甘蔗茎在弯曲荷载下的破坏

研究甘蔗的物理力学特性对研究甘蔗切割过程、设计刀片具有重要意义。该文采用三点弯曲方法研究甘蔗茎在弯曲荷载下的力学特性。以“桂林—1号”甘蔗为试验材料,在日本SHIMADZU公司生产的AG-I 50 AUTOGRAPH材料力学试验机上进行了蔗茎的弯曲试验。试验结果表明：蔗茎在弯曲荷载下主要有4种破坏形式：中性层裂纹、横向裂纹、底部纵向裂纹、不规则裂纹。其中基部和尾部试样以横向裂纹为主,其他部位的试样产生中性层裂纹;“桂林-1号”甘蔗基部弹性模量的平均值为1172 N/mm²,最大抗弯强度的平均值为46.5 N/mm²;基部去掉蔗皮后,弹性模量的平均值为1514.8 N/mm²,最大抗弯强度的平均值为42 N/mm²;蔗茎基部的弹性模量在剥皮前后有显著差异,且基部蔗芯的弹性模量明显高于未剥蔗皮基部的弹性模量。蔗茎基部的抗弯强度在剥皮前后无显著差异。     

Tissue and cell culture as AIDS to sugarcane breeding. I. Creation of genetic variation through callus culture

Summary Four-hundred and seventeen plants from 8 sugarcane varieties were selected among the 4600 plants that had been generated from calluses of shoot-apices, rolled young leaves and young inflorescences of 58 varieties. They were planted in the field (Field Test-II stage) in December, 1971 and examined for morphology, sugar content and chromosome number in the summer of 1972 and thereafter. The callus derivatives of the 8 varieties differed from their donors in the frequency of morphological changes: F146 (1.8%), N:Co310 (2.4%), F161 (4.8%), F164 (6.7%), F162 (7.4%), 56–2080 (15.8%), F170 (27.6%), and F156 (34.0%). Auricle length showed the greatest frequency of difference (8.6%); dewlap shape ranked next (6.5%); followed by hair group (6.2%); attitude of top leaves (1.9%). The sucrose content of callus derivative was increased over their donors by 2% to 12%. Chromosome number (2n) varied from 86 to 126 in the F156 derivatives in contrast with the donor's 114 whereas those of F164 varied from 88 to 108 as compared with the donor's 108. The derivatives of F146 generally centred around the original chromosome number of 110 and it is considered to be the most genetically stable cultivar. The cause of the occurrence of chromosome mosaicism in sugarcane is discussed. There was no apparent correlation between morphological modifications and changes in chromosome number.     

A binding protein for fungal signal molecules in the cell wall of Pisum sativum

In the plant cell wall of Pisum sativum seedlings, we found an NTPase (E.C. 3.6.1.5.) with ATP-hydrolyzing activity that was regulated by an elicitor and suppressors of defense from pea pathogen Mycosphaerella pinodes. The ATPase-rich fraction was purified from pea cell walls by NaCl solubilization, ammonium sulfate precipitation, and chromatography with an ATP-conjugated agarose column and an anion-exchange column. The specific activity of the final ATPase-rich fraction increased 600-fold over that of the initial NaCl-solubilized fraction. The purified ATPase-rich fraction also had peroxidase activity and generated superoxide, both of which were regulated by the M. pinodes elicitor and suppressor (supprescins). Active staining and Western blot analysis also showed that the ATPase was copurified along with peroxidases. In this fraction, a biotinylated elicitor and the supprescins were bound primarily and specifically to ca. 55-kDa protein (CWP-55) with an N-terminal amino acid sequence of QEEISSYAVVFDA. The cDNA clone of CWP-55 contained five ACR domains, which are conserved in the apyrases (NTPases), and the protein is identical to a pea NTPase cDNA (GenBank accession AB071369). Based on these results, we discuss a role for the plant cell wall in recognizing exogenous signal molecules.     

Inhibition of P-glycoprotein ATPase and its transport function of Helicoverpa armigera by morin, quercetin and phloroglucinol

Flavonoids (morin, quercetin and phloroglucinol) were tested for their ability to modulate the function of P-glycoprotein ATPase of the insecticide resistant pest Helicoverpa armigera (Ha-Pgp). Flavonoids in the presence of ethylparaoxon or cypermethrin significantly reduced both larval weight as well as survival rate 40-50%. Morin and quercetin inhibited the activity of Ha-Pgp ATPase by 80-90%, whereas phloroglucinol inhibited ATPase activity by 40% at 100 μM concentration. These flavonoids inhibited the verapamil, ethylparaoxon and cypermethrin-stimulated Ha-Pgp ATPase activity. Morin, quercetin and phloroglucinol binding were quantitated by quenching of the intrinsic Trp fluorescence of purified Ha-Pgp ATPase. Drug transport was monitored in proteoliposomes containing Ha-Pgp ATPase using the high affinity fluorescent substrate tetramethylrosamine (TMR) in real time. Addition of the morin and quercetin mediated the collapse of the TMR concentration gradient generated by Ha-Pgp ATPase. The inhibition studies on Ha-Pgp ATPase activity may contribute towards understanding new strategies of the pest to overcome insecticide resistance.     

应用RAPD技术研究甘蔗属及其近缘属种间亲缘关系

利用DNA随机扩增多态性(random amplified polymorphic DNA，RAPD)技术，研究了甘蔗属及其近缘属种间的亲缘关系。选择20个引物扩增，在得到的193个片段中，有3个片段是10个材料共有的，多态性达98％。聚类分析结果表明：甘蔗属可划分为两个组群，即热带种组群(包括热带种、印度种、大径野生种、中国种)和割手密种组群。该结论与Irvine的分类结果非常相似。     

螟黄赤眼蜂对甘蔗螟虫的控制效果

选新植蔗田和宿根蔗田释放螟苏赤眼蜂控制甘蔗螟虫,以甘蔗被害节为调查指标,结果发现,螟黄赤眼蜂对黄螟有较好的控制效果,而且在倒6-19节及全株的被害节率都明显低于对照,同时宿根蔗区又好于新植蔗糖区,在宿根蔗区对黄螟的防治效果尤其显著,全株的防效达到22.28%。     

于蔗种茎热水处理脱除宿根矮化病菌及其对再生苗的影响

50℃2h热水处理黑皮果蔗、黄皮果蔗和粤糖93-159双芽段种茎，结果表明：黑皮果蔗全部丧失出苗能力；黄皮果蔗出苗时间延迟，但最终出苗率与对照无差异；而粤糖93-159出苗率和出苗速度均不受影响。两个品种的热处理再生苗生长早期株高和茎径均显著低于对照，但随着生长时间的增加，这种差异逐渐缩小。采用高灵敏度的巢式PCR技术检测再生植株体内的宿根矮化病菌，在再生苗生长前期的120d内所有经热处理植株均呈阴性，其后部分植株呈阳性，至播种200d时，黄史果蔗阳性率为50％，粤糖93-159阳性率为100％。试验还发现，种茎热水处理能增强再生植株中后期抗旱能力。本研究指出，虽然种茎热水处理能减少生长早期再生苗体内宿根矮化病菌含量但难以实现所有种茎完全脱菌。在进行脱菌效果评价时，要对生长中后期的再生苗进行检验；生产上采用该措施防病，要充分考虑不同品种耐热性能的差异。     

Distinguishing sporulating and nonsporulating lesions as a method for evaluating the resistance of sugarcane genotypes to orange rust

Sugarcane breeding programmes rank the resistance of genotypes to Puccinia kuehnii, causal agent of orange rust, according to levels of disease severity. However, during the screening stages, this method of assessment can lead to precipitous elimination of genotypes with promising agronomic traits but showing mild symptoms of rust such as flecks or lesions that do not produce spores. This study aimed to propose a new method to classify the resistance of sugarcane genotypes to orange rust by counting sporulating lesions. Five sugarcane varieties with different levels of resistance to P. kuehnii were inoculated with two pathogen populations under controlled conditions. The disease severity (SEV), total number of lesions (TNL), and total number of sporulating lesions (TNSL) were evaluated in a 20 cm leaf fragment from the most diseased leaf. The TNL and TNSL evaluations were performed at 11, 16 and 21 days after inoculation (DAI) and SEV at 21 DAI. The thresholds of 80% and 8% of sporulating lesions (SL) separated susceptible from the intermediate varieties and intermediate from the resistant ones, respectively. It is proposed that the method of counting sporulating lesions be used in screening genotypes for resistance to P. kuehnii in sugarcane breeding programmes.     

The toxicity and physiological effect of neem limonoids on Cnaphalocrocis medinalis (Guenée) the rice leaffolder

The effect of neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione, and deaceytlnimbin on gut enzyme activity of the rice leaffolder larvae was investigated. When fed a diet of rice leaves treated with limonoids in bioassays, gut tissue enzymes—acid phosphatases (ACP), alkaline phosphatases (ALP), and adenosine triphosphatases (ATPase) activities of rice leaffolder (Cnaphalocrocis medinalis) larvae are affected. Azadirachtin was most potent in all experiments. Larvae that were chronically exposed to limonoids showed a reduction in weight (59-89%) and exhibited a significant reduction in ACP, ALP, and ATPase activities. These results indicate neem limonoids affects gut enzyme activities. These effects are most pronounced in early instars.