Project description:Jiashi melon and 86-1 melon were inoculated with Alternaria alternata, and the difference of gene expression was analyzed after 0, 6, 12, 18 and 24 days storage.
Project description:Cotton premature leaf senescence often occurred with an increasing frequency in many cotton growing areas and caused serious reduction in yield and quality of cotton has been one of the impontant factors that restrict severely the production of cotton.Our laboratory studies showed chilling stress is the key factor that induced A. alternatia infection, caused Alternaria disease and then lead to cotton leaf senescence, but the molecular mechanism of cotton premature leaf senscence is still unclear. We used microarrays to study molecular mechanism of chilling stress causing Alternaria alternata infection and leading to cotton leaf senescence and find the key genes during this process.
Project description:Cotton premature leaf senescence often occurred with an increasing frequency in many cotton growing areas and caused serious reduction in yield and quality of cotton has been one of the impontant factors that restrict severely the production of cotton.Our laboratory studies showed chilling stress is the key factor that induced A. alternatia infection, caused Alternaria disease and then lead to cotton leaf senescence, but the molecular mechanism of cotton premature leaf senscence is still unclear. We used microarrays to study molecular mechanism of chilling stress causing Alternaria alternata infection and leading to cotton leaf senescence and find the key genes during this process. Plants were grown in growth chamber with a 14/10 hours photoperiod, 28â/22â. Three-to-four leaves stage cotton plants were pre-treated by chilling stress with the low temperatures of 16/12â day/night for a fixed time length of 3 days. While, the normal growth plants were sustained growing at optimal temperature of 28/20â day/night. And then, both chilling stress pre-treated and normal growth cotton plants were inoculated with Alternaria. alternata isolate A1. The mock inoculations were performed with sterilized water. Cotton leaf Samples were respectively collected at 3, 6 days after inoculation (DAI) for RNA extraction and hybridization on Affymetrix microarrays. To that end, we collected 8 samples, i.e. chilling stress pre-treated cotton leaves: 3 DAI (C) and its mock control (D), 6 DAI (E) and its mock control (F); normal growth cotton leaves: 3 DAI (H) and its mock control (I), 6 DAI (J) and its mock control (K). All samples were arranged in completely randomized designed with three replications for each treatment.
Project description:Apple leaf spot caused by the Alternaria alternata f. sp. mali (ALT1) fungus is one of the most devastating diseases of apple (Malus × domestica). We identified a hairpin RNA (hpRNA)-mediated small RNAs, MdhpRNA277, from apple (cv. ‘Golden Delicious’) that is induced by infection with ALT1. MdhpRNA277 produces mdm-siR277-1 and mdm-siR277-2, which target five R genes, MdRNL1, MdRNL2, MdRNL3, MdRNL4, and MdRNL5, that are expressed at high levels in the resistant apple variety ‘Hanfu’ and at low levels in the susceptible variety ‘Golden Delicious’ following ALT1 infection. MdhpRNA277 is strongly induced in ‘Golden Delicious’ but was not induced in ‘Hanfu’ following ALT1 inoculation. The promoter activity of MdhpRNA277 was much stronger in ‘Golden Delicious’ than in ‘Hanfu’ after ALT1 inoculation. We identified a single nucleotide polymorphism (SNP) in the MdhpRNA277 promoter region between the susceptible variety ‘Golden Delicious’ (pMdhpRNA277-GD) and resistant variety ‘Hanfu’ (pMdhpRNA277-HF). The transcription factor MdWHy binds to pMdhpRNA277-GD, but not to pMdhpRNA277-HF. Transgenic ‘GL-3’ apple lines expressing pMdhpRNA277-GD: MdhpRNA277 were more susceptible to ALT1 infection than were those expressing pMdhpRNA277-HF:MdhpRNA277 due to induced mdm-siR277 accumulation and low levels of expression of the five target R genes. The failure of MdWHy to bind to pMdhpRNA277-HF might contribute to the low levels of MdhpRNA277 and mdm-siR277-1/-2 expression and the high levels of R gene expression and resistance to Alternaria leaf spot in resistant apple varieties. We confirmed that the SNP in pMdhpRNA277 is associated with Alternaria leaf spot resistance by analyzing the progeny of three additional crosses. The SNP identified in this study could be used as a marker to distinguish between apple varieties that are resistant or susceptible to Alternaria leaf spot.
