Breeding drought tolerant cowpea: constraints,accomplishments, and future prospects

This review presents an overview of accomplishments on different aspects of cowpea breeding for drought tolerance. Furthermore it provides options to enhance the genetic potential of the crop by minimizing yield loss due to drought stress. Recent efforts have focused on the genetic dissection of drought tolerance through identification of markers defining quantitative trait loci (QTL) with effects on specific traits related to drought tolerance. Others have studied the relationship of the drought response and yield components, morphological traits and physiological parameters. To our knowledge, QTLs with effects on drought tolerance have not yet been identified in cowpea. The main reason is that very few researchers are working on drought tolerance in cowpea. Some other reasons might be related to the complex nature of the drought stress response, and partly to the difficulties associated with reliable and reproducible measurements of a single trait linked to specific molecular markers to be used for marker assisted breeding. Despite the fact that extensive research has been conducted on the screening aspects for drought tolerance in cowpea only very few—like the ‘wooden box’ technique—have been successfully used to select parental genotypes exhibiting different mechanisms of drought tolerance. Field and pot testing of these genotypes demonstrated a close correspondence between drought tolerance at seedling and reproductive stages. Some researchers selected a variety of candidate genes and used differential screening methods to identify cDNAs from genes that may underlie different drought tolerance pathways in cowpea. Reverse genetic analysis still needs to be done to confirm the functions of these genes in cowpea. Understanding the genetics of drought tolerance and identification of DNA markers linked to QTLs, with a clear path towards localizing chromosomal regions or candidate genes involved in drought tolerance will help cowpea breeders to develop improved varieties that combine drought tolerance with other desired traits using marker assisted selection.

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Genetics,genomics and breeding of groundnut (Arachis hypogaea L.)

Groundnut is an important food and oil crop in the semiarid tropics, contributing to household food consumption and cash income. In Asia and Africa, yields are low attributed to various production constraints. This review paper highlights advances in genetics, genomics and breeding to improve the productivity of groundnut. Genetic studies concerning inheritance, genetic variability and heritability, combining ability and trait correlations have provided a better understanding of the crop's genetics to develop appropriate breeding strategies for target traits. Several improved lines and sources of variability have been identified or developed for various economically important traits through conventional breeding. Significant advances have also been made in groundnut genomics including genome sequencing, marker development and genetic and trait mapping. These advances have led to a better understanding of the groundnut genome, discovery of genes/variants for traits of interest and integration of marker‐assisted breeding for selected traits. The integration of genomic tools into the breeding process accompanied with increased precision of yield trialing and phenotyping will increase the efficiency and enhance the genetic gain for release of improved groundnut varieties.     

A decade of Tropical Legumes projects: Development and adoption of improved varieties,creation of market‐demand to benefit smallholder farmers and empowerment of national programmes in sub‐Saharan Africa and South Asia

This article highlights 12 years (2007–2019) of research, achievements, lessons learned, challenges and gaps in discovery‐to‐delivery research in legumes emanating from three projects, collectively called Tropical Legumes (TL) with a total investment of about US$ 67 million funded by the Bill & Melinda Gates Foundation. These projects were implemented by three CGIAR centres (ICRISAT, CIAT and IITA) together with 15 national agricultural research system partners in sub‐Saharan Africa and South Asia. The TL projects together with some of their precursors and complementary projects from other agencies, facilitated the development of 266 improved legume varieties and the production of about 497,901 tons of certified seeds of the target legume crops in the focus countries. The certified seeds have been planted on about 5.0 million ha by more than 25 million smallholder farmers in the 15 countries and beyond, producing about 6.1 million tons of grain worth US$ 3.2 billion. Furthermore, the projects also trained 52 next generation scientists that included 10 women, by supporting 34 Masters degrees and 18 PhD degrees.     

Genetic diversity of Pseudomonas syringae pv. actinidiae,pathogen of kiwifruit bacterial canker

Bacterial canker disease of kiwifruit currently occurs in at least 15 countries, causing serious damage. The causative agent of the disease is Pseudomonas syringae pv. actinidiae (Psa), which is genetically diverse and is currently classified into five biovars, namely, biovars 1, 2, 3, 5 and 6. In Japan, four biovars except biovar 2 have been found so far. These biovars have been confirmed to have differences in the virulence and composition of pathogenicity-related genes, such as toxin biosynthesis and type III effector genes. Biovars 1 and 6 possess the tox island, a genomic island of approximately 38 kb, which contains phaseolotoxin biosynthesis genes (argK-tox cluster) and is confirmed to have been acquired from other bacteria through horizontal transfers. Also, on the megaplasmid possessed by biovar 6, there exist coronatine biosynthesis genes, and biovar 6 has the ability to produce two phytotoxins, phaseolotoxin and coronatine. In 2014, biovar 3, considered to be of foreign origin, was confirmed for the first time in Japan. Biovar 5, whose virulence is relatively weak, is distributed only in a limited area. In addition to the tox island and various plasmids, a large number of mobile genetic elements are confirmed to be present on the Psa genomes, which might have played a major role in helping Psa to acquire new features. In order to understand how Psa acquired the ability to infect kiwifruit systemically, it is important to make polyphasic comparisons with related pathovars, such as P. syringae pv. theae and pv. actinidifoliorum.     

非生物胁迫条件小麦根系性状的遗传学基础研究进展

作物根系与水肥利用密切相关,发掘根系性状相关遗传位点或候选基因,对于培育适宜特定土壤环境的小麦新品种具有重要意义。为系统了解低氮磷供应、盐碱、干旱等非生物胁迫对根系的影响,以及小麦根系性状遗传定位进展,本研究对近几十年相关文献进行了调研。发现尽管目前对小麦根系性状遗传解析工作已有较多报道,但许多根系性状QTL区间在不同研究间难以吻合,限制了分子标记开发和候选基因的发掘。随着高密度SNP芯片的开发及全基因组重测序技术的发展,今后整合"表型组"、"基因组"、"转录组"和"代谢组"对特定环境条件下小麦根系性状进行解析,可快速、高效地发掘特定环境条件下的优异等位变异和候选基因。本研究对于了解非生物胁迫条件小麦根系性状的遗传学基础具有参考价值。     

林木基因组学研究概述

林木作为重要的自然资源,在生态、社会和经济建设中起着重要的作用,基因作图、基因测序、基因表达的系统分析以及DNA芯片等生物技术的应用为林木遗传机制的研究提供有利的工具,从而为林木新品种的培育提供更为有效的途径。笔者重点对林木结构基因组学、功能基因组学和蛋白质组学的主要研究内容、研究方法和研究进展三个方面进行综述,并对与林木基因组学研究密切相关的生物信息学进行阐述,最后对林木基因组学的发展进行简单展望。     

微生物区系的功能基因组研究方法学

微生物在生态环境中具有重要作用,与整个生态系统中物质循环和能量流动密切相关。目前微生物区系的研究不断揭示环境样品中微生物群体的结构和功能。系统生物学研究思路不断地被引入进来,例如微生物区系基因组学、宏蛋白组学、生物信息学等。后基因组研究将对微生物区系的发展起到极其重要的作用。文章对应用到微生物区系研究的一些生物学方法进行了综述。     

禾谷镰刀菌基因组学研究进展

禾谷镰刀菌是小麦和大麦生产上一类重大的病原真菌。禾谷镰刀菌全基因组测序的完成,为禾谷镰刀菌功能基因的发掘提供了十分有利的信息。简述了禾谷镰刀菌在基因组学,包括比较基因组学和功能基因组学等领域的研究进展。     

微孢子虫O-甘露糖糖基化通路相关酶基因序列的比较分析

糖蛋白在免疫识别、信号转导等生命进程中扮演重要角色。为研究微孢子虫糖蛋白及其糖基化类型,采用比较基因组学方法对微孢子虫O-甘露糖糖基化通路进行分析。真核生物的O-甘露糖糖基化通路中有6种主要酶类,包括己糖激酶、磷酸甘露糖酶、GDP甘露糖磷酸化酶、Dol-P甘露糖合成酶、甘露糖转移酶、Dol-P甘露糖蛋白甘露糖转移酶。通过生物信息学方法分析家蚕微孢子虫(Nosema bombycis)、蜜蜂微孢子虫(Nosema ceranae)、兔脑炎微孢子虫(Encephalitozoon cuniculi)、肠脑炎微孢子虫(Encephalitozoon intestinalis)、比氏肠道微孢子虫(Encephalitozoon bieneusi)和柞蚕微孢子虫(Nosema antheraea)的这6种酶基因编码氨基酸序列特征及结构域类型,发现这些酶的垂直同源基因比较保守,多重序列比对表明在6种微孢子虫之间,6种酶的氨基酸序列相似性比较高,系统进化分析显示同属的微孢子虫多聚为一簇。研究结果表明,N.bombycis、N.ceranae、E.cuniculi、E.intestinalis和N.antheraea 5种微孢子虫的O-甘露糖糖基化的蛋白质修饰通路是完整、保守的,然而在E.bieneusi中,其关键酶Dol-P甘露糖蛋白甘露糖转移酶的氨基酸序列比较短,只有342个氨基酸,缺失了关键结构域PMT,因此可能无法完成O-甘露糖糖基化修饰。以上微孢子虫的O-甘露糖糖基化通路中6种主要酶的序列信息,为后续解析家蚕微孢子虫糖基化通路及对糖蛋白糖基化类型与功能的研究提供了线索。     

柞蚕功能基因研究进展

柞蚕是起源于中国的大型绢丝昆虫,保护和开发其基因资源对柞蚕业的可持续发展具有重要意义。根据GenBank数据库的检索结果,从能量相关蛋白基因、免疫相关基因、神经肽类基因、昼夜节律相关基因、气味结合蛋白基因、表皮蛋白基因、代谢相关酶类基因等方面介绍柞蚕功能基因分离研究进展,并提出了今后开展有关研究的对策和建议。