山黧豆毒素ODAP的生物合成及与抗逆性关系研究进展

有关山黧豆毒素ODAP的生物合成途径的前体物和合成程序已经证实,但其关键合成酶尚未分离与鉴定,因而无法克隆相应基因和利用反义RNA技术以控制其生物合成。研究表明,利用相应的抑制剂控制ODAP生物合成前体物可降低ODAP的积累量。山黧豆中ODAP含量与其抗逆性之间密切相关,这与其能有效地清除山黧豆中·OH自由基有关,外源ODAP处理获同样效果。此外,因ODAP既是含氮化合物,又是游离氨基酸,极易溶于水,可在逆境胁迫下与脯氨酸和多胺一样大量而迅速地积累,推测它也可能作为细胞渗透调节物质和防脱水剂,并在氮代谢和能量代谢方面起重要作用。对今后该领域的重点研究方向也进行了探讨。     

安徽山黧豆的核型

山黧豆属(又名香豌豆属)(Lathyrus Linn.)全世界共约140种,已做过染色体计数者72种。我国约16种,大部分产西南、西北和东北各省区。近年来皖南农学院朱玉简等同志在安徽宣城发现一新种,命名为安徽山黧豆(Lathyrus anhuiensis Y.J.Zhu et R.X.Meng)。鉴于该新种分布区非常局限,个体数也不多,为了及时掌握其细胞学情况,特通过该院叶如欣同志取得部分种子进行了染色体的计数和核型的描述。     

山黧豆及其神经毒素(ODAP)的研究进展

山黧豆具有耐寒、耐旱等优良生产性状,且营养丰富,在恶劣的天气条件下仍能维持较高的产量,因此它是半干旱地区的潜在粮食作物。但长期食用山黧豆会引起中毒,这是由于山黧豆中含有的神经毒素（ＯＤＡＰ）所致,因此筛选无毒品系具有重要意义。本文对山黧豆神经毒素（ＯＤＡＰ）的生物合成毒素异构化等方面作简要综述。     

山黧豆毒素的薄层分离

通过对山黧豆中常见的20几种游离氨基酸薄层层析发现,其毒素ODAP的Rf值与好几种相关氨基酸的接近,而用阳离子交换柱对氨基酸抽提样进行简单的分离纯化,第一个洗脱出来的即为ODAP,这样在排除其它氨基酸干扰的情况下再进行ODAP的薄层分析将得到准确的结果。     

山黧豆属作物在土耳其的栽培与利用状况

众所周知,山黧豆起源于巴尔干半岛并传播到世界各地。在土耳其,山黧豆属作物有73个分类群(约1/3为地方特有种),在全国各地均有分布种植,但主要集中在黑海中部、东南部和安纳托利亚东部地区。该文介绍了山黧豆属作物在土耳其全国的分布和在局部地区的食用、观赏等资源利用和保存情况。通常,不同国家人民会因为文化差异形成不同的饮食习惯,但山黧豆大多被用于制作汤、面包或其他咸点。山黧豆的栽培技术则因地制宜,土耳其在边缘土地上进行旱作种植,中国和印度部分地区多采用轮作种植方法等。作为一种极“小众”的作物,山黧豆研究工作的从业人员极少,而且缺乏大型联合研究项目。因此,需要联合化学、表型和分子分析等方法,以保护世界各地包括土耳其在内的地方种质资源,尤其是培育适合土耳其、中国等世界各国的食饲兼用型低β-ODAP品种。总之,选育低β-ODAP或不含β-ODAP的山黧豆品种将有助于丰富人类在食用、饲用和观赏等方面的物种资源利用。     

渗透胁迫对山黧豆幼苗H2O2及毒素积累的影响

用PEG经根部处理15d龄的山黧豆幼苗,取幼苗叶片为实验材料,测定过氧化氢酶（CAT）、过氧化物酶（POD）活性、过氧化氢（H2O2）和毒素（β-N-oxalyl-α,β-diaminopropionic acid,ODAP）的含量。结果表明,随着PEG处理时间的延长,POD和CAT活性降低,而H2O2和ODAP含量显著升高;在PEG处理液中加入二乙基二硫代氨基甲酸钠(diethyldithiocarbamate,DDC)和氨基三唑(aminotriazole,AT)后分别抑制和促进H2O2的产生,DDC可降低叶片中ODAP的含量,AT则使ODAP积累。由此我们推测,水分胁迫条件下活性氧代谢与ODAP的积累有关。     

山黧豆胚胎发育过程中ODAP和一些大分子物质含量的变化

应用微量分析方法检测了山黧豆胚胎发育过程中ODAP毒素含量和核酸、蛋白质、糖类等大分子物质的含量变化。结果表明:每粒种子的ODAP含量随着胚的发育而增加。每粒种子DNA量随着细胞的迅速分裂而增加,R、蛋白质、淀粉含量随着胚的发育而成倍地增加,当进入心形胚时这些物质的增加更为迅速。如以每克干重中的含量来表示,那么ODAP、DNA及可溶性糖含量则随胚的发育而下降,其它大分子物质含量在胚发育前期升高,进入心形胚时,这些物质达到最高峰;到鱼雷胚时,这些物质含量开始下降,直到胚基本分化完全时,降到最低点;只有酸性蛋白质含量一直保持增长。     

交替灌溉对山黧豆叶片气体交换和土壤水分以及产量指标的影响

改变土壤根系的分布以汲取深层土壤水分的能力是植物避免干旱的主要策略。山黧豆是一种抗逆性强的豆类作物,该研究通过起垄条播控制性沟灌的方式,设置传统灌溉(FI)、交替灌溉(PRD,灌水量减少50%)和不灌溉(NI)3种处理模式,探索不同灌溉模式对播种后不同时期山黧豆土壤水分、根系分布、叶片气体交换、水分利用效率和籽粒产量的影响。结果表明：(1)在FI、PRD和NI处理下,山黧豆的根系分别有89.8%、86.9%和84.9%生长在0~20 cm的表层土壤中;干旱胁迫使PRD和NI处理下深层土壤中根系的比例提高至13.05%和15.07%。(2)在整个生育期内,土壤干旱显著降低了山黧豆叶片的净光合速率、蒸腾速率和气孔导度;在种植后60 d时,PRD和NI处理下叶片的瞬时水分利用效率分别较FI处理显著提高了21.4%和14.9%。(3)干旱胁迫显著降低了山黧豆植株高度、第一豆荚高、平均结荚数和豆粒数以及地上部和根系的干重,但显著增加了根冠比;PRD处理对豆荚长度、豆荚重和每荚豆粒重没有显著影响;PRD和NI处理下山黧豆平均籽粒产量分别比FI处理显著降低了53%和63%。研究发现,在干旱胁迫条件下,山黧豆能够通过提高深层土壤中根系的比例、更多吸收深层土壤水分、显著增加根冠比以及显著提高生殖生长期叶片的瞬时水分利用效率,减轻干旱胁迫对自身生长的影响。该研究结果可为山黧豆在旱区推广种植提供理论依据。     

山黧豆根系对H2O2诱导氧化胁迫的生理应答

以水培7d苗龄的山黧豆幼苗为材料,向水培溶液中施加不同浓度H2O2处理山黧豆幼苗24h,分析山黧豆根系受氧化胁迫的程度与抗氧化系统的应答特征,以揭示山黧豆对氧化胁迫的耐受机制。结果显示:(1)随外源H2O2处理浓度的不断增加,山黧豆幼苗侧根的数目无显著变化,而其根的鲜重则显著降低。(2)同时,根系组织的内源H2O2染色范围和程度显著增高,但根尖区域始终保持较低水平的H2O2;相反,O-·2染色范围和程度明显减少,根尖区域却始终保持较高水平的O-·2。(3)同期根系抗坏血酸(ASC)含量及过氧化氢酶(CAT)、过氧化物酶(POD)与抗坏血酸过氧化物酶(APX)的活性均表现出了先升高后降低的趋势,而超氧化物歧化酶(SOD)一直表现为持续上升的趋势。研究表明,在外源H2O2胁迫条件下,山黧豆根系O-·2的积累可能与其生长和活力呈正相关,而根系H2O2的积累则与其受氧化胁迫程度呈正相关;低浓度的H2O2处理可以提高山黧豆抗氧化系统对体内活性氧的清除能力。     

盐分和干旱对沙枣幼苗生理特性的影响

以沙枣(Elaeagnus angustifolia L.)幼苗为实验材料,分别对其进行轻度干旱(土壤含水量7%—9%)、重度干旱(土壤含水量3%—5%)、100 mmol/L NaCl以及100 mmol/L NaCl处理下不同程度的盐旱共胁迫处理,处理2周后测其生理指标,包括生长指标、光合指标、渗透调节指标以及复水后生长指标,研究盐旱共胁迫对沙枣幼苗生理特性的影响。结果表明:和对照相比,轻度干旱对沙枣幼苗的生物量没有显著影响,重度干旱处理明显降低了沙枣的生物量,无论是轻度干旱还是重度干旱,都显著降低了沙枣幼苗的净光合速率、K~+含量,显著增加了Na~+含量、脯氨酸含量、可溶性糖含量、有机酸含量、总酚和类黄酮含量;和对照相比,100 mmol/L NaCl处理显著降低了沙枣幼苗的生物量、净光合速率和K~+含量,显著增加了Na~+含量、脯氨酸含量、可溶性糖含量、有机酸含量、总酚和类黄酮含量;和盐处理相比,轻度干旱和盐分共胁迫对沙枣幼苗的各项指标没有显著差异,而重度干旱和盐分共胁迫明显降低了沙枣幼苗的生物量、净光合速率;复水一周后,只有轻度干旱可以回复到对照水平。以上结果表明,盐分和干旱处理明显抑制了沙枣幼苗的生长,轻度干旱和盐分共胁迫条件下,沙枣幼苗表现出一定的交叉适应现象,而重度干旱却加重了盐害。     

Effects of europium ions (Eu3+) on the distribution and related biological activities of elements in Lathyrus sativus L. roots

Scanning electron microscopic and energy-dispersive X-ray analyses were used to study the distributions of different types of elements in the epidermis, exodermis, endodermis, and vascular cylinder of the fracture face in the Lathyrus sativus L. roots in the presence or absence of Eu³⁺. Some index of the biological activity related to the elements binding with protein were determined also. The results showed that the tissular distributions of elements in the fracture face are different in the presence and absence of Eu³⁺. The atomic percentages of P, S, Ca, and Mn were influenced more than those of other elements. Eu³⁺ promoted the biological activities of various kinds of element. The one possible mechanism changing the biological activities was that the reaction of Eu³⁺ Eu²⁺ would influence the electron capture or transport in elements of binding protein. Another mechanism was that CaM-Ca²⁺ becoming CaM-Eu³⁺ through Eu³⁺ instead of Ca²⁺ would affect the biological activity of elements by regulating the Ca²⁺ level in the plant cell.     

High-frequency plant regeneration by <Emphasis Type="Italic">in vitro</Emphasis> shoot proliferation in cotyledonary node explants of grasspea (<Emphasis Type="Italic">Lathyrus sativus</Emphasis> L.)

Summary Multiple shoots were induced from cotyledonary nodes of grasspea (Lathyrus sativus L.) derived from 7-d-old in vitro seedlings on Murashige and Skoog (MS) medium containing N⁶-benzyladenine (BA), kinetin, or thidiazuron, BA being the most effective. Among the five genotypes tested, shoot proliferation frequency was the highest (93.3%) for IC-120487, giving the maximum number of shoots (11.3 shoots per explant) on MS medium augmented with 2.0 mgl⁻¹ (8.87 μM) BA. Shoot cultures were established by repeatedly subculturing the original cotyledonary nodes on fresh medium after each harvest of the newly formed shoots. Thus 30–40 shoots were obtained in 2 mo. from a single cotyledonary node. Up to 81.8% of the shoots developed roots following transfer to half-strength MS medium containing 0.5 mgl⁻¹ (2.85 μM) indole-3-acetic acid. Plantlets were successfully acclimatized and established in soil.     

History and traditional cultivation ofLathyrus sativus L. andLathyrus citera L. in the Iberian peninsula

Recent ethnographic research carried out in Spain has allowed the cultivation ofLathyrus sativus L. andL. cicera L. to be documented. Both species already appear in the Spanish archaeological record. Grown under traditional farming systems,L. sativus L. andL. cicera L. are still used for human consumption (onlyL. sativus L.) and both are used for fodder. Data on cultivation history, fanning practices, crop processing sequence and uses are here presented, which will enable a better understanding of their possible roles in prehistoric times.     

山黧豆幼苗对干旱胁迫的生理响应

用PEG6000模拟干旱对山黧豆进行胁迫。结果发现,胁迫初期（0~48 h）,突然的水分亏缺使气孔导度（Sc）和蒸腾速率（Tr）迅速下降,而净光合速率（Pn）和水分有效利用率（WUE）基本维持稳定。胁迫后期（48~108 h）,上述四个光合指标均不同程度地向对照水平恢复;脯氨酸和相对电导率（REC）受胁迫强度影响较小,但与胁迫时间呈明显正相关,分别在48和60 h增幅最大,而且当REC上升至对照的50%左右时,脯氨酸含量已达对照的14倍之多。由此认为,山黧豆可能主要通过迅速减小Sc和Tr以及大量而急剧的积累脯氨酸来减轻干旱所造成的伤害。     

Effect of soil mechanical impedance on root growth of two rice varieties under field drought stress

Two upland rice varieties, Azucena and Bala, were screened for root growth under droughted and irrigated treatments in two field sites at the West Africa Rice Development Association (WARDA) experimental farm, Côte d’Ivoire, during the dry season of 1999/2000. The sites were chosen to represent contrasting soil profile penetration resistance (PR) characteristics on upland sites, although both were relatively impeding. The number of nodal root axes per unit area passing through horizontal transects (root density) was counted at 35, 56, 77 and 98 days after sowing (DAS) at 10 cm depth intervals. Azucena consistently maintained a greater root density than Bala and a greater proportion of Azucena roots grew to 30 cm depth (22.7% vs. 8.4% at 77 DAS). There was little detectable effect of water regime on root distribution but evidence of lower root numbers at depths below 20 cm in the higher PR site was revealed. A site by variety by soil depth interaction suggests that Azucena roots are more strongly affected by very high PR than those of Bala. PR between 0–30 cm depth increased greatly with decreasing soil water content during the drought as the soil dried. This increase is likely to have prevented or greatly impaired further nodal root growth within this layer. At 40 cm depth, PR was high (3–4 MPa) but did not increase during the drought. At this depth root growth rate was likely to be greatly reduced despite the availability of water. These results demonstrate that varietal differences in root morphology characterised in the laboratory can be also detected in impeding field soils as differences in the density of roots at depth. Relatively poor root growth in these fields in the absence of drought was probably due to the high mechanical impedance and/or the physiological stress of the plants in the dry season. Our results indicate that high mechanical impedance was a more fundamental constraint on root growth than soil water availability during the drought. Thus, varietal differences in root penetration ability might be very important for drought avoidance in soils of this type.     

Improved Al tolerance of saffron (Crocus sativus L.) by exogenous polyamines

The aluminum (Al) tolerance of saffron (Crocus sativus L.) in hydroponics and the method of improving Al tolerance were investigated. Compared with the Al-free control, saffron root elongation was decreased by 59.3 and 75% at 0.05 and 0.2 mM Al stress, respectively. At 0.5 mM Al stress, the root elongation was inhibited completely. Addition of 1 mM polyamines improved saffron root growth markedly at 0.2 mM Al stress. Putrescine (Put) showed better amelioration effect than spermidine (Spd) and spermine (Spm). The root elongation in Put treatment was only 15% lower than that of Al-free control. The alleviation of Al rhizotoxicity by polyamines might be attributed to lower Al content in the root tips, and subsequent less lipid peroxidation and oxidative stress. Higher activities of amine oxidases and Hydrogen peroxide (H₂O₂) content might decrease the effects of Spd and Spm on alleviating oxidative damage compared with that of Put.