Chickpea

The narrow genetic base of cultivated chickpea warrants systematic collection, documentation and evaluation of chickpea germplasm and particularly wild Cicer species for effective and efficient use in chickpea breeding programmes. Limiting factors to crop production, possible solutions and ways to overcome them, importance of wild relatives and barriers to alien gene introgression and strategies to overcome them and traits for base broadening have been discussed. It has been clearly demonstrated that resistance to major biotic and abiotic stresses can be successfully introgressed from the primary gene pool comprising progenitor species. However, many desirable traits including high degree of resistance to multiple stresses that are present in the species belonging to secondary and tertiary gene pools can also be introgressed by using special techniques to overcome pre- and post-fertilization barriers. Besides resistance to various biotic and abiotic stresses, the yield QTLs have also been introgressed from wild Cicer species to cultivated varieties. Status and importance of molecular markers, genome mapping and genomic tools for chickpea improvement are elaborated. Because of major genes for various biotic and abiotic stresses, the transfer of agronomically important traits into elite cultivars has been made easy and practical through marker-assisted selection and marker-assisted backcross. The usefulness of molecular markers such as SSR and SNP for the construction of high-density genetic maps of chickpea and for the identification of genes/QTLs for stress resistance, quality and yield contributing traits has also been discussed

Characterization of a pepper vein banding virus from chili pepper in India

A survey conducted in pepper-growing tracts of Karnataka State, covering 165 fields in 33 villages, revealed the occurrence of many pepper mosaic diseases. Based on reactions on selected test plants, the viruses were identified as pepper vein banding virus (PVBV), pepper veinal mottle virus, potato virus Y, cucumber mosaic virus, and tobacco mosaic virus. Among these, PVBV was the most prevalent. PVBV was purified from infected leaves of Capsicum annuum cv. California Wonder. Electron microscopy revealed flexuous rod-shaped particles in the purified preparations. The coat protein (CP) molecular weight was 35,000, which is similar to members of the Potyvirus group. As in other potyviruses, the CP underwent proteolytic degradation to a fragment with a molecular weight of 31,000. Both of these bands cross-reacted with antibodies against tobacco etch virus in Western blots. Polyclonal antibodies were produced against PVBV. Cross-reactivity studies with other potyviral antisera showed that PVBV is serologically closer to peanut mottle virus than to peanut stripe Virus or sorghum potyvirus. N-terminal sequence analysis of the intact CP and trypsin-resistant core revealed that PVBV is a distinct member of the Potyvirus group

Epidemiology of Tospoviruses in South and Southeast Asia: Current status and future prospects

Tospoviruses are emerging as a major constraint to the production of a broad range of economically important crops in South and Southeast Asia (S & SEA). Available data suggest that the majority of these viruses belong to serogroup IV (Watermelon silver mottle virus serogroup). Many of these viruses show geographical structuring in that they are restricted to the Asian continent. In recent years, tospovirus species like Capsicum chlorosis virus and Iris yellow spot virus, present in other continents, have been reported in the S & SEA region. Among different species of thrips (Thysanoptera: Thripidae) that have been confirmed as vectors of one or more tospoviruses worldwide, only a few have been authenticated to be present in the S & SEA region. The current knowledge on the distribution of thrips vectors and tospoviruses in the region will be reviewed and the research needs for a better understanding of the growing impact of tospoviruses and thrips vectors will be discussed

Radiant frost tolerance in pulse crops-a review

Radiant frost is a major abiotic stress, and one of the principal limiting factors for agricultural production worldwide, including Australia. Legumes, including field pea, faba bean, lentil and chickpea, are very sensitive to chilling and freezing temperatures, particularly at the flowering, early pod formation and seed filling stages. Radiant frost events occur when plants and soil absorb the sunlight during the day time and radiate heat during the night when the sky is clear and the air is still. Dense chilled air settles into the lowest areas of the canopy, where the most serious frost damage occurs. The cold air causes nucleation of the intracellular fluid in plant tissues and the subsequent rupturing of the plasma membrane. Among the cool season grain legume crops, chickpea, lentil and faba bean and field pea are the most susceptible to radiant frost injury during the reproductive stages. The more sensitive stages are flowering and podding. Frost at the reproductive stage results in flower abortion, poor pod set and impaired pod filling, leading to a drastic reduction in yield and quality. In contrast, in the UK and European countries, frost stress is related to the vegetative stages and, in particular, the effects of frost have been studied on cotyledon, uni/tri-foliolate leaf and seedling stages during the first few weeks of growth. Few winter genotypes have been identified as frost tolerant at vegetative stages. Vegetative frost tolerance is not related to reproductive frost tolerance, and hybrids from the vegetative frost-tolerant genotypes may not necessarily be tolerant at the reproductive stage. Tolerance to radiant frost has an inverse relationship with plant age. In the field, frost tolerance decreases from the vegetative stage to reproductive stage. Unlike wheat and barley, it is difficult to analyse and score frost damage in grain legume crops due to the presence of various phenophases on one plant at the reproductive stage. The extent of frost damage depends on the specific phenophases on a particular plant. However, current studies on genetic transformation of cold tolerant gene(s), membrane modifications, anti-freeze substances and ice nucleating or inhibiting agents provide useful information to improve our current understanding on frost damage and related mechanisms. The effects of frost damage on yield and grain quality illustrate the significance of this area of research. This review discusses the problem of radiant frost damage to cool season legumes in Australia and the associated research that has been carried out to combat this problem locally and worldwide. The available literature varies between species, specific climatic conditions and origin.Ahmad Maqbool, Shaista Shafiq and Lachlan Lak

Chickpea Genomics

As precise phenotyping is essential and the cost of generating phenotyping data at every generation is very expensive, recent advances in genomics technologies and the availability of a wide range of genotyping platforms have made the cost of genotyping much less expensive compared with phenotyping. The recent developments in sequencing technologies have manifold increased the repertoire of various types of markers that are available in chickpea including SSRs, SNPs, DArTs, hundreds of thousands transcript reads and BAC-end sequences saturated genetic maps, QTL maps as well as physical maps, and the sequencing of both kabuli and desi type has greatly helped in using marker-assisted technologies to be applied in plant breeding. Germplasm resequencing for identification of genome-wide SNPs and their subsequent utilization in genomic selection has the potential to break the yield barrier being experienced in chickpea and many other crops. Genomic-assisted breeding for marker-assisted backcrossing (MABC) for introgressing QTL region, marker-assisted recurrent selection, gene pyramiding, marker-assisted selection (MAS), and genomic selection can now be taken up in chickpea. The conventional plant breeding should take these tools to make greater genetic gains, increase selection potential, and have faster breeding cycles so that the genetic improvement gains are increased in chickpea

Chickpea Genomics

As precise phenotyping is essential and the cost of generating phenotyping data at every generation is very expensive, recent advances in genomics technologies and the availability of a wide range of genotyping platforms have made the cost of genotyping much less expensive compared with phenotyping. The recent developments in sequencing technologies have manifold increased the repertoire of various types of markers that are available in chickpea including SSRs, SNPs, DArTs, hundreds of thousands transcript reads and BAC-end sequences saturated genetic maps, QTL maps as well as physical maps, and the sequencing of both kabuli and desi type has greatly helped in using marker-assisted technologies to be applied in plant breeding. Germplasm resequencing for identification of genome-wide SNPs and their subsequent utilization in genomic selection has the potential to break the yield barrier being experienced in chickpea and many other crops. Genomic-assisted breeding for marker-assisted backcrossing (MABC) for introgressing QTL region, marker-assisted recurrent selection, gene pyramiding, marker-assisted selection (MAS), and genomic selection can now be taken up in chickpea. The conventional plant breeding should take these tools to make greater genetic gains, increase selection potential, and have faster breeding cycles so that the genetic improvement gains are increased in chickpea