Genetic variability for resistance to sorghum downy mildew (Peronosclerospora sorghi) and Rajasthan downy mildew (P. heteropogoni) in the tropical/sub-tropical Asian maize germplasm

Downy mildews cause considerable damage to maize (Zea mays L.) worldwide, particularly in the tropical Asia. We have evaluated a set of 42 tropical/sub-tropical maize inbred lines developed in different countries in Asia (India, Thailand and Philippines), and Mexico, for analysing the genetic variability for resistance to sorghum downy mildew [Peronosclerospora sorghi; SDM] and Rajasthan downy mildew [P. heteropogoni; RDM]. Experiments were carried out in replicated trials under artificial infection in field conditions against SDM and RDM at Mandya in Karnataka, India, and Udaipur in Rajasthan, India, respectively, during 1999 and 2000. The study resulted in identification of five inbred lines offering consistent and strong resistance to both SDM and RDM, while several inbred lines revealed resistance only to RDM. It was also revealed that the SDM-resistant inbreds are invariably resistant to RDM, while the RDM-resistant inbreds might show differential responses to the SDM. The maize inbred lines identified in this study with broad-spectrum resistance to downy mildews could be potentially useful for basic and applied research work on downy mildews in tropical Asia. This revised version was published online in August 2006 with corrections to the Cover Date.     

中期喷施多效唑对甜高粱生长及生理特性的影响

为了研究中期喷施多效唑对甜高粱生长发育与生理特性的影响,本文采用不同浓度的多效唑在伸长期初期对甜高粱进行叶面喷施处理。结果表明,适宜浓度的多效唑处理可以有效的提高甜高粱叶片的可溶性糖、叶绿素、可溶性蛋白质等的含量,显著的增强了甜高粱叶片的蔗糖合成酶活性,对气孔导度、蒸腾速率和净光合速率有明显的增强效应,有效的降低了甜高粱的株高和茎长,而对茎杆的增粗有促进作用,从而提高了甜高粱的抗倒伏能力,最终使茎杆产量提高。多效唑比较适宜的使用浓度为0.75g/L。     

脐橙新品种‘龙回红’果实发育后期外观品质及内在营养成分的动态变化

‘龙回红’脐橙由‘纽荷尔’脐橙芽变而来,2012年经江西省农作物品种审定委员会认定的脐橙新品种,其变异株系适应性强,多数生物学性状均优于其母本‘纽荷尔’脐橙。为更全面了解该脐橙品种在果实发育成熟阶段的外观品质及内在营养成分的动态变化情况,本研究以‘龙回红’脐橙及其母本‘纽荷尔’脐橙为试材,对以上两个脐橙品种果实发育后期的相关生理生化指标进行测定,结果表明:随着果实的发育成熟,‘龙回红’和‘纽荷尔’的外观品质(单果重及横,纵径,果皮色差指数)呈逐渐上升的变化趋势;可溶性固形物(total soluble solid, TSS)、总糖、维生素C (vitamin C, Vc)含量呈先上升后下降的趋势,可滴定酸(titratable acid,TA)含量呈逐渐下降的变化趋势。‘龙回红’脐橙果实的红绿色差a*、色差指数(citrus colour index, CCI)、TSS、总糖含量、单果重及横、纵径均高于‘纽荷尔’脐橙,TA和Vc含量低于‘纽荷尔’,其外观品质和果实风味优于‘纽荷尔’脐橙。     

一个控制水稻叶色白化转绿及多分蘖矮杆性状基因hw-1(t)的鉴定

通过空间诱变从光身稻品种Francis的M₂群体中发现一株叶色白化转绿、多分蘖矮秆突变体hfa-1。hfa-1在三叶期之前完全白化,随后转绿。白化转绿表型受生长发育和温度调控。亚细胞结构观察发现hfa-1叶绿体发育异常抑制叶绿素合成,造成光合效率降低,产生白化表型。hfa-1的多分蘖表型是由于高节位分蘖芽激活所致,初步鉴定与苗期叶片IAA (吲哚乙酸)含量无关。hfa-1的矮生性则由节间长度缩短所致,与苗期GA (赤霉素)的合成和信号传导无关。遗传分析表明hfa-1的白化转绿、多分蘖矮秆表型受单隐性核基因hw-1(t)控制。利用hfa-1与粳稻品种02428杂交获得的F₂群体将hw-1(t)定位在水稻第4染色体长臂上两个InDel标记HW27和HW7间46.9 kb的物理距离内,该区域有13个阅读框架,其中LOC_Os04g57320编码IMMUTANTS蛋白,推测为hw-1(t)的候选基因。     

Influence of single-nucleotide polymorphisms in the gene encoding granule-bound starch synthase I on amylose content in Vietnamese rice cultivars

Amylose content is one of the most important factors influencing the physical and chemical properties of starch in rice. Analysis of 352 Vietnamese rice cultivars revealed a wide range of variation in apparent amylose content and the expression level of granule-bound starch synthase. On the basis of single-nucleotide polymorphisms (SNP) at the splicing donor site of the first intron and in the coding region of the granule-bound starch synthase I gene, Waxy gene, alleles can be classified into seven groups that reflect differences in apparent amylose content. The very low and low apparent amylose content levels were tightly associated with a G to T in the first intron whereas intermediate and high amylose was associated with a T genotype at SNP in exon 10. The correlation between the combination of T genotype at SNP in the first intron, C in exon 6, or C in exon 10 was predominant among low amylose rice varieties. Our analysis confirmed the existence of Wx^op allele in Vietnamese rice germplasm. The results of this study suggest that the low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site.     

青冈栎林分空间结构对林下更新的影响

林分空间结构会显著影响其林下幼树更新.为明确其影响林下幼树更新的关键因子,以湖南省青羊湖国有林场青冈栎林天然次生林为研究对象,测量幼树株数密度、树高、地径和冠幅,计算混交度、大小比数、开敞度指数以及聚集指数代表林分空间结构,评价林下幼树更新情况,并用灰色关联度分析方法探究两者间的相关关系.结果 表明,青羊湖国有林场13...     

水稻叶色白化转绿及多分蘖矮秆基因hw-1(t)的图位克隆

通过增加作图群体的样本量, 将控制水稻白化转绿和多分蘖矮秆的基因hw-1(t)定位在第4染色体长臂2个InDel标记HW36和HW7之间24.9 kb的物理距离内, 该区域含有5个阅读框架。测序及酶切分析表明, 突变体hfa-1仅在LOC_Os04g57320产生一个碱基(G→A)的突变, 导致翻译提取终止, 推断LOC_Os04g57320为hw-1(t)。进一步分析发现hw-1(t)在水稻基因组中为单拷贝, 与拟南芥im和番茄PTOX基因同源性较高, 但在转录子和蛋白质结构上存在一定差异;基因表达分析显示HW-1(t)属组成型表达基因, 表达不受光照影响。     

不同种植模式下根系分泌物对玉米生长及产量的影响

为探究大豆和甘薯的根系分泌物对玉米生长及产量的影响,通过盆栽根系分泌物吸附试验,研究了不同活性炭处理方式对玉米/大豆(B1)、玉米/甘薯(B2)及玉米净作(B3)3种种植模式下玉米光合特性、荧光参数及生物产量的变化规律。结果表明:加活性炭处理(A1)较未加活性炭处理(A2)抑制了玉米生长,但玉米产量差异不显著。加活性炭时,由于根系分泌物被吸附,玉米的光合速率、荧光参数和产量在各种植模式之间差异不显著;未加活性炭时,大豆的根系分泌物促进玉米生长和提高玉米产量,甘薯的根系分泌物抑制玉米生长和降低玉米产量,B1处理下玉米的根干重、根系活力、净光合速率和子粒干重比B3处理分别高15.81%、53.20%、19.94%和60.84%,而B2处理则比B3处理分别低19.92%、4.33%、16.96%和24.32%。     

猕猴桃果肉颜色相关色素代谢研究进展

猕猴桃含有独特的风味和丰富的营养价值,深受消费者的亲睐。猕猴桃果肉颜色各异,系统叙述了猕猴桃果肉颜色的种类、果肉颜色在发育过程中的变化、显微结构的变化、色素类物质的种类和变化、以及叶绿素、类胡萝卜素、和花色素苷代谢途径及其分子调控机理。提出了猕猴桃果肉颜色研究现阶段存在的问题,并对其研究前景进行了展望。     

盐胁迫对松果菊生长及其菊苣酸含量的影响

为了探讨盐胁迫对松果菊生长及其药用成分菊苣酸含量的影响,分别以0、30、60、90、120和150 mmol?L-1的NaCl处理土培的松果菊植株,并测定处理后的松果菊盐害指数、鲜重、干重以及菊苣酸含量。结果表明：盐害指数随着盐浓度的升高而升高;120 mmol?L-1及以下浓度的NaCl处理对松果菊鲜重影响并不明显,而150 mmol?L-1时则使鲜重显著降低;随着盐浓度的升高,松果菊干重呈逐渐减小的趋势;菊苣酸含量随盐浓度的升高呈先升高再下降的趋势,在90 mmol?L-1时达到最大值;菊苣酸的单株产量在盐浓度为0~60 mmol?L-1时无显著变化,在90 mmol?L-1时显著升高,之后显著降低。盐胁迫虽然对松果菊生长产生了一定的盐害作用,但在一定的盐浓度范围内（0~90 mmol?L-1）也同时提高了菊苣酸的含量水平。