距离高恩高速沙湖东出口大约5 km,恩平基龙实业有限公司坐落在一片长势喜人的稻田和郁郁葱葱的群山中.我们穿过农田和鱼塘,在办公楼前见到了陈钢基总经理. 陈总告诉我们,基龙实业自2002年成立,迄今已有21年了.最初将养殖场选在恩平,主要是基于环保、交通等因素综合考虑,这里青山环绕、资源丰富,而且水陆交通便利、四通八达.

1979年,作为改革开放的前沿地,深圳经济特区掀起了一股前所未有的发展浪潮,中国饲料现代工业也开始蓬勃发展.1984年,深圳华宝饲料厂应运而生,可以说它背负了中国第一代饲料工业品牌的重任.历经时代的风吹雨打,至今华宝饲料有限公司已经36年了,它见证了广东饲料业的萌芽、成长和强大.为此,我们采访了惠州市华宝饲料厂(以下简称“华宝”)钟志平总经理.

【Objective】Ribosome inactivating proteins (RIPs) are a group of important proteins that inhibit the growth of plant pathogens and development of insects. Cloning the RIPs genes is very important for research their resistant function and applications.【Method】A novel DNA fragment coding RIP was isolated from Cassia occidentalis by applying a PCR strategy in which a pair of universal degenerated primers deduced from the two blocks with strong conserved amino acid regions in multiple plants was used. Then the full length cDNA (CassinⅠ) of the fragment was obtained by rapid amplification of cDNA ends【.Result】The full length of CassinⅠwas 882 bp. Compared with two kinds of typical RIP from Cucurbitaceae, the homologies of the deduced amino acid sequences of CassinⅠshared 58.2% and 34.7% with that of β-luffin and Trichosanthin (TCS), respectively, and there was no significant homology compared with other sequences of RIPs in GenBank. Result of multiple alignment about TCS, β-luffin and CassinⅠshown that 9 amino acid residues forming the active site of the TCS were conserved in CassinⅠ except that 2 residues was different. All the RIP active sites of CassinⅠ sequence were contained in P1/P2 amplification region.【Conclusion】It is the first report that a novel RIP gene was cloned from the Cassia occidentalis.. The results reported in this paper have laid a foundation for further studies of RIP gene function and development of transgenic plants to control plant diseases and insects.

Six novel DNA fragments coding for ribosome-inactivating proteins(RIPs) were isolated from Araceae macrorrhiza,Nicotiana tobaccum,Agavaccae agave,Cassia occidentalis and Musa spp.respectively,with PCR strategy by using a pair of universal degenerated primers deduced from the two blocks with strong conserved amino acid regions of RIPs.Amino acids sequences deduced from the six DNA fragments were analyzed by BLAST,there was no significant homology compared with the sequences in Genbank except for RIPs from different plants.Compared with the corresponding regions of 2 typical RIPs from Cucurbitaceae,the homologies of the deduced amino acid sequences of 6 novel RIPs gene fragments shared 97.2%,98.5%,97.9%,89.4%,97.9%,97.2% with that of β-luffin,and 63.6%,64.5%,64.1%,60.8%,64.8%,63.6% with that of trichosanthin(TCS) respectively.Result of multiple alignment about TCS,β-luffin and the six amino acid sequences showed that amino acid residues forming the active site of N-glycosidase located in 10,9,11,11,9,10 of the TCS were conserved in them except that 1～2 residues were different.All the active site of the six novel DNA fragments were contained in P1/P2 amplification region.

Cassin, the new gene of ribosome-inactivating protein (RIP) isolated from Cassia occidentalis, was inserted into expression vector pBI121 to produce plant expression vector pBI121-cassin (Figs.1, 2). pBI121-cassin was introduced into tobacco cultivar 'K326' by the Agrobacteriurm tumefaciens transformation method and more than 100 independent transformants were obtained. Southern blot hybridization analysis showed that a single gene locus was inserted into the chromosome of the transgenic tobacco lines (Fig.5) and PCR analysis of segregation population of progeny indicated that the inheritance of transgene was dominant in transgenic lines (Fig.4, Table 1). Results of RT-PCR and Northern blot hybridization analysis showed that transgene could be transcribed correctly (Figs.5, 6) . Three self-pollination lines of transgenic T(1) and T(2) were challenged with TMV at different concentration titers by mechanical inoculation. The transgenic lines exhibited different levels of resistance to TMV with the nontransgenic plants. After both titers of TMV concentration were inoculated, transgenic lines were considered as the highly resistant type with a delay of 4-13 d in development of symptoms and 10%-25% of test plants were infected, while nontransgenic control plants were susceptible typical symptoms on the newly emerged leaves (Table 2). One T(2) line, T(2)-8-2-1, was regarded as an immune type because it did not show any symptoms during 70 d and all plants were shown to be virus free by ELISA tests.

从华中农业大学草坪草的狗牙根Cynodon dactylon上分离得到引起该草坪草黑斑病的病原菌,并对该病原菌进行了形态学观察、致病性测定、rDNA-ITS序列分析以及生物学特性的研究.研究结果表明:该病原菌在PDA培养基上培养7 d后菌落呈墨绿色,菌丝有隔,分生孢子有3个隔膜,中间两细胞较大,弯曲,两端细胞颜色较浅.孢子平均大小为24.94 μm×10.30 μm.其rDNA-ITS序列表明,分离的病原菌与Genbank中的Curvularia verruculosa的同源性是99%,结合形态学特征和致病性测定认为该菌为C.verruculosa.生物学特性研究表明,该菌丝在pH值5.0～9.0的PDA上均能生长,最适碳源为可溶性淀粉,最适氮源为KNO3.菌丝生长的致死温度为70 ℃ 15 min,孢子萌发的致死温度为75 ℃ 15 min.这是C.verruculosa引起狗牙根黑斑病的首次报道.