Molecular breeding

About: Molecular breeding is a research topic. Over the lifetime, 2120 publications have been published within this topic receiving 56908 citations.

Back to the Wild: On a Quest for Donors Toward Salinity Tolerant Rice.

Abstract: Salinity stress affects global food producing areas by limiting both crop growth and yield. Attempts to develop salinity-tolerant rice varieties have had limited success due to the complexity of the salinity tolerance trait, high variation in the stress response and a lack of available donors for candidate genes for cultivated rice. As a result, finding suitable donors of genes and traits for salinity tolerance has become a major bottleneck in breeding for salinity tolerant crops. Twenty-two wild Oryza relatives have been recognized as important genetic resources for quantitatively inherited traits such as resistance and/or tolerance to abiotic and biotic stresses. In this review, we discuss the challenges and opportunities of such an approach by critically analyzing evolutionary, ecological, genetic, and physiological aspects of Oryza species. We argue that the strategy of rice breeding for better Na+ exclusion employed for the last few decades has reached a plateau and cannot deliver any further improvement in salinity tolerance in this species. This calls for a paradigm shift in rice breeding and more efforts toward targeting mechanisms of the tissue tolerance and a better utilization of the potential of wild rice where such traits are already present. We summarize the differences in salinity stress adaptation amongst cultivated and wild Oryza relatives and identify several key traits that should be targeted in future breeding programs. This includes: (1) efficient sequestration of Na+ in mesophyll cell vacuoles, with a strong emphasis on control of tonoplast leak channels; (2) more efficient control of xylem ion loading; (3) efficient cytosolic K+ retention in both root and leaf mesophyll cells; and (4) incorporating Na+ sequestration in trichrome. We conclude that while amongst all wild relatives, O. rufipogon is arguably a best source of germplasm at the moment, genes and traits from the wild relatives, O. coarctata, O. latifolia, and O. alta, should be targeted in future genetic programs to develop salt tolerant cultivated rice.

Control of Lignin Biosynthesis

Abstract: The ever increasing worldwide use of forest tree products, which coincides with the diminishing of natural forests, necessitates programs for efficient tree farming. For this purpose, there is a demand for accelerated tree improvement strategies that aim at developing trees as wood-producing crops with both improved trunk performance and specific exploitation characteristics. Objectives of primary importance to the forestry industry are the genetic control of traits such as growth, adaptation to environmental stress, disease resistance, wood uniformity, specific gravity and fiber quality. With classical breeding these demands will not be fulfilled within a reasonable time span because of the long generation time of trees. To meet these needs, forest trees are anticipated to become major targets for genetic engineering and molecular breeding in the coming years. Biotechnology now provides the necessary tools to solve many of the problems faced by conventional tree breeding programs, for example by the establishment of genetic maps of forest trees species such as poplar (Bradshaw et al., 1994) and the generation and potential use of DNA marker-assisted selection in breeding programs (e.g., Cervera et al., 1996). Furthermore, plant genetic transformation has now become a common technique for the introduction of novel traits into a wide range of tree species both for basic research and for applied purposes.

Breeding for Anthracnose Disease Resistance in Chili: Progress and Prospects

Abstract: Chili anthracnose is one of the most devastating fungal diseases affecting the quality and yield production of chili. The aim of this review is to summarize the current knowledge concerning the chili anthracnose disease, as well as to explore the use of marker-assisted breeding programs aimed at improving anthracnose disease resistance in this species. This disease is caused by the Colletotrichum species complex, and there have been ongoing screening methods of chili pepper genotypes with resistance to anthracnose in the field, as well as in laboratories. Conventional breeding involves phenotypic selection in the field, and it is more time-consuming compared to molecular breeding. The use of marker-assisted selection (MAS) on the basis of inheritance, the segregation ratio of resistance to susceptibility, and the gene-controlling resistance may contribute to the development of an improved chili variety and speed up the selection process, while also reducing genetic drag in the segregating population. More importantly, by using molecular markers, the linkage groups are determined dominantly and co-dominantly, meaning that the implementation of a reliable method to produce resistant varieties is crucial in future breeding programs. This updated information will offer a supportive direction for chili breeders to develop an anthracnose-resistant chili variety.