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Cheng C.-Z.,Southwest University | Cheng C.-Z.,Guangdong Academy of Agricultural Sciences | Cheng C.-Z.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | Yang J.-W.,Economic Crops Station | And 8 more authors.
Journal of Integrative Agriculture

The Citrus tristeza virus (CTV) uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strategies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA fragments from the three genes, and used them to construct vectors for expressing hairpin RNAs (hpRNAs). To facilitate the formation of hpRNAs, the constructs were introduced in a loop structure. Following transformation of sour orange (Citrus aurantium) with these constructs, 8 p20 hpRNA (hp20) and 1 p25 hpRNA (hp25) expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested following inoculation with CT14A and/or TR-L514, both of which are severe strains. Results showed that 3 lines (hp20-5, hp20-6 and hp20-8) were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently challenged with CT14A. These results showed that expressing p20 hpRNA was sufficient to confer sour orange with CTV resistance/tolerance. © 2015 Chinese Academy of Agricultural Sciences. Source

Wu Y.,Guangdong Academy of Agricultural Sciences | Wu Y.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | Yi G.,Guangdong Academy of Agricultural Sciences | Yi G.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | And 5 more authors.
Journal of Plant Physiology

Fusarium wilt of banana is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc). The fact that there are no economically viable biological, chemical, or cultural measures of controlling the disease in an infected field leads to search for alternative strategies involving activation of the plant's innate defense system. The mechanisms underlying systemic acquired resistance (SAR) are much less understood in monocots than in dicots. Since systemic protection of plants by attenuated or avirulent pathogens is a typical SAR response, the establishment of a biologically induced SAR model in banana is helpful to investigate the mechanism of SAR to Fusarium wilt. This paper described one such model using incompatible Foc race 1 to induce resistance against Foc tropical race 4 in an in vitro pathosystem. Consistent with the observation that the SAR provided the highest level of protection when the time interval between primary infection and challenge inoculation was 10d, the activities of defense-related enzymes such as phenylalanine ammonia lyase (PAL, EC, peroxidase (POD, EC, polyphenol oxidase (PPO, EC, and superoxide dismutase (SOD, EC in systemic tissues also reached the maximum level and were 2.00-2.43 times higher than that of the corresponding controls on the tenth day. The total salicylic acid (SA) content in roots of banana plantlets increased from about 1 to more than 5μgg-1 FW after the second leaf being inoculated with Foc race 1. The systemic up-regulation of MaNPR1A and MaNPR1B was followed by the second up-regulation of PR-1 and PR-3. Although SA and jasmonic acid (JA)/ethylene (ET) signaling are mostly antagonistic, systemic expression of PR genes regulated by different signaling pathways were simultaneously up-regulated after primary infection, indicating that both pathways are involved in the activation of the SAR. © 2013 Elsevier GmbH. Source

Liu C.H.,Guangdong Academy of Agricultural Sciences | Liu C.H.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | Liu Y.,Guangdong Academy of Agricultural Sciences | Liu Y.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | And 4 more authors.
Journal of Soil Science and Plant Nutrition

A field experiment was conducted to investigate the influence of composted pineapple residue return (CPRR) on soil bio-chemical properties and the growth performance of next-cropped pineapple plants. The results suggested that CPRR markedly decreased the soil bulk density and increased the contents of available P and K. CPRR significantly increased the abundance of bacteria and actinomycetes, and the activities of catalase, acid phosphatase and invertase in the soil were notably heightened. Growth characteristics, including the plant height, length of leaves and roots, leaf width, number of leaves and fresh weight of the aboveground and belowground parts were significantly increased by CPRR. The contents of chlorophyll, soluble sugars, and soluble protein, as well root vigor were also markedly increased. CPRR also increased the fruit transverse and longitudinal diameters, weight and yield of next-cropped pineapple. Source

Biswas M.K.,Guangdong Academy of Agricultural Sciences | Biswas M.K.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | Biswas M.K.,South China Agricultural University | Liu Y.,Huazhong Agricultural University | And 7 more authors.

The development of organized, informative, robust, user-friendly, and freely accessible molecular markers is imperative to the Musa marker assisted breeding program. Although several hundred SSR markers have already been developed, the number of informative, robust, and freely accessible Musa markers remains inadequate for some breeding applications. In view of this issue, we surveyed SSRs in four different data sets, developed largescale non-redundant highly informative therapeutic SSR markers, and classified them according to their attributes, as well as analyzed their cross-taxon transferability and utility for the genetic study of Musa and its relatives. A high SSR frequency (177 per Mbp) was found in the Musa genome. AT-rich dinucleotide repeats are predominant, and trinucleotide repeats are the most abundant in transcribed regions. A significant number of Musa SSRs are associated with pre-miRNAs, and 83% of these SSRs are promising candidates for the development of therapeutic SSR markers. Overall, 74% of the SSR markers were polymorphic, and 94% were transferable to at least one Musa spp. Two hundred forty-three markers generated a total of 1047 alleles, with 2-8 alleles each and an average of 4.38 alleles per locus. The PIC values ranged from 0.31 to 0.89 and averaged 0.71. We report the largest set of non-redundant, polymorphic, new SSR markers to be developed in Musa. These additional markers could be a valuable resource for marker-assisted breeding, genetic diversity and genomic studies of Musa and related species. © 2015 Biswas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Yang Q.-S.,Guangdong Academy of Agricultural Sciences | Yang Q.-S.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | Gao J.,Guangdong Academy of Agricultural Sciences | Gao J.,Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization | And 19 more authors.
BMC Genomics

Background: Banana and plantain (Musa spp.) comprise an important part of diets for millions of people around the globe. Low temperature is one of the key environmental stresses which greatly affects the global banana production. To understand the molecular mechanism of the cold-tolerance in plantain we used RNA-Seq based comparative transcriptomics analyses for both cold-sensitive banana and cold-tolerant plantain subjected to the cold stress for 0, 3 and 6 h. Results: The cold-response genes at early stage are identified and grouped in both species by GO analysis. The results show that 10 and 68 differentially expressed genes (DEGs) are identified for 3 and 6 h of cold stress respectively in plantain, while 40 and 238 DEGs are identified respectively in banana. GO classification analyses show that the majority of DEGs identified in both banana and plantain belong to 11 categories including regulation of transcription, response to stress signal transduction, etc. A similar profile for 28 DEGs was found in both banana and plantain for 6 h of cold stress, suggesting both share some common adaptation processes in response to cold stress. There are 17 DEGs found uniquely in cold-tolerance plantain, which were involved in signal transduction, abiotic stress, copper ion equilibrium, photosynthesis and photorespiration, sugar stimulation, protein modifications etc. Twelve early responsive genes including ICE1 and MYBS3 were selected and further assessed and confirmed by qPCR in the extended time course experiments (0, 3, 6, 24 and 48 h), which revealed significant expression difference of key genes in response to cold stress, especially ICE1 and MYBS3 between cold-sensitive banana and cold-tolerant plantain. Conclusions: We found that the cold-tolerance pathway appears selectively activated by regulation of ICE1 and MYBS3 expression in plantain under different stages of cold stress. We conclude that the rapid activation and selective induction of ICE1 and MYBS3 cold tolerance pathways in plantain, along with expression of other cold-specific genes, may be one of the main reasons that plantain has higher cold resistance than banana. © 2015 Yang et al. Source

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