Variation in growth rates and aggressiveness of naturally occurring self‐fertile and self‐sterile isolates of the wilt pathogen Ceratocystis albifundus

Ceratocystis albifundus is the most important fungal pathogen of black wattle (Acacia mearnsii) grown in plantations in southern and eastern Africa. It is a homothallic fungus but also undergoes unidirectional mating type switching. As a result, the ascospore progeny can be either self‐fertile or self‐sterile. The only apparent difference between these mating types is the deletion of the MAT1‐2‐1 gene in self‐sterile isolates. There is some evidence suggesting that self‐sterile isolates grow more slowly than self‐fertile isolates, but this has not been tested rigorously. The aim of this study was to determine whether self‐sterile isolates are less fit by examining growth rate, relative germination rate and pathogenicity. Five self‐sterile isolates were generated from each of five self‐fertile isolates of C. albifundus and these 30 isolates were compared. The results showed that the self‐sterile isolates grew consistently slower and were less pathogenic than the self‐fertile isolates. The germination ratio of self‐fertile to self‐sterile isolates from single ascospores collected from the ascomata of five self‐fertile isolates was on average 7:3. This could be a consequence of the self‐sterile isolates having a lower germination rate. This observation, and the lower growth and pathogenicity levels, suggests that self‐sterile isolates are not likely to compete effectively in nature, raising intriguing questions regarding their role and value to C. albifundus and other fungi having a similar mating system.     

利用性信息素迷向技术防治桃园梨小食心虫的效果与分析

为了绿色防控桃园梨小食心虫的为害,进行了性信息素迷向技术防效实验。连片100×667m2以上的桃园,平均亩悬挂梨小食心虫迷向丝60枚,迷向丝对梨小食心虫各代成虫的迷向率可达96%以上,且持效期在4个月以上,对各代折梢防效在94%以上,蛀果防效在96%以上,全年用药次数减少4~7次。结果表明,该技术对桃树整个生育期梨小食心虫的为害具有良好的控制作用,可有效减少农药防治次数和用药量,值得大面积推广应用。     

Evidence of Inheritance of Intrahepatic Portosystemic Shunts in Irish Wolfhounds

Background: The etiogenesis of congenital portosystemic shunt in dogs is not understood. In Irish Wolfhounds, intrahepatic portosystemic shunt (IHPSS) is thought to be hereditary, but the mode of inheritance is unknown.
Objectives: To document the genetic background and investigate the potential mode of inheritance of IHPSS in Irish Wolfhounds.
Animals: Three mature, privately owned, affected siblings and their progeny produced in 2 litters.
Methods: Prospective, observational study. Two test matings of 1 affected sire with 2 of his affected sisters were used to determine the inheritance pattern. Affection status was determined by measuring venous blood ammonia concentrations, detection of the shunt by ultrasonography and confirmation during surgical attenuation of the intrahepatic shunting vessel.
Results: In 1 litter of 5 pups all had an IHPSS. In the other litter 5 of 11 pups were affected. Both left- and right-sided shunts occurred in both litters. No sex predisposition was evident among affected dogs.
Conclusions and Clinical Importance: Our results show that IHPSS in Irish Wolfhounds is a familial disorder that is likely genetic. It is unlikely that the mode of inheritance is monogenic. A digenic, triallelic trait could explain the observed occurrence of IHPSS but other modes of inheritance cannot be excluded.     

杂种优势的进化意义探析——以适合度对随机交配群体遗传多样性的贡献为依据

从群体遗传的角度将杂种优势与近交衰退的定义进行类比,认为杂种优势应该用适合度来综合衡量。建立数学模型,推导出随机交配群体3种基因型RR、Rr、rr在不同适合度下的平衡状态,揭示杂种优势是群体中复等位基因存在的先决条件。发现杂种优势通过提高杂合个体的适合度,避免淘汰不同类型的基因,从而保护群体的遗传多样性,使群体具有较强的自我调节和进化潜力;让个体意义上的适应与群体层次的适应协调一致,深化了达尔文的个体选择思想。     

昆虫交配行为、繁殖适度和性信息素在国内的研究进展

昆虫行为学是一门颇受重视的热门学科,主要包括昆虫交配行为、繁殖适度及性信息素等方面的研究。文章概述了昆虫多次交配、延迟交配等有关昆虫交配行为中的问题,并从昆虫的多次交配、延迟交配、不同日龄、光照、温度等对昆虫交配行为和繁殖适度的影响做了综述;指出昆虫行为学的研究已在害虫预报和防治方面得到广泛应用,在有机农业中的应用有着巨大的潜力,对农业生产将会产生不可估量的作用。     

鹅掌楸不同交配组合子代苗期生长变异及遗传稳定性分析

种间杂交和杂种优势利用是鹅掌楸Liriodendron spp.遗传改良的重要途径。报道了鹅掌楸不同交配类型和不同交配组合子代的生长表现及遗传稳定性,为杂交鹅掌楸品种选育提供参考依据。参试鹅掌楸交配组合39个,分属3种交配类型（种间杂交、种内杂交及回交）,以鹅掌楸自由授粉子代为对照,在3个试验点进行子代测定。通过对各交配组合子代2年生苗进行苗高和地径比较分析。结果表明,就苗期生长量而言,鹅掌楸种间杂交、种内杂交及回交均显著高于对照。其中,种间杂交组合子代生长最好,种内杂交组合子代次之,回交组合优势较小。种间正反交组合间差异不显著,而同一交配类型的不同组合间差异达极显著水平（P〈0.01）。表明在鹅掌楸杂种优势利用时,应重视杂交亲本的选择。同时,利用Eberhart和Russell模型评价了各杂交组合的生长适应性与遗传稳定性,并初选出生长快、适应性强、综合性状较优的组合J×L,而组合BK1×H和Z×WYS1生长较快,但稳定性较差。表5参16     

棉铃虫和烟夜蛾生殖行为比较研究

在(27±1)℃,光周期14L:10D的条件下对棉铃虫(Helicoverpa armigera)和烟夜蛾(Helicoverpa assulta)的生殖行为进行了比较研究.结果表明:(1)2种夜蛾雌蛾或雄蛾的交配能力之间均无显著差异;3日龄蛾的交配率较高,6日龄前棉铃虫的交配率均显著高于烟夜蛾;不同蛾龄下烟夜蛾的交配...     

部分表型交配群体的信息熵

研究了在世代交替中群体总有50%的个体表型同型交配、50%的的个体随机交配的大盂德尔群体,推得各世代基因型频率分布、母子间基因型频率分布,给出各世代基因型信息熵、母子间基因型联合信息熵的算式,并证明二者随世代交替逐渐减少,最终趋于定值,群体最终达到一种远离Hardy-Weinberg平衡的非平衡定态.模拟结果验证了所得...     

稻曲菌交配型初探

 稻曲菌（有性态：Villosiclava virens;无性态：Ustilaginoidea virens）有性繁殖产生的子囊孢子是水稻稻曲病可能的初侵染源之一,交配型基因座对真菌有性繁殖中的性别控制起着决定性作用。为进一步揭示稻曲菌的有性繁殖方式,本研究首次克隆了稻曲菌交配型基因mat1-1-1的α-结构域（α-domain）相应核苷酸序列,发现其与麦角菌科真菌Cordyceps militaris、Cor. bassiana和Claviceps purpurea的mat1-1-1基因中α-结构域相应核苷酸序列同源性分别为61%、63%和68%;根据mat1-1-1和mat1-2-1部分基因序列设计特异性引物,并使用PCR方法检测了来源于3个异源子座的240个子囊孢子单孢菌株和50个田间菌株的交配型基因,结果显示稻曲菌mat1-1-1和mat1-2-1基因分别存在于不同菌株中;将具有相同或不同交配型基因的菌株配对接种,发现菌核通常产生在mat1-1-1和mat1-2-1基因型菌株配对接种产生的稻曲球上,其中大部分菌核可萌发产生子座,而菌株单独接种或具有相同交配型基因的菌株配对接种水稻后多数不能形成菌核;根据以上结果初步推断稻曲菌为异宗配合真菌。