficients among maturity indices of ‘Jinyuan’ fruit grown in Danjiangkou and Wuhan orchardsData used for correlation analysis were derived from the near-maturity period of fruit growth, 127–189 DAFB for Danjiangkou fruit (n = 209) and 120–162 DAFB for Wuhan fruit (n = 140).2.4 可溶性总糖和总酸含量变化
对‘金圆’果实中可溶性总糖和总酸(可滴定酸)含量测定的结果表明,可溶性总糖在丹江口和武汉两地果实中的变化趋势高度相似,均呈先低水平稳定不变然后快速增加的趋势,其转折点均为盛花期后127 d(图5:A),此时也是可溶性固形物开始快速增加之时;至盛花期后155 d时,可溶性总糖含量上升至5%附近,到盛花期后189 d时,丹江口果实中可溶性总糖含量增加至9.7%(图5:A)。两地果实中的总酸含量变化趋势也相似,均表现为先快速上升然后稳定在较高水平,在生长前中期(盛花期后100 d内)两地总酸含量逐渐上升,其中武汉果实总酸含量高于丹江口果实,但是到了生长后期两地果实总酸含量较为相似,均维持在1.4%附近(图5:B)。
3. 讨论
3.1 盛花期后57 d内为‘金圆’果实快速生长阶段
对于一个全新的猕猴桃品种而言,研究清楚其果实生长发育规律,对制定果园栽培管理措施,改善果实品质,促进该新品种商业化推广具有重要的指导意义。本研究结果表明,‘金圆’果实纵横侧径生长变化可以分为快速生长-缓慢生长-停滞生长3个阶段,与大多数研究结果一致[8, 10, 13]。丹江口和武汉生产的‘金圆’果实纵横径均有一个生长主峰,即在盛花期后35 d内为果实生长最快阶段,这与‘金艳’、‘贵长’和‘璞玉’果实最快生长阶段发生时间相似[10, 12, 20]。根据果实纵横侧径生长速率的明显变化,将‘金圆’果实快速生长阶段划分在盛花期后57 d内,与‘Hort16A’果实快速生长阶段基本一致[9],但是比‘徐香’、‘金实1号’果实快速生长阶段略长[8, 13]。尽管有少数品种呈现双S甚至3S型生长变化曲线,如‘贵长’和‘红阳’果实的单果重变化[15, 20],然而,在很多研究中单果重的变化曲线很大程度上容易受到人为采样的影响,并不能客观真实反映出果实单果重的变化趋势。因为果实单果重与果实体积高度正相关,通过果实体积来预测单果重的变化成为一种可能[21],这样更能客观真实反映出果实的重量变化规律[22]。本研究中采取类似策略,基于‘金圆’果实体积预测的单果重变化趋势与果实纵横侧径变化趋势一致,也与‘Hort16A’单果重的变化趋势相符[9]。
3.2 ‘金圆’适宜采收期从盛花期后150 ~ 155 d开始
适时采收对于保持果实采后品质和贮藏性能至关重要,果实生长发育规律的解析可为采收期的制定提供科学依据。国内多以猕猴桃果实可溶性固形物含量作为采收参考指标,而忽略了干物质、果肉颜色和果实硬度等指标的重要性。研究表明,猕猴桃采收时的干物质含量决定了果实软熟后的可溶性固形物含量和消费者的喜好程度,并发现‘Hayward’采收时干物质含量 ≥ 16.1%才会被消费者喜爱[23, 24]。本研究中,两地产的‘金圆’果实干物质于盛花期后127 d(武汉)或135 d(丹江口)后进入稳定平台期,经过3周后又小幅上升至16.7%(武汉)或17.7%(丹江口)。因此,‘金圆’果实在合理采收期内具有较高的干物质含量,尤其是丹江口果实,晚采还可以进一步提升干物质含量,以保证更高的果实品质。可溶性固形物和可溶性总糖均是在盛花期后127 d开始快速增加,在此之前主要为淀粉积累,可溶性固形物含量至盛花期后148 d时快速上升至8%,同时可溶性总糖含量也快速增加至3.5%,这可能与淀粉开始水解或和碳水化合物持续运输并积累于果实中有关[25]。对于黄肉猕猴桃品种而言,在成熟过程中果肉颜色由绿色逐渐转变为黄色,其果肉颜色通常要求103 °hue以下时采收以满足消费者对黄色果肉的要求。两地生产的‘金圆’果肉颜色达到103 °hue的时间基本一致,均在盛花期后155 d。本研究中发现‘金圆’果实果肉颜色仅与可溶性固形物紧密相关,而与硬度、干物质等之间无较高的相关性。但是,猕猴桃果肉颜色的转变容易受到环境温度的影响,并不总是与可溶性固形物或硬度紧密相关,例如充分退绿的果实也可能具有较低的可溶性固形物和较高的硬度[22, 25]。因此,果肉颜色、可溶性固形物、硬度以及干物质含量等指标要综合考虑,不能仅仅参考其中的某个指标作为采收依据;在此情况下,‘金圆’果实适宜的采收期应该从盛花期后150 ~ 155 d开始。
3.3 不同产地对‘金圆’果实生长发育有一定影响
猕猴桃果实生长发育存在果园、季节上的差异,说明果实生长发育容易受到果园生长环境的影响。通过2012−2014连续3年对‘金艳’果实生长发育的监测,发现2013年果实单果重明显低于其他两年,推测与2013年谢花后一段时间的干旱有关[10]。本研究分析了丹江口和武汉两个产地对‘金圆’果实生长发育的影响,其生长发育变化趋势在两地之间非常相似,但是武汉产的果实相比较小,生长速率较慢,果实硬度高于丹江口,干物质含量较丹江口果实提前进入稳定平台期,且低于丹江口果实。这可能与武汉产地栽培管理粗放、土壤肥力较低、气候差异较大有关。
3.4 ‘金圆’果实成熟期比母本‘金艳’至少提前3周
‘金圆’与其母本‘金艳’相比,在果实生长发育方面既有相似之处,但也存在一定差异。两者的果实重量、纵横侧径、可溶性固形物、果肉颜色和干物质等指标在生长发育期内具有相似的变化规律,如‘金艳’果实重量和纵横侧径也表现出快速增长-缓慢增长-生长停滞3个不同的生长阶段[10]。然而,两者的果实可溶性固形物和果肉颜色在达到采收标准时所需要的时间上存在差异,‘金艳’果实在谢花后154 ~ 161 d时果肉颜色下降到103 °hue,达到黄肉猕猴桃对果肉颜色的采收要求,而此时的可溶性固形物含量还处在6.0% ~ 7.0%,当谢花后175 d时可溶性固形物才上升到7.5% ~ 8.0%[10]。丹江口和武汉两地生产的‘金圆’果实均在盛花期后148 d时可溶性固形物含量达到8%,在盛花期后175 d时进一步上升到13.8%,但是‘金圆’果肉颜色下降至103 ohue的时间也是发生在盛花期后155 d附近。尽管盛花期和谢花期仅有几天的间隔,但根据本研究结果,发现‘金圆’果实成熟期比‘金艳’至少提前3周。另外,‘金圆’果实采收期时的干物质含量普遍在16.5%之上,晚采时更是高达18.0%,明显高于‘金艳’果实15.0% ~ 16.0%的干物质含量[10],更高的果实干物质含量意味着更好的风味品质。
4. 结论
丹江口和武汉两地生产的‘金圆’猕猴桃果实具有相似的生长发育趋势,但是果实重量、大小、干物质、硬度、总酸等指标存在一定的差距。果实生长变化表现为快速增长-缓慢增长-增长停滞3个阶段,其中盛花期后57 d内为果实快速生长阶段,栽培上需要加强水肥管理,保证果实细胞快速增殖以获得最大产量。综合果实干物质、可溶性固形物、果肉颜色及硬度等指标的变化趋势,‘金圆’果实适宜的采收期应该从盛花期后150 ~ 155 d开始。
-
图 1 水生植物无机碳利用策略的特殊性和多样性
A:中华水韭(Isoetes sinensis Palmer);B:龙舌草(Ottelia alismoides (L.) Pers.)(照片由付文龙拍摄);C:水筛(Blyxa japonica (Miq.) Maxim.);D:穿叶眼子菜(Potamogeton perfoliatus L.);E:一种轮藻(Chara sp.)(照片由刘洋拍摄);F:眼子菜(Potamogeton distinctus A. Bennett);G:紫萍(Spirodela polyrhiza (L.) Schleid)。轮藻不属于植物,但在无机碳利用时,通常将其视为沉水植物。图中pH极性叶片染色显示眼子菜属植物近轴面被酚酞染成红色(碱性),远轴面无色,表明这类叶片在利用HCO3−过程中形成pH极性。溴麝香草酚蓝染色显示轮藻属在利用HCO3−过程中,细胞呈酸性(黄色)和碱性(蓝色)相间(图片来源于Beilby等[57])。
Figure 1. The distinctiveness and diversity of inorganic carbon utilization strategies in aquatic plants
A: Isoetes sinensis Palmer; B: Ottelia alismoides (L.) Pers. (Photographed by Fu Wenlong); C: Blyxa japonica (Miq.) Maxim.; D: Potamogeton perfoliatus L.; E: Chara sp. (Photographed by Liu Yang); F: Potamogeton distinctus A. Bennett; G: Spirodela polyrhiza (L.) Schleid. Characean algae are not plant, but they are usually regarded as submerged plants in study of inorganic carbon utilization. Under phenolphthalein staining, the adaxial surface of Potamogeton plant leaf is red (alkalinity), while the abaxial surface is colorless, indicating pH polarity of two sides of the same leaf during the process of HCO3− use. Under bromothymol blue staining, the interior of Chara cell exhibits alternating acidity (yellow) and alkalinity (blue) during HCO3−use (The image is from Beilby et al. [57]).
表 1 植物在水生环境中面临的机遇和挑战及水生植物的应对方式(改自Maberly 和 Gontero[14])
Table 1 Opportunities and challenges faced by plants in aquatic environments and how aquatic plants respond (modified from Maberly and Gontero[14])
环境特征
Environmental feature机遇
Opportunity挑战
Challenge水生植物应对方式
Aquatic plant response水分可利用性高 无水分胁迫 藻类竞争 生产力高;表皮细胞包含叶绿体;
叶片薄;分泌化感物质生长介质密度高 支撑性高 水阻力大 机械组织投资减少;茎和叶具有韧性 光照可利用性低 光抑制和光伤害可能低 光合作用和分布深度受限 表皮细胞富含叶绿体 温度变化幅度小 温度胁迫风险小 无 无 O2可利用性低 光呼吸可能低 地下组织器官缺氧 通气组织贯通根茎叶;向地下部位泵氧 无机碳可利用性低 局部生境CO2多;
HCO3−浓度高CO2日变化和年变化
范围极大拓展到局部高CO2生境生长;发展无机碳浓缩机制:HCO3−利用、C4和景天酸代谢(CAM) 养分可利用性高 根、茎、叶均可接触营养元素 藻类竞争 根茎叶均吸收养分;化感作用 表 2 水鳖科植物无机碳利用策略的多样性
Table 2 Diversity of inorganic carbon utilization strategies in Hydrocharitaceae plants
属
Genus种数
No. of speciesHCO3−利用
Bicarbonate use大气CO2
Atmosphere CO2基质CO2
Substrate CO2C4途径
C4 pathwayCAM途径
CAM pathwayAppertiella 1 U U U U U Blyxa[50, 56] 14 N N S N N Elodea[50, 75] 9 Y N U I/N N Enhalus[76] 1 Y N U U U Halophila[77] 17 Y N U N N Hydrilla[78, 73] 1 Y N U I S Hydrocharisa 5 N Y U U U Lagarosiphon[50] 9 Y/N U U U U Najas[50] 39 Y/N N U N N Nechamandra[56, 79] 1 Y N U U S Ottelia[45, 79-81] 23 Y Y U Y/N I/N Stratiotes[82] 1 Y Y U U U Thalassia[77,83,84] 2 Y N U S N Vallisneria[56, 84] 14 Y N Y N S/N 注:Y,具备该途径;N,不具备该途径;S,疑似具备该途径;U,尚未进行测试;I,需要在特殊条件下诱导出该途径;Y/N,在已测试的该属所有物种中,有的物种具有该途径,有的物种不具有该途径;I/N,在已测试的该属所有物种中,有的物种该途径的产生需要诱导,有的物种则不具备该途径;S/N,在已测试的该属所有物种中,有些物种疑似具有该途径,有的物种不具备该途径。a,数据来源于本实验室。 Notes: Y, all plants have this pathway; N, none plant have this pathway; S, the plants are suspected to have this pathway; U, not yet tested; I, this pathway needs to be induced under special conditions; Y/S, among all the tested species from this genus, some have this pathway and some do not; I/N, among all the tested species from this genus, some need to be induced to produce this pathway and some do not have this pathway; S/N, among all the tested species from this genus, some are suspected to have this pathway and some do not have. a, indicates the data are from our lab. -
[1] Les DH,Philbrick CT. Studies of hybridization and chromosome number variation in aquatic angiosperms:evolutionary implications[J]. Aquat Bot,1993,44 (2-3):181−228. doi: 10.1016/0304-3770(93)90071-4
[2] Den Hartog C, Kuo J. Taxonomy and biogeography of seagrasses[M]//Larkum AWD, Orth RJ, Duarte CM, eds. Seagrasse: Biology, Ecology and Conservation. Berlin Heidelberg: Springer, 2006: 1-23.
[3] Cook CD. Aquatic Plant Book[M]. The Hague: SPB Academic Publishing, 1990: 1-7
[4] Les DH,Cleland MA,Waycott M. Phylogenetic studies in Alismatidae,Ⅱ:evolution of marine angiosperms (seagrasses) and hydrophily[J]. Syst Bot,1997,22 (3):443−463. doi: 10.2307/2419820
[5] Friis EM,Pedersen KR,Crane PR. Fossil evidence of water lilies (Nymphaeales) in the Early Cretaceous[J]. Nature,2001,410 (6826):357−360. doi: 10.1038/35066557
[6] Gomez B,Daviero-Gomez V,Coiffard C,Martín-Closas C,Dilcher DL. Montsechia,an ancient aquatic angiosperm[J]. Proc Natl Acad Sci USA,2015,112 (35):10985−10988. doi: 10.1073/pnas.1509241112
[7] Les DH. Water from the rock:ancient aquatic angiosperms flow from the fossil record[J]. Proc Natl Acad Sci USA,2015,112 (35):10825−10826. doi: 10.1073/pnas.1514280112
[8] Philbrick CT,Les DH. Evolution of aquatic angiosperm reproductive systems[J]. BioScience,1996,46 (11):813−826. doi: 10.2307/1312967
[9] Les DH, Tippery NP. In time and with water … the systematics of alismatid monocotyledons[M]//Wilkin P, Mayo SJ, eds. Early Events in Monocot Evolution. Cambridge: Cambridge University Press, 2013: 1-100.
[10] Maberly SC,Spence DHN. Photosynthesis and photorespiration in freshwater organisms:amphibious plants[J]. Aquat Bot,1989,34 (1-3):267−286. doi: 10.1016/0304-3770(89)90059-4
[11] Santamaría L. Why are most aquatic plants widely distributed? Dispersal,clonal growth and small-scale heterogeneity in a stressful environment[J]. Acta Oecol,2002,23 (3):137−154. doi: 10.1016/S1146-609X(02)01146-3
[12] Li W. Environmental opportunities and constraints in the reproduction and dispersal of aquatic plants[J]. Aquat Bot,2014,118:62−70. doi: 10.1016/j.aquabot.2014.07.008
[13] Maberly SC. The fitness of the environments of air and water for photosynthesis,growth,reproduction and dispersal of photoautotrophs:an evolutionary and biogeochemical perspective[J]. Aquat Bot,2014,118:4−13. doi: 10.1016/j.aquabot.2014.06.014
[14] Maberly SC, Gontero B. Trade-offs and synergies in the structural and functional characteristics of leaves photosynthesizing in aquatic environments[M]//Adams Ⅲ WW, Terashima I, eds. The Leaf: A platform for Performing Photosynthesis. Chambrige: Springer, 2018: 307-343.
[15] 沈允钢, 施教耐, 许大全. 动态光合作用[M]. 北京: 科学出版社, 1998: 1-6. [16] Niklaus M,Kelly S. The molecular evolution of C4 photosynthesis:opportunities for understanding and improving the world's most productive plants[J]. J Exp Bot,2019,70 (3):795−804. doi: 10.1093/jxb/ery416
[17] Raven JA,Cockell CS,de La Rocha CL. The evolution of inorganic carbon concentrating mechanisms in photosynthesis[J]. Philos Trans Roy Soc B:Biol Sci,2008,363 (1504):2641−2650. doi: 10.1098/rstb.2008.0020
[18] Sage RF. A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery:species number,evolutionary lineages,and Hall of Fame[J]. J Exp Bot,2016,67 (14):4039−4056. doi: 10.1093/jxb/erw156
[19] Silvera K,Neubig KM,Whitten WM,Williams NH,Winter K,Cushman JC. Evolution along the crassulacean acid metabolism continuum[J]. Funct Plant Biol,2010,37 (11):995−1010. doi: 10.1071/FP10084
[20] Sage RF. Are crassulacean acid metabolism and C4 photosynthesis incompatible?[J]. Funct Plant Biol,2002,29 (6):775−785. doi: 10.1071/PP01217
[21] Winter K, Smith JAC. Crassulacean Acid Metabolism: Biochemistry, Ecophysiology and Evolution[M]. Berlin Heidelberg: Springer, 1996: 19-420.
[22] Sage RF, Monson RK. C4 Plant Biology[M]. San Diego: Academic Press, 1998: 10-375.
[23] Keeley JE,Rundel PW. Evolution of CAM and C4 carbon-concentrating mechanisms[J]. Int J Plant Sci,2003,164 (S3):S55−S77. doi: 10.1086/374192
[24] Griffiths H. Carbon dioxide concentrating mechanisms and the evolution of CAM in vascular epiphytes[M]//Lüttge U, ed. Vascular Plants as Epiphytes: Evolution and Ecophysiology. Berlin Heidelberg: Springer, 1989: 42-86.
[25] Sage RF. Environmental and evolutionary preconditions for the origin and diversification of the C4 photosynthetic syndrome[J]. Plant Biol,2001,3 (3):202−213. doi: 10.1055/s-2001-15206
[26] Hatch MD,Slack CR. Photosynthesis by sugar-cane leaves. A new carboxylation reaction and the pathway of sugar formation[J]. Biochem J,1966,101 (1):103−111. doi: 10.1042/bj1010103
[27] Raghavendra AS, Sage RF. C4 Photosynthesis and Related CO2 Concentrating Mechanisms[M]. Media: Springer, 2011: 161-195.
[28] Cushman JC,Bohnert HJ. CRASSULACEAN ACID METABOLISM:molecular genetics[J]. Annu Rev Plant Physiol Plant Mol Biol,1999,50:305−332. doi: 10.1146/annurev.arplant.50.1.305
[29] Raven JA. Nutrient transport in microalgae[J]. Adv Microb Physiol,1981,21:47−226.
[30] Raven JA,Giordano M,Beardall J. Insights into the evolution of CCMs from comparisons with other resource acquisition and assimilation processes[J]. Physiol Plant,2008,133 (1):4−14. doi: 10.1111/j.1399-3054.2007.01024.x
[31] Sage RF. The evolution of C4 photosynthesis[J]. New Phytol,2004,161 (2):341−370. doi: 10.1111/j.1469-8137.2004.00974.x
[32] Black CC Jr. Photosynthetic carbon fixation in relation to net CO2 uptake[J]. Ann Rev Plant Physiol,1973,24:253−286. doi: 10.1146/annurev.pp.24.060173.001345
[33] Han HE,Felker P. Field validation of water-use efficiency of the CAM plant Opuntia ellisianain south Texas[J]. J Arid Environ,1997,36 (1):133−148. doi: 10.1006/jare.1996.0202
[34] Pearson PN,Palmer MR. Atmospheric carbon dioxide concentrations over the past 60 million years[J]. Nature,2000,406 (6797):695−699. doi: 10.1038/35021000
[35] Maberly SC,Gontero B. Ecological imperatives for aquatic CO2 concentrating mechanisms[J]. J Exp Bot,2017,68 (14):3797−3814. doi: 10.1093/jxb/erx201
[36] Raven JA. Exogenous inorganic carbon sources in plant photosynthesis[J]. Biol Rev,1970,45 (2):167−220. doi: 10.1111/j.1469-185X.1970.tb01629.x
[37] Raven JA,Beardall J. CO2 concentrating mechanisms and environmental change[J]. Aquat Bot,2014,118:24−37. doi: 10.1016/j.aquabot.2014.05.008
[38] Maberly SC,Spence DHN. Photosynthetic inorganic carbon use by freshwater plants[J]. J Ecol,1983,71 (3):705−724. doi: 10.2307/2259587
[39] Cole JJ,Caraco NF,Kling GW,Kratz TK. Carbon dioxide supersaturation in the surface waters of lakes[J]. Science,1994,265 (5178):1568−1570. doi: 10.1126/science.265.5178.1568
[40] Madsen TV,Sand-Jensen K. Photosynthetic carbon assimilation in aquatic macrophytes[J]. Aquat Bot,1991,41 (1-3):5−40. doi: 10.1016/0304-3770(91)90037-6
[41] Maberly SC,Madsen TV. Affinity for CO2 in relation to the ability of freshwater macrophytes to use HCO3−[J]. Funct Ecol,1998,12 (1):99−106. doi: 10.1046/j.1365-2435.1998.00172.x
[42] Maberly SC,Madsen TV. Freshwater angiosperm carbon concentrating mechanisms:processes and patterns[J]. Funct Plant Biol,2002,29 (3):393−405. doi: 10.1071/PP01187
[43] Klavsen SK,Maberly SC. Effect of light and CO2 on inorganic carbon uptake in the invasive aquatic CAM-plant Crassula helmsii[J]. Funct Plant Biol,2010,37 (8):737−747. doi: 10.1071/FP09281
[44] Klavsen SK,Madsen TV,Maberly SC. Crassulacean acid metabolism in the context of other carbon-concentrating mechanisms in freshwater plants:a review[J]. Photosynth Res,2011,109 (1-3):269−279. doi: 10.1007/s11120-011-9630-8
[45] Zhang YZ,Yin LY,Jiang HS,Li W,Gontero B,Maberly SC. Biochemical and biophysical CO2 concentrating mechanisms in two species of freshwater macrophyte within the genus Ottelia (Hydrocharitaceae)[J]. Photosynth Res,2014,121 (2-3):285−297. doi: 10.1007/s11120-013-9950-y
[46] Maberly SC,Stott AW,Gontero B. The differential ability of two species of seagrass to use carbon dioxide and bicarbonate and their modelled response to rising concentrations of inorganic carbon[J]. Front Plant Sci,2022,13:936716. doi: 10.3389/fpls.2022.936716
[47] Wickell D,Kuo LY,Yang HP,Ashok AD,Irisarri I,et al. Underwater CAM photosynthesis elucidated by Isoetes genome
[J]. Nat Commun,2021,12 (1):6348. doi: 10.1038/s41467-021-26644-7 [48] Huang WM,Han SJ,Jiang HS,Gu SP,Li W,et al. External α-carbonic anhydrase and solute carrier 4 are required for bicarbonate uptake in a freshwater angiosperm[J]. J Exp Bot,2020,71 (19):6004−6014. doi: 10.1093/jxb/eraa351
[49] Magnin NC,Cooley BA,Reiskind JB,Bowes G. Regulation and localization of key enzymes during the induction of Kranz-less,C4-type photosynthesis in Hydrilla verticillata[J]. Plant Physiol,1997,115 (4):1681−1689. doi: 10.1104/pp.115.4.1681
[50] Iversen LL,Winkel A,Baastrup-Spohr L,Hinke AB,Alahuhta J,et al. Catchment properties and the photosynthetic trait composition of freshwater plant communities[J]. Science,2019,366 (6467):878−881. doi: 10.1126/science.aay5945
[51] Maberly SC. Photosynthesis by Fontinalis antipyretica[J]. New Phytol,1985,100 (2):127−140. doi: 10.1111/j.1469-8137.1985.tb02765.x
[52] Maberly SC. Photosynthesis by Fontinalis antipyretica. Ⅱ. Assessment of environmental factors limiting photosynthesis and production[J]. New Phytol,1985,100 (2):141−155. doi: 10.1111/j.1469-8137.1985.tb02766.x
[53] Pedersen O,Pulido C,Rich SM,Colmer TD. In situ O2 dynamics in submerged Isoetes australis:varied leaf gas permeability influences underwater photosynthesis and internal O2[J]. J Exp Bot,2011,62 (13):4691−4700. doi: 10.1093/jxb/err193
[54] Casati P,Lara MV,Andreo CS. Induction of a C4-like mechanism of CO2 fixation in Egeria densa,a submersed aquatic species[J]. Plant Physiol,2000,123 (4):1611−1622. doi: 10.1104/pp.123.4.1611
[55] Keeley JE. Isoetes howellii:a submerged aquatic CAM plant?[J]. Am J Bot,1981,68 (3):420−424. doi: 10.1002/j.1537-2197.1981.tb06380.x
[56] Yin LY,Li W,Madsen TV,Maberly SC,Bowes G. Photosynthetic inorganic carbon acquisition in 30 freshwater macrophytes[J]. Aquat Bot,2017,140:48−54. doi: 10.1016/j.aquabot.2016.05.002
[57] Beilby MJ,Bisson MA,Schneider SC. How Characean algae take up needed and excrete unwanted ions: an overview explaining how insights from electrophysiology are useful to understand the ecology of aquatic macrophytes[J]. Aquat Bot,2022,181:103542. doi: 10.1016/j.aquabot.2022.103542
[58] Wang Q. Hydrocharitaceae[M]//Flora of China. Beijing and St. Louis: Science Press and Missouri Botanical Garden Press, 2010: 91-102.
[59] Chen LY,Chen JM,Gituru RW,Wang QF. Generic phylogeny,historical biogeography and character evolution of the cosmopolitan aquatic plant family Hydrocharitaceae[J]. BMC Evol Biol,2012,12:30. doi: 10.1186/1471-2148-12-30
[60] Chen LY,Chen JM,Gituru RW,Wang QF. Eurasian origin of Alismatidae inferred from statistical dispersal-vicariance analysis[J]. Mol Phylogenet Evol,2013,67 (1):38−42. doi: 10.1016/j.ympev.2013.01.001
[61] Olsen JL,Rouzé P,Verhelst B,Lin YC,Bayer T,et al. The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea[J]. Nature,2016,530 (7590):331−335. doi: 10.1038/nature16548
[62] Cook CDK,Urmi-König K. A revision of the genus Egeria (Hydrocharitaceae)[J]. Aquat Bot,1984,19 (1-2):73−96. doi: 10.1016/0304-3770(84)90009-3
[63] Li ZZ,Wu S,Zhou CY,Liu Y,Hu GW,et al. Ottelia fengshanensis,a new bisexual species of Ottelia (Hydrocharitaceae) from southwestern China[J]. PhytoKeys,2019,135:1−10. doi: 10.3897/phytokeys.135.38531
[64] Li ZZ,Liao K,Zou CY,Liu Y,Hu GW,et al. Ottelia guanyangensis (Hydrocharitaceae),a new species from southwestern China[J]. Phytotaxa,2018,361 (3):294−300. doi: 10.11646/phytotaxa.361.3.5
[65] Misra MP. Cytological studies in Ottelia alismoides pers[J]. Cytologia,1974,39 (3):419−427. doi: 10.1508/cytologia.39.419
[66] Krishnappa DG. Cytological studies in some aquatic angiosperms[J]. Proc/Indian Acad Sci,1971,73 (4):179−185.
[67] Chaudhuri JB,Sharma A. Cytological studies on three aquatic members of hydrocharitaceae in relation to their morphological and ecological characteristics[J]. Cytologia,1978,43 (1):1−19. doi: 10.1508/cytologia.43.1
[68] Salvucci ME,Bowes G. Induction of reduced photorespiratory activity in submersed and amphibious aquatic macrophytes[J]. Plant Physiol,1981,67 (2):335−340. doi: 10.1104/pp.67.2.335
[69] Salvucci ME,Bowes G. Ethoxyzolamide repression of the low photorespiration state in two submersed angiosperms[J]. Planta,1983,158 (1):27−34. doi: 10.1007/BF00395399
[70] Shao H,Gontero B,Maberly SC,Jiang HS,Cao Y,et al. Responses of Ottelia alismoides,an aquatic plant with three CCMs,to variable CO2 and light[J]. J Exp Bot,2017,68 (14):3985−3995. doi: 10.1093/jxb/erx064
[71] Pedersen O. Jack of all trades-C4 photosynthesis,CAM and HCO3− use in the same tissue. A commentary on:'Structural basis for C4 photosynthesis without Kranz anatomy in leaves of the submerged freshwater plant Ottelia alismoides'[J]. Ann Bot,2020,125 (6):iv−vi. doi: 10.1093/aob/mcaa034
[72] Han SJ,Maberly SC,Gontero B,Xing ZF,Li W,et al. Structural basis for C4 photosynthesis without Kranz anatomy in leaves of the submerged freshwater plant Ottelia alismoides[J]. Ann Bot,2020,125 (6):869−879. doi: 10.1093/aob/mcaa005
[73] Reiskind JB,Madsen TV,Van Ginkel LC,Bowes G. Evidence that inducible C4-type photosynthesis is a chloroplastic CO2-concentrating mechanism in Hydrilla,a submersed monocot[J]. Plant Cell Environ,1997,20 (2):211−220. doi: 10.1046/j.1365-3040.1997.d01-68.x
[74] Rao SK,Magnin NC,Reiskind JB,Bowes G. Photosynthetic and other phosphoenolpyruvate carboxylase isoforms in the single-cell,facultative C4 system of Hydrilla verticillata[J]. Plant Physiol,2002,130 (2):876−886. doi: 10.1104/pp.008045
[75] Lara MV,Casati P,Andreo CS. CO2-concentrating mechanisms in Egeria densa,a submersed aquatic plant[J]. Physiol Plant,2002,115 (4):487−495. doi: 10.1034/j.1399-3054.2002.1150402.x
[76] Luan WY,Li H,Zhang LT,Liu JG. Enhalus acoroides efficiently alleviate ocean acidification by shifting modes of inorganic carbon uptake and increasing photosynthesis when pH drops[J]. Mar Environ Res,2023,186:105896. doi: 10.1016/j.marenvres.2023.105896
[77] Gavin NM,Durako MJ. Carbon acquisition mechanisms in Halophila johnsonii and Thalassia testudinum[J]. Aquat Bot,2019,152:64−69. doi: 10.1016/j.aquabot.2018.11.001
[78] Holaday AS,Bowes G. C4 acid metabolism and dark CO2 fixation in a submersed aquatic macrophyte (Hydrilla verticillata)[J]. Plant Physiol,1980,65 (2):331−335. doi: 10.1104/pp.65.2.331
[79] Wang SN,Li PP,Liao ZY,Wang WW,Chen T,et al. Adaptation of inorganic carbon utilization strategies in submerged and floating leaves of heteroblastic plant Ottelia cordata[J]. Environ Exp Bot,2022,196:104818. doi: 10.1016/j.envexpbot.2022.104818
[80] Cao Y,Liu Y,Ndirangu L,Li W,Xian L,Jiang HS. The analysis of leaf traits of eight Ottelia populations and their potential ecosystem functions in karst freshwaters in China[J]. Front Plant Sci,2019,9:1938. doi: 10.3389/fpls.2018.01938
[81] Liao ZY,Li PP,Zhou JZ,Li W,Jiang HS. Different photosynthetic inorganic carbon utilization strategies in the heteroblastic leaves of an aquatic plant Ottelia ovalifolia[J]. Front Plant Sci,2023,14:1142848. doi: 10.3389/fpls.2023.1142848
[82] Prins HBA,de Guia MB. Carbon source of the water soldier,Stratiotes aloides L.[J]. Aquat Bot,1986,26:225−234. doi: 10.1016/0304-3770(86)90023-9
[83] Beer S,Waisel Y. Some photosynthetic carbon fixation properties of seagrasses[J]. Aquat Bot,1979,7:129−138. doi: 10.1016/0304-3770(79)90017-2
[84] Benedict CR,Scott JR. Photosynthetic carbon metabolism of a marine grass[J]. Plant Physiol,1976,57 (6):876−880. doi: 10.1104/pp.57.6.876
[85] Von Caemmerer S,Quick WP,Furbank RT. The development of C4 rice:current progress and future challenges[J]. Science,2012,336 (6089):1671−1672. doi: 10.1126/science.1220177
-
期刊类型引用(1)
1. 赵素婷,周瑞,袁赛波,厉恩华. 长江中下游浅水湖泊湿地植物保护与恢复. 人民长江. 2025(01): 58-66 . 百度学术
其他类型引用(2)