Effect of Aluminum and Silicon in Solution on the Growth of Rice (Oryza sativa L.) uspension Cells

Cells of two indica rice (Oryza sativa L.) varieties, one aluminum-tolerant (IAC3), and the other aluminum-sensitive (IR45), were grown in suspension culture in a medium with or without Al (0-800 µM), Si (0-2,000 µM), or Al and Si in combination as well as in R2 medium as control. The influence of Al or Si on cell growth was evaluated based on the growth of the cells in the treatment medium as well as in the R2 medium and compared with the effect on rice seedlings. Similar responses were observed for the cells and the seedlings; Al treatment resulted in a significant reduction of cell growth in both varieties, and the growth was reduced with the increase of the Al uptake by the cells. IAC3 was more tolerant to Al and it absorbed more Al than IR45. On the contrary, Si alone had almost no effect or exerted a negligible effect on the cell growth in both varieties and Si was hardly absorbed by the cells. There was a slight alleviative effect of Si on Al toxicity in the suspension cells of IR45, whereas, a considerable ameliorative effect in the seedlings. The content of total Al and of AI insoluble in citric acid in the cells were higher in the sole Al (800 µM) treatment than in the Al-Si combination treatment. This tendency was also observed in aluminon staining. The differences in the alleviative effects of Si and the uptake of Al and Si between the suspension cells and seedlings may have resulted from the presence of roots and morphological differences in the apoplastic tissues.     

硅对籼稻和粳稻品种磷积累的影响

硅(Si)可以改善磷(P)的营养,但是其内在机制尚不明确。本研究以4个籼稻和3个粳稻品种为研究对象,通过水培试验探究硅对不同水稻品种磷积累的影响。在营养液中添加硅显著降低了籼稻和粳稻品种的地上部磷含量,但几乎不影响根部磷含量。加硅处理不影响所有供试水稻品种的磷吸收及磷从根系向地上部的转移,但提高了磷的利用效率,增加了植株P/Mn和P/Zn比率。磷转运蛋白(PT)基因表达分析表明,在粳稻品种中只有OsPT6被硅下调,而OsPT6在籼稻品种中没有显著性变化;其他PT基因的表达不受硅的影响。由此,硅对不同水稻品种的磷积累有不同的影响,磷利用率的提高可能归因于较高的P/Mn和P/Zn比率,从而导致植物中较高的有效磷。     

不同水稻品种磷利用效率与耐铝性的关系研究

铝毒和磷缺乏是酸性土壤上作物生产的主要限制因子。本研究中我们探究了5个粳稻和5个籼稻品种的磷利用效率和耐铝性之间的相互关系。结果表明,粳稻品种的耐铝性显著高于籼稻品种。对于耐铝性强的水稻品种,施加磷肥后地上部生物量显著增加,而铝敏感的品种对磷肥响应较小,这可能是由于其耐铝性差而酸性土壤中的铝毒导致根系结构和功能受损,从而影响养分的吸收和利用。不同水稻品种的耐铝性和磷吸收效率呈正比而与磷利用效率呈反比,且粳稻的地上部磷浓度及磷吸收效率高于籼稻,但磷利用效率则低于籼稻。这些结果对于酸性土壤中筛选耐铝和磷高效利用的水稻品种具有重要意义。     

Varietal diversity of upland rice in sensitivity to aluminium

A rapid and simple nutrient addition technique was used for evaluating Al tolerance of six local upland rice (Oryza sativa L.) cultivars (BG35, BR21, DA25, DA26, DA14, and DA22) from Bangladesh and three IRRI rice, IR46, IR97, and IR45, cultivars from the Philippines. The plants were grown for 21 days with Al (0 μM, 140 μM, 280 μM or 560 μM) at pH 4.1. The roots were more affected by Al than the shoots. In rating cultivars for Al sensitivity, relative shoot weight (RSW) was found to be the best parameter due to the severe damage of the roots, irrespective of Al sensitivity. The cultivars were rated as Al tolerant (BG35, BR21, DA25, and DA26), mid‐tolerant (DA14, DA22, and IR46) and sensitive (IR97 and IR45) . More Al was retained in the roots of tolerant cultivars than in the mid‐tolerant or sensitive cultivars. In shoots, the Al concentration of tolerant cultivars was less than in the mid‐tolerant or in the sensitive cultivars and the inhibition of growth was proportional to Al concentration irrespective of Al tolerance. Therefore, the variation among cultivars in Al sensitivity could be related to the capacity of roots to retain Al from transport to the shoots.     

Effects of low aluminium levels on growth and nutrient relations in three rice cultivars with different tolerances to aluminium

Reports on varietal diversity of upland rice in relation to relatively low aluminium (Al) levels are limited. Therefore, effects were examined of 35, 70, and 140 μM Al on plant growth and uptake of macro‐ and micro‐nutrients (K, P, Ca, Mg, Fe, Zn, Cu, and Mn) and their distribution in three upland rice (Oryza saliva L.) cultivars (BG35, DA14, and IR45) with different Al sensitivity. After an initial growth period of 5 days without Al, the plants were grown for 21 days in nutrient solutions containing Al at pH 4.1. Cultivar BG35 showed the highest and IR45 the lowest tolerance to Al when fresh weights of shoots or roots were considered. Except for IR45 at 140 μM Al, total dry weight was unaffected by Al, and the cultivars could not be clearly distinguished with respect to Al tolerance. Net Al uptake rate was higher in Al tolerant BG35 than in DA14 or IR45. Conversely, in IR45 the absorbed Al was rapidly transported to the shoots and accumulated there. In BG35, net P and Ca uptake rates in Al‐treated plants were high enough to maintain the P and Ca status of the shoots at all Al levels. Irrespective of Al sensitivity, there was a general depression of internal Mg concentration in Al‐reated plants. The Fe, Zn, Cu, and Mn concentrations of the plants were not negatively affected by Al in any of the cultivars.     

Response of cotton cultivars to aluminum in solutions with varying silicon concentrations

Abstract

Cotton (Gossypium hirsutum L.) is extremely sensitive to Al toxicity. Increasing Si concentration in solution has been reported to alleviate AI toxicity. In this investigation the effects of varying Si concentrations (700, 1400, and 2800 μM Si) on reactive Al (defined as Al reactive with aluminon during 10‐s reaction time, without acidification and heating) was studied in solutions containing either 50, 100 or 200 μM Al during 50 d of aging. An increase in Si concentration had negligible effects on the reactive Al in solutions with 50 or 100 μM Al. However, in solutions with 200 μM Al the reactive Al decreased by 6 to 15% with an increase in Si concentration from 0 to 2800 μM.

The effects of either 700, 1400 or 2800 μM Si on root growth of Coker 208, Coker 315, DPL 90, McNair 235, Stoneville 506 and Tifcot 56 cotton cultivars were investigated in solutions containing either 0, 10, 20 or 40 μM Al with 500 μM Ca at pH 4.5. In solutions containing no Al, addition of 700 μM Si improved root growth by 69–87% in Coker 315, DPL 90 and McNair 235 cultivars but not in the other cultivars. In solutions containing 10 μM Al, an increase in Si concentration from 0 to 2800 μM improved the root growth by 15–17% in DPL 90 and McNair 235 cultivars only. An increase in Si additions failed to improve root growth of any of the cultivars in solutions with 20 or 40 μM Al.     

Aluminium sensitivity of two upland rice cultivars at various levels of nutrient supply

Two upland rice (Oryza sativa L.) cultivars with high (IR45) and low (BG35) aluminium (Al) sensitivity were selected to investigate the influence of Al on growth and uptake and distribution of macronutrients [potassium (K), phosphorus (P), calcium (Ca), and magnesium (Mg)] when the plants were grown at various levels of nutrient supply. The plants were grown for 21 days with or without 140 μM Al at pH 4.1. Nutrients were supplied with 2.5, 5.0, 10, or 15% relative increase/day relative nutrient addition rate (RNR), according to a nutrient supply program. In this range of nutrient supply rates, the degree of Al sensitivity in the two rice cultivars was not markedly affected, except for root growth in BG35 that was more inhibited at low RNRs than at high RNRs. Regardless of nutrient supply rate, Al was mainly confined to the roots in both cultivars. However, the concentrations of Al in the shoots was consistently lower in BG35 than in IR45. Different Al sensitivity in BG35 and IR45 was associated with different influence on uptake and distribution of P and Ca. Uptake of Mg was drastically inhibited by Al at all nutrient supply levels in both cultivars. Uptake and distribution of K were not negatively affected by Al.     

Comparison of the physicochemical properties and ultrastructure of japonica and indica rice grains

The physicochemical properties and ultrastructures of japonica vs indica rice varieties and waxy vs nonwaxy rice varieties were compared. The viscogram values of the indica varieties were significantly higher than those of the japonica varieties. The gelatinization temperatures, breakdown, and setback were significantly lower for waxy than for nonwaxy rice varieties. Japonica rice exhibited lower hardness but higher adhesiveness than indica rice. The air space between individual starch granules was larger for waxy than for nonwaxy rice. The starch granules were compact in japonica rice, while the compound starch granules of indica rice were much smaller than those of japonica rice and were scattered widely in the endosperm. The protein bodies in japonica rice were concentrated near the cell wall, whereas those in indica rice were scattered around amyloplasts. These results suggest that the ultrastructure of rice affects the texture of the cooked product.     

硅对减轻水稻的铝胁迫效应及其机理研究

通过分析溶液中Al离子形态变化和根内Al的分布 ,探讨Si对减轻水稻Al胁迫的效应及其机理。结果表明 ,pH4.5的溶液培养条件下Al在短时间内即可明显地抑制水稻根系的生长 ,加入不同形态的硅酸可有效地减轻Al对水稻的胁迫 ,根的伸长量接近或达到对照处理的水平。加Si降低了溶液中单质态Al离子的浓度 ,改变了溶液中Al的形态。分子筛柱层析分离和离子交换树脂吸附分析发现 ,溶液中产生了新的Al化合物 ,阳离子交换态Al的比率由 78%降低到 48% ,而交换态Si的比率由 0 %增加到 20%。Al主要聚集于根质外体特别是细胞壁中 ,加入低分子态硅酸增加了根全Al和质外体Al的含量 ,但是却降低了细胞壁Al的含量 ,而加入高分子态硅酸明显地降低了根全Al、质外体、共质体和细胞壁Al的含量     

Silicon Requirement of Coarse and Fine Varieties of Rice

ABSTRACT

Silicon (Si) provides extra strength to plants against lodging. A hydroponic study was conducted to compare Si requirements of three high yielding, nitrogen (N) responsive, coarse varieties of rice (KSK-133, PK-3717-12, and IRRI-6) with four low yielding, lodging susceptible, fine varieties of rice (BAS-191, BAS-385, BAS-370, and PK-3300). Two-week-old uniform seedlings were grown in half strength Johnson's nutrient solution containing 0, 25, 75, and 150 mg Si kg^{? 1} as sodium silicate. The plants were allowed to grow for 45 days after transplanting. Silicon application significantly (P ≤ 0.01) increased root and shoot dry matter production in all the rice varieties. The maximum shoot dry matter production occurred at 75 mg Si kg^?1 and decreased uniformly in all the rice varieties at 150 mg Si kg^{? 1}. However, growth response to Si application varied significantly (P ≤ 0.01) among various rice varieties. Root: shoot growth ratio, varying from 0.11 to 0.15, did not follow any trend. Different rice varieties and Si addition had a significant (P ≤ 0.01) main and interactive effect on concentration and total uptake of Si in rice root and shoot. Relative increases in Si content, both in shoot and root, were gradual and several fold with increasing rates of Si application. The effect was more pronounced in Basmati varieties (BAS-198, BAS-385, and BAS-370) than other varieties. A 0.91 mg Si g^{? 1} plant tissue was optimum for growth of KSK-133 (coarse), which was significantly higher than the optimum level, 0.62 mg Si g^{? 1} plant tissue, for Bas-370 (fine). However, further verification of the results is warranted under field situation.     

Arsenic uptake is suppressed in a rice mutant defective in silicon uptake

Possible mechanisms of the effects of silicon (Si) on arsenic (As) uptake were explored using a wild‐type rice and its low‐Si mutant (lsi1). Hydroponic experiments were carried out to investigate the effects of internal and external Si on the As accumulation and uptake by rice in excised roots (28 d–old seedlings) and xylem sap (61 d–old plants). The presence of Si significantly decreased the As concentrations in both shoots and roots of the wild type but not in the mutant with 13.3 μM–arsenite or 10/20 μM–arsenate treatments. The Si‐defective mutant rice (lsi1) also showed a significant reduction in arsenite or arsenate uptake. Moreover, As concentrations in xylem sap of the wild type were reduced by 51% with 1 mM Si– and 15 μM–arsenate treatments, while Si had no effect on As concentrations in the xylem sap of the mutant. Arsenic‐species analysis further indicated that the addition of 1 mM Si significantly decreased As(III) concentrations but had little effect on As(V) concentrations in the xylem sap of the wild type with 15 μM–arsenate treatments. These results indicated that external Si‐mediated reduction in arsenite uptake by rice is due to the direct competition between Si and arsenite during uptake. This is because both share the same influx transporter Lsi1. In addition, internal Si‐mediated reduction in arsenite uptake by rice is due to competition of the Si/arsenite efflux transporter Lsi2 during the As(III)‐transportation process. Silicon also inhibited arsenate uptake by rice. It is proposed that this could actually be due not to the inhibition of arsenate uptake per se but rather the inhibition of arsenite transformed from arsenate, either in the external solution or in rice roots.     

硅对柱花草铝毒的解毒作用

为了解硅在解除豆科作物铝毒方面的作用,本文以5个品种的柱花草为材料研究了硅对铝胁迫条件下的植物根伸长及膜脂稳定性的影响。研究结果表明,在铝（30μmol／L）胁迫条件下柱花草根伸长受阻、根尖丙二醛（MDA）含量和抗氧化酶（POD,CAT）活性显著增加,而硅（1．4mmol／L）处理增加根中硅的含量而降低了铝对根伸长、MDA含量和抗氧化酶活性的影响,且铝处理前12h供给的硅和前处理溶液及铝溶液中均加硅处理的影响均显著;在不加硅条件下西卡品种的耐铝性显著低于其它品种,而经硅预处理的植株和在预处理及铝处理期间均供应硅的植株的耐铝性不同品种问的差异不显著。这些结果表明,硅能提高柱花草的耐铝能力并影响品种间耐铝差异性。     

水稻穗期活体植株对潮霉素的敏感性分析及突变体选育

携带潮霉素磷酸转移酶基因(HPT)的转基因作物细胞和组织对抗生素潮霉素具有一定耐性,是作物尤其是单子叶作物遗传转化中常用的选择基因。本研究旨在建立一种活体植株潮霉素抗性快速鉴别技术,用于转基因育种和相关研究。在始穗期前后,用不同浓度潮霉素B溶液(25～100mg/L)喷洒常规及转基因水稻植株,考察叶片和谷粒的中毒症状。发现常规水稻在高于50mg/L的潮霉素溶液处理后,叶片出现褐色斑点,稻穗部分谷粒颖壳呈黄褐色的中毒症状,叶片斑点和黄褐色谷粒的数量均随剂量增大而增加。经100mg/L潮霉素处理后,籼稻品种嘉优99和C10剑叶每平方厘米平均斑点数目为21.1和19.2个,穗上黄褐色谷粒比例分别达27.6%和23.5%;粳稻品种嘉优5号和R5叶片中毒斑点数为11.8和10.7个,黄褐色谷粒比例分别为11.2%和11.9%,表明2份籼稻材料较2份粳稻材料对潮霉素更为敏感。在上述浓度范围内,携带HPT的转Bt基因水稻克螟稻1号均未出现中毒症状。对γ射线诱变处理克暝稻的M2群体(共12万株)穗期喷施100mg/L的潮霉素B溶液,从中筛选到42株潮霉素敏感型突变体,组织化学法分析表明这些植株具有β-葡萄糖苷酸酶GUS活性。对能够取到较嫩叶片的14个单株采用离体叶片法进行抗虫性鉴定,证明这些植株对二化螟仍然表现高抗。上述结果表明,在始穗期喷施100mg/L潮霉素溶液,潮霉素敏感植株可出现明显、直观的中毒症状,可以在活体植株水平上有效鉴别植株是否携带HPT,可用于育种中转基因植株的筛选或转基因安全评估中植株的鉴别。     

大田生产条件下不同品种水稻植株中镉的分布特点

通过4个水稻品种在大田生产条件下的试验,研究分析了水稻植株Cd积累和分布的特点。结果表明,水稻的根系是吸收Cd的主要器官,也是Cd的主要储存场所,无论在水稻分蘖期还是成熟期都很明显;在水稻成熟期,籽粒（糙米）中Cd的含量显著地低于其他器官,水稻植株器官中Cd的分布情况大致为：根〉鞘＞叶＞茎＞糙米,但随着品种的不同而有所变化;根据4个水稻品种在成熟期的植株Cd积累量的分析,9311是植株高累积Cd的水稻品种,Jia－48和Jia－51的糙米中Cd的积累很低;水稻品种间对于Cd的吸收和累积能力有显著的差异,但水稻类型间（粳稻与籼稻间）Cd含量没有显著差异,因此不能按照水稻类型来选育糙米中低Cd积累品种,应针对品种选育出糙米中低Cd积累的高产优质水稻品种。     

双季直播稻品种搭配模式研究

为探明双季直播条件下不同早晚稻搭配对生育特性、产量形成和稻米品质的影响,本研究以3个早稻品种(柒两优2012、潭两优83、湘早籼45号),2个晚稻品种(甬优1538、泰优398)为试验材料,设置早籼晚粳(M1):柒两优2012—甬优1538;早籼晚籼(早晚兼用,M2):柒两优2012—柒两优2012;早籼晚籼(早晚不兼用,M3):潭两优83—泰优398,并以双季兼用常规籼稻湘早籼45号为对照(CK),分析不同早晚稻双季直播的周年生育期、群体质量、产量构成、周年产量、稻米品质与稻米淀粉RVA特征谱。结果表明,不同搭配模式的晚稻均安全齐穗,周年生育期以M1最长(222 d),较CK延长了16 d;周年总产量M1最高(14.82 t·hm^-2),较CK增产1.56 t·hm^-2,增产率为11.76%;其次是M2,周年总产量为14.29 t·hm^-2,较CK增产1.03 t·hm^-2,增产率为7.77%;M3周年总产量比CK增加了5.28%。对双季直播不同搭配模式的群体质量和产量构成特征分析表明,周年产量较高的搭配模式具有抽穗期-成熟期干物质积累量大,孕穗期-成熟期叶面积指数(LAI)大,早晚稻穗大、结实率和日产量高等特点。M1、M2和M3的晚稻稻米品质及稻米淀粉RVA特征谱优于CK,而早稻无明显差异。总体而言,M1搭配模式在保证周年产量的前提下,稻米品质优于其他搭配。本研究结果可为双季稻轻简化栽培提供参考。     

水稻黑条矮缩病抗病品种的筛选及其抗病机制初探

为有效防治水稻黑条矮缩病的大面积发生,本研究通过室内大量饲养无毒灰飞虱,饲毒后对浙江省20个主栽水稻品种进行传毒,人工接种水稻黑条矮缩病毒(rice black-streaked dwarf virus,RBSDV) 后移栽田间,观察病苗症状,测量株高,统计发病率并分析病毒含量。结果表明,籼稻品种深两优5814和Y两优302的抗性较强,粳稻品种淮5和秀水14的抗性较弱。此外,病毒侵染后,籼稻品种深两优5814和Y两优302的OsMYC2和OsNPR1的mRNA表达水平显著高于粳稻品种淮5和秀水14。上述结果表明,籼稻品种深两优5814和Y两优302抗病毒能力与其体内茉莉酸(JA)和水杨酸(SA)激素水平相关,这为今后筛选抗RBSDV材料提供了新的策略和思路。     

介质pH与氮形态对不同水稻基因型根部通气组织形成的影响

在溶液培养条件下研究了不同介质pH和氮形态对5种不同的水稻(Oryza.sativa.L.)基因型(常规籼稻、杂交籼稻、常规粳稻、杂交粳稻和旱稻)根部通气组织形成的影响。结果表明,不同形态的氮与不同介质pH对水稻根通气组织形成的影响存在基因型差异。以NH4+-N为单一氮源时,低pH(pH.4.5)更有利于籼稻根的通气组织形成,而粳稻和旱稻根通气组织的形成受介质pH的影响不明显。以NO3--N为单一氮源时,近中性条件(pH.6.5)更有利于粳稻和旱稻根的通气组织形成,介质pH对籼稻根通气组织形成的影响未显示出明显差异。低pH条件下且以NH4+-N为单一N源时,稻根皮层处更易形成通气组织,可能是植物为了减轻低pH条件下铵毒害而产生的一种适应性机制。     

不同水分条件下水稻根解剖结构的比较分析

在旱作和淹水两种培养方式下,研究了5种基因型水稻(Oryza.sativa.L.)(常规粳稻、杂交粳稻、常规籼稻、杂交籼稻和旱稻)幼苗根系解剖结构的差异。结果表明,两种水分条件下,水稻根通气组织的形成和皮层厚壁细胞的形态均存在基因型差异。5种基因型间,淹水条件下杂交粳稻根形成通气组织的时间最晚,根皮层厚壁细胞形态上的差异在常规粳稻和常规籼稻之间表现得更为明显;旱作条件下旱稻的根通气组织形成较其他基因型晚,常规粳稻根皮层厚壁细胞排列疏松,细胞壁加厚程度小。与淹水条件相比,旱作条件下杂交稻根通气组织形成较迟,常规粳稻根皮层厚壁细胞排列较疏松。     

硅对水稻防御性关键酶活性的影响及其与抗稻瘟病的关系

通过室内溶液培养试验,研究了硅酸盐对接种稻瘟病菌后水稻的病情指数、植株生物量、过氧化物酶（POD）、多酚氧化酶（PPO）和苯丙氨酸解氨酶（PAL）活性的影响。结果表明,施硅能显著降低水稻稻瘟病的发病率和病情指数,防治效果达60.59%;显著减轻稻瘟病对水稻地上部的危害,干物质量显著高于不施硅处理,但对地下部生长影响不明显;接种后水稻叶片POD活性均升高,在第5 d达到最大值,施硅处理显著低于不施硅处理,与稻瘟病抗性成负相关;水稻叶片PPO活性在接种后第5 d达到峰值,从第4 d开始施硅处理显著高于不施硅处理;接种后水稻叶片的PAL活性快速升高,在第24 h达到最大值,施硅处理显著高于不施硅处理,是其1.44倍。说明硅能提高防御性关键酶的活性,参与水稻本身防卫机制,通过一系列的生理生化作用来增强水稻的抗性。