稻瘿蚊为害(标葱)的空间分布型及其与有效穗关系的研究

稻瘿蚊为害的空间分布型属聚集分布,田间估计稻瘿蚊为害的最佳取样方法为棋盘法和平行线法,当每丛受害超过1苗时,抽样数量可稳定在151丛以下。标葱率和有效穗相关性测定表明：当标葱率在20％以下时,为害程度与有效穗的多少无显著相关;当标葱率大于20％时,标葱率与有效穗呈显著负相关,每受害加重5％,有效穗将减少0．37个／丛。     

Cultivation characteristics of immobilized Aspergillus oryzae for kojic acid production

Aspergillus oryzae in situ grown from spores entrapped in calcium alginate gel beads was used for the production of kojic acid. The immobilized cells in flask cultures produced kojic acid in a linear proportion while maintaining the stable metabolic activity for a prolonged production period. Kojic acid was accumulated up to a high concentration of 83 g/L, at which the kojic acid began to crystallize, and, thus, the culture had to be replaced with fresh media for the next batch culture. The overall productivities of two consecutive cultivations were higher than that of free mycelial fermentation. However, the production rate of kojic acid by the immobilized cells was suddenly decreased with the appearance of central cavernae inside the immobilized gel beads after 12 days of the third batch cultivation.     

SOBIR1 and AGB1 independently contribute to nonhost resistance to Pyricularia oryzae (syn. Magnaporthe oryzae) in Arabidopsis thaliana

ABSTRACT

Rice blast caused by Pyricularia oryzae (syn. Magnaporthe oryzae) is a disease devastating to rice. We have studied the Arabidopsis-P. oryzae pathosystem as a model system for nonhost resistance (NHR) and found that SOBIR1, but not BAK1, is a positive regulator of NHR to P. oryzae in Arabidopsis. AGB1 is also involved in NHR. However, the genetic interactions between SOBIR1, BAK1, and AGB1 are uncharacterized. In this study, we delineated the genetic interactions between SOBIR1, BAK1, and AGB1 in NHR to P. oryzae in Arabidopsis and found SOBIR1 and AGB1 independently control NHR to P. oryzae in Arabidopsis pen2-1 mutant plants. Furthermore, XLG2, but not TMM, has a positive role in penetration resistance to P. oryzae in Arabidopsis pen2-1 mutant plants. Our study characterized genetic interactions in Arabidopsis NHR.

Abbreviations: PRR: pattern recognition receptor, RLK: receptor-like kinase, RLP: receptor-like protein, BAK1: BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1, BIR1: BAK1-INTERACTING RECEPTOR-LIKE KINASE 1, SOBIR1: SUPPRESSOR OF BIR1-1-1, AGB1: ARABIDOPSIS G PROTEIN ß-SUBUNIT 1, XLG2: EXTRA-LARGE G PROTEIN 2     

温度对米象成虫飞行行为的影响

为探明温度对米象成虫的飞行行为的影响,应用起飞测定装置和昆虫飞行磨对不同温度条件下米象成虫的飞行参数进行了测定。结果显示23℃时,米象即可起飞;23～35℃内,60.0%～73.3%的米象个体具备飞行能力;温度对米象雌成虫的24 h累计飞行距离、24 h累计飞行时间和飞行速度均有显著影响,随温度的升高其飞行能力先增强后减弱,在32℃时上述3个飞行参数均有最大值。米象雄成虫的24 h累计飞行距离、24 h累计飞行时间和飞行速度受温度影响不显著,整体随测定温度的增加呈现先增大后减小的趋势,在29℃时有最大值。米象雌雄成虫的日常日行活动呈现一定的节律性,每日上午和傍晚以后有两个飞行活动高峰。研究结果明确了米象成虫在不同温度条件下的飞行行为特征,可为米象的扩散和害虫感染的预防提供数据支持。     

Analysis of the Relationship between Blast Resistance Genes and Disease Resistance of Rice Germplasm via Functional Molecular Markers

Rice blast disease is one of the most devastating diseases of rice (Oryza sativa L.) caused by the fungus Magnaporthe oryzae (M. oryzae), and neck blast is the most destructive phase of this illness. The underlying molecular mechanisms of rice blast resistance are not well known. Thus, we collected 150 rice varieties from different ecotypes in China and assessed the rice blast resistances under the natural conditions that favoured disease development in Jining, Shandong Province, China in 2017. Results showed that 92 (61.3%) and 58 (38.7%) rice varieties were resistant and susceptible to M. oryzae, respectively. Among the 150 rice varieties screened for the presence of 13 major blast resistance (R) genes against M. oryzae by using functional markers, 147 contained one to eight R genes. The relationship between R genes and disease response was discussed by analysing the phenotype and genotype of functional markers. The results showed that the rice blast resistance gene Pita was significantly correlated with rice blast resistance. Our results provided a basis for the further understanding of the distribution of 13 major R genes of rice blast in the germplasm resources of the tested rice varieties, and were meaningful for rice disease resistance breeding.     

Control of storage rot of cassava tuber caused by Rhizopus oryzae using some plant extracts

Abstract

The potency of Piper nigrum seed and leaf, Aframomum meleguata seed and Ageratum conyzoides leaf extracts in the control of cassava tuber rot caused by Rhizopus oryzae was investigated. Water, ethanol and petroleum ether were used as extracting solvents. These extracts were fungitoxic both in vitro and in vivo against the test pathogen. P. nigrum seed extracts were the best followed by those of A. meleguata seed, A. conyzoides leaf and then P. nigrum leaf. The extracts were more effective in controlling rot development in unwounded than wounded tubers especially when they were applied before inoculation with the test pathogen. Ethanol extracts gave the highest growth inhibition in vivo followed by water and the petroleum ether extract whereas water extracts showed marked superiority over the extracting solvents in checking rot development in cassava tuber. Water and ethanol extracts of P. nigrum seed and leaf, A. meleguata seed and A. conyzoides leaf could be used as pesticide of plant origin in the control of R. oryzae causing cassava tuber rot in storage.