EVALUATING TRANSCRIPTOME CHANGES IN SWEET POTATO DURING VIRAL PATHOGEN INFECTION

117 pagesSweet potato (Ipomoea batatas) ranks among the most important crops in the world and provides nutritional and economic sustainability for subsistence farmers in Sub-Saharan Africa. Its production is mainly constrained by Sweet potato virus disease (SPVD) caused by the coinfection by two positive-sense single-stranded RNA viruses, Sweet potato chlorotic stunt virus and Sweet potato feathery mottle virus. Current understanding of sweet potato responses to these viruses at the molecular level remains very limited. In this study, we performed deep transcriptome sequencing in three sweet potato cultivars with varying degrees of viral resistance, coupled with comprehensive and integrated analytical approaches, to identify biological pathways that contribute to both general and specific host responses to these important viral pathogens. We found that much of the antiviral response was effector-triggered immunity (ETI) specific, and that the expression patterns (both timing and magnitude) of this response were dependent on each cultivar’s resistance to SPVD

Differential gene regulatory pathways and co-expression networks associated with fire blight infection in apple (Malus × domestica)

Disease resistance: How apples fight blight Different apple varieties, such as ‘Gala’ and ‘Empire,’ defend themselves against fire blight in different ways, and studying how they do it may help in breeding varieties with better resistance. Fire blight is a devastating bacterial disease that can destroy entire orchard blocks in a single season. Breeding for increased resistance is one of the most efficient ways to combat it. Some apple varieties are naturally more resistant than others, but the underlying genetics are not well understood. Awais Khan at Cornell University in New York and co-workers investigated how the ‘Gala’ and ‘Empire’ varieties defend themselves in the first 72 h after infection. ‘Empire’ showed stronger resistance than ‘Gala,’ with many distinct resistance mechanisms. The researchers identified several resistance genes in each variety, which may eventually be used in breeding more blight-resistant apple varieties

A florigen paralog is required for short-day vernalization in a pooid grass

Perception of seasonal cues is critical for reproductive success in many plants. Exposure to winter cold is a cue that can confer competence to flower in the spring via a process known as vernalization. In certain grasses, exposure to short days is another winter cue that can lead to a vernalized state. In Brachypodium distachyon, we find that natural variation for the ability of short days to confer competence to flower is due to allelic variation of the FLOWERING LOCUS T (FT1) paralog FT-like9 (FTL9). An active FTL9 allele is required for the acquisition of floral competence, demonstrating a novel role for a member of the FT family of genes. Loss of the short- day vernalization response appears to have arisen once in B. distachyon and spread through diverse lineages indicating that this loss has adaptive value, perhaps by delaying spring flowering until the danger of cold damage to flowers has subsided

Genetic Architecture of Flowering-Time Variation in Brachypodium distachyon.

The transition to reproductive development is a crucial step in the plant life cycle, and the timing of this transition is an important factor in crop yields. Here, we report new insights into the genetic control of natural variation in flowering time in Brachypodium distachyon, a nondomesticated pooid grass closely related to cereals such as wheat (Triticum spp.) and barley (Hordeum vulgare L.). A recombinant inbred line population derived from a cross between the rapid-flowering accession Bd21 and the delayed-flowering accession Bd1-1 were grown in a variety of environmental conditions to enable exploration of the genetic architecture of flowering time. A genotyping-by-sequencing approach was used to develop SNP markers for genetic map construction, and quantitative trait loci (QTLs) that control differences in flowering time were identified. Many of the flowering-time QTLs are detected across a range of photoperiod and vernalization conditions, suggesting that the genetic control of flowering within this population is robust. The two major QTLs identified in undomesticated B. distachyon colocalize with VERNALIZATION1/PHYTOCHROME C and VERNALIZATION2, loci identified as flowering regulators in the domesticated crops wheat and barley. This suggests that variation in flowering time is controlled in part by a set of genes broadly conserved within pooid grasses

Genetic Architecture of Flowering-Time Variation in Brachypodium distachyon.

The transition to reproductive development is a crucial step in the plant life cycle, and the timing of this transition is an important factor in crop yields. Here, we report new insights into the genetic control of natural variation in flowering time in Brachypodium distachyon, a nondomesticated pooid grass closely related to cereals such as wheat (Triticum spp.) and barley (Hordeum vulgare L.). A recombinant inbred line population derived from a cross between the rapid-flowering accession Bd21 and the delayed-flowering accession Bd1-1 were grown in a variety of environmental conditions to enable exploration of the genetic architecture of flowering time. A genotyping-by-sequencing approach was used to develop SNP markers for genetic map construction, and quantitative trait loci (QTLs) that control differences in flowering time were identified. Many of the flowering-time QTLs are detected across a range of photoperiod and vernalization conditions, suggesting that the genetic control of flowering within this population is robust. The two major QTLs identified in undomesticated B. distachyon colocalize with VERNALIZATION1/PHYTOCHROME C and VERNALIZATION2, loci identified as flowering regulators in the domesticated crops wheat and barley. This suggests that variation in flowering time is controlled in part by a set of genes broadly conserved within pooid grasses